WO2025133998A1

WO2025133998A1 - Respiratory support control using respiratory rate and heart rate

Info

Publication number: WO2025133998A1
Application number: PCT/IB2024/062937
Authority: WO
Inventors: Benjamin Wilson Casse; Brett John Huddart; Anton Kim GULLEY
Original assignee: Fisher and Paykel Healthcare Ltd
Current assignee: Fisher and Paykel Healthcare Ltd
Priority date: 2023-12-21
Filing date: 2024-12-20
Publication date: 2025-06-26
Anticipated expiration: 2026-06-21
Also published as: WO2025133998A8

Abstract

A method for controlling flow rate of gas comprising: delivering gas flow to patient at operating flow rate, and at intervals, receiving or determining, based on data from one or more sensors, first and second patient parameters indicative of patient's respiratory rate and heart rate, determining first status of respiratory rate based on first patient parameter and the first patient parameter received or determined at one or more previous intervals, determining second status of heart rate based on second patient parameter and the second patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on first and second status, and based on determining that operating flow rate be adjusted, adjusting operating flow rate by an increment, and based on determining that operating flow rate be maintained, maintaining operating flow rate at the present operating flow rate.

Description

RESPIRATORY SUPPORT CONTROL USING RESPIRATORY RATE AND HEART RATE

FIELD OF THE DISCLOSURE

The present disclosure relates to methods and systems for providing a respiratory flow therapy to a patient. In particular, the present disclosure relates to controlling operating parameters during use of an unsealed respiratory apparatus (i.e. open respiratory apparatus) by a patient, based on the patient’s measured respiratory rate and heart rate.

BACKGROUND

Breathing assistance apparatuses are used in various environments such as hospital, medical facility, residential care, or home environments to deliver a flow of gases to users or patients. A breathing assistance or respiratory therapy apparatus (collectively, “respiratory apparatus” or “respiratory devices”) may be used to deliver supplementary oxygen or other gases with a flow of gases, and/or a humidification apparatus to deliver heated and humidified gases. A respiratory apparatus may allow adjustment and control over characteristics of the gases flow, including flow rate and gases concentration.

SUMMARY

In a first aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status; and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate. In a second aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating the respiratory rate is stable and the second status indicating the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

The method of any of the first aspect or second aspect, may further have any one or more of the aspects or features defined herein.

In a third aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

In a fourth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.-

In a fifth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

In a sixth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

The respiratory therapy system of any of the third aspect, or fifth aspect, or the respiratory apparatus of the fourth aspect, or sixth aspect, may further have any one or more of the aspects or features defined herein. In a seventh aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to: receive or determine, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

In an eighth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to: receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

The respiratory therapy system of the seventh aspect, or the respiratory apparatus of the eighth aspect may further have any one or more of the aspects or features defined herein.

In a ninth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to, based on the first status and the second status, adjust the operating flow rate continually until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

The respiratory apparatus of the ninth aspect may further have any one or more of the aspects or features defined herein.

In a tenth aspect, the present disclosure broadly comprises a method for determining an operating flow rate of gas delivered to a patient, the method comprising: delivering a gas flow to the patient via a patient interface; at intervals, progressively applying a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on the first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on the second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining a first stable region corresponding to the first status indicating the respiratory rate is stable, the first stable region being subsequent to a first non-stable region corresponding to the first status indicating the respiratory rate is non-stable; determining a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being before a second non-stable region corresponding to the second status indicating the heart rate is non- stable; and determining a flow rate value that is within the first stable region and the second stable region as the operating flow rate for the gas flow.

The method of the tenth aspect may further have any one or more of the aspects or features defined herein.

In an eleventh aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, wherein the controller is further configured to, at intervals: progressively apply a plurality of flow rate values for the flow of gases; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determine a first status of the respiratory rate based at least on the first patient parameter and the first patient parameter received or determined at one or more previous intervals; determine a second status of the heart rate based at least on the second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to: determine a first stable region corresponding to the first status indicating the respiratory rate is stable, the first stable region being subsequent to a first non-stable region corresponding to the first status indicating the respiratory rate is non-stable; determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being before a second non- stable region corresponding to the second status indicating the heart rate is non-stable; and determine a flow rate value that is within the first stable region and the second stable region as an operating flow rate for the flow of gases.

The respiratory apparatus of the eleventh aspect may further have any one or more of the aspects or features defined herein.

In a twelfth aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; comparing the respiratory rate to a first threshold range associated with the respiratory rate; comparing the heart rate to a second threshold range associated with the heart rate; and in response to determination of at least one of the respiratory rate being outside of the first threshold range or the heart rate being outside of the second threshold range, adjusting the flow rate to effect the respiratory rate within the first threshold range and the heart rate within the second threshold range.

The method of the twelfth aspect may further have any one or more of the aspects or features defined herein.

In a thirteenth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; compare the respiratory rate to a first threshold range associated with the respiratory rate; compare the heart rate to a second threshold range associated with the heart rate; and in response to determination of at least one of the respiratory rate being outside of the first threshold range or the heart rate being outside of the second threshold range, adjust the flow rate to effect the respiratory rate within the first threshold range and the heart rate within the second threshold range.

The respiratory apparatus of the thirteenth aspect may further have any one or more of the aspects or features defined herein.

In a fourteenth aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: at intervals, progressively increasing the flow rate by a regular increment, at each of the intervals, receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining, based on the respiratory rate and the heart rate received or determined at the intervals, the flow rate that satisfies at least one condition of: a minimum respiratory rate, or a minimum heart rate, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold, and controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

The method of the fourteenth aspect may further have any one or more of the aspects or features defined herein.

In a fifteenth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: at intervals, progressively increase the flow rate by a regular increment, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine, based on the respiratory rate and the heart rate received or determined at the intervals, the flow rate that satisfies at least one condition of: a minimum respiratory rate, or a minimum heart rate, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold, and control the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

The respiratory apparatus of the fifteenth aspect may further have any one or more of the aspects or features defined herein.

In a sixteenth aspect, the present disclosure broadly comprises a method for controlling a flow generator of a respiratory apparatus to provide a flow of gases to a user, the method comprising: continuously receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; operating the flow generator in a first mode comprising: generating the flow of gases at an initial flow rate; increasing the initial flow rate by a defined increment over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, receiving or determining, based on data from the one or more sensors, the respiratory rate and the heart rate; determining, based on the respiratory rate and the heart rate received or determined for the range of flow rates, a desired respiratory rate and a desired heart rate, and in response to determining the desired respiratory rate and the desired heart rate, operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate.

The method of the sixteenth aspect may further have any one or more of the aspects or features defined herein.

In a seventeenth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, the controller being further configured to: continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; operate the flow generator in a first mode to: generate the flow of gases at an initial flow rate; increase the initial flow rate by a defined increment over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is to be delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, receive or determine, based on data from the one or more sensors, the respiratory rate and the heart rate; determine, based on the respiratory rate and the heart rate received or determined for the range of flow rates, a desired respiratory rate and a desired heart rate, and in response to the desired respiratory rate and the desired heart rate being determined, operate the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate.

The respiratory apparatus of the seventeenth aspect may further have any one or more of the aspects or features defined herein.

In an eighteenth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, wherein the controller is further configured to repeat the steps throughout a therapy session for the respiratory therapy to adjust or maintain the operating flow rate throughout the therapy session.

The respiratory apparatus of the eighteenth aspect may further have any one or more of the aspects or features defined herein. In a nineteenth aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indictive of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index ; and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate depending on the cardiorespiratory index, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

In a twentieth aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining a status of the patient based at least on said cardiorespiratory index and the cardiorespiratory index determined at one or more previous intervals; based on the status indicating the respiratory rate and/or the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said respiratory rate, said heart rate and cardiorespiratory index, and determine, at further intervals, said status; and based on the status indicating the respiratory rate and/or the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the status indicates that the respiratory rate and/or the heart rate is stable.

In a twenty-first aspect, the present disclosure broadly comprises a method for determining an operating flow rate of gas delivered to a patient, the method comprising: delivering a gas flow to the patient via a patient interface; at intervals, progressively applying a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining a status of the respiratory rate based at least on the cardiorespiratory index and the cardiorespiratory index received or determined at one or more previous intervals; determining a first stable region corresponding to the status indicating the respiratory rate is stable, the stable region being subsequent to a nonstable region corresponding to the status indicating the respiratory rate is non-stable and/or determining a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being subsequent to a second non-stable region corresponding to the status indicating the heart rate is non-stable; determining a flow rate value that is within the first stable region and/or the second stable region as the operating flow rate for the gas flow.

In a twenty-second aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; comparing the cardiorespiratory index to a threshold range associated with the cardiorespiratory index; and in response to determination of the cardiorespiratory index being outside of the threshold range, adjusting the flow rate to effect the cardiorespiratory index within the threshold range.

In a twenty-third aspect, the present disclosure broadly comprises a method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: at intervals, progressively increasing or decreasing the flow rate by a regular increment or decrement, at each of the intervals, receiving or determining, based on data from one or more sensors, a respiratory rate of the user and/or a heart rate of the user; at each of the intervals, determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; determining, based on the cardiorespiratory index determined at the intervals, the flow rate that satisfies at least one condition of: a minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the cardiorespiratory index satisfying a threshold, and controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

In a twenty-fourth aspect, the present disclosure broadly comprises a method for controlling a flow generator of a respiratory apparatus to provide a flow of gases to a user, the method comprising: continuously receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; operating the flow generator in a first mode comprising: generating the flow of gases at an initial flow rate; increasing and/or decreasing the initial flow rate by a defined increment or decrement over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, determining, based on data from the one or more sensors, the cardiorespiratory index; determining, based on the cardiorespiratory index determined for the range of flow rates, a desired cardiorespiratory index, and in response to determining the desired cardiorespiratory index , operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index.

The method of any of the nineteenth aspect, or twentieth aspect, or twenty-first aspect, or twenty-second aspect, or twenty-fourth aspect, may further have any one or more of the aspects or features defined herein.

In a twenty-fifth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, perform the steps of: receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indictive of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index ; and based on determining that said operating flow rate be adjusted, operate the flow controller to adjust the operating flow rate depending on the cardiorespiratory index, and based on determining that said operating flow rate be maintained, operate the flow controller to maintain the operating flow rate at the present operating flow rate.

In a twenty-sixth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, operate the flow generator to progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the patient based at least on said cardiorespiratory index and the cardiorespiratory index determined at one or more previous intervals; based on the status indicating the respiratory rate and/or the heart rate is stable, operate the flow generator to maintain the operating flow rate, and perform an iterative process of continuing to receive or determine said respiratory rate, said heart rate and cardiorespiratory index, and determine, at further intervals, said status; and based on the status indicating the respiratory rate and/or the heart rate is no longer stable, operate the flow controller to adjust the operating flow rate at said further intervals until the status indicates that the respiratory rate and/or the heart rate is stable.

In a twenty-seventh aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: at intervals, operate the flow generator to progressively apply a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the respiratory rate based at least on the cardiorespiratory index and the cardiorespiratory index received or determined at one or more previous intervals; determine a first stable region corresponding to the status indicating the respiratory rate is stable, the stable region being subsequent to a nonstable region corresponding to the status indicating the respiratory rate is non-stable and/or determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being subsequent to a second non-stable region corresponding to the status indicating the heart rate is non-stable; determine a flow rate value that is within the first stable region and/or the second stable region as the operating flow rate for the gas flow.

In a twenty-eighth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and perform a process comprising: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; compare the cardiorespiratory index to a threshold range associated with the cardiorespiratory index; and in response to determination of the cardiorespiratory index being outside of the threshold range, operate the flow generator to adjust the flow rate to effect the cardiorespiratory index within the threshold range.

In a twenty-nineth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at a flow rate; and perform a process comprising: at intervals, operate the flow generator to progressively increase or decrease the flow rate by a regular increment or decrement, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and/or a heart rate of the user; at each of the intervals, determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; determine, based on the cardiorespiratory index determined at the intervals, the flow rate that satisfies at least one condition of: a minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the cardiorespiratory index satisfying a threshold, and operating the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

In a thirtieth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; operate the flow generator in a first mode comprising: generate the flow of gases at an initial flow rate; increase and/or decrease the initial flow rate by a defined increment or decrement over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, determine, based on data from the one or more sensors, the cardiorespiratory index; determine, based on the cardiorespiratory index determined for the range of flow rates, a desired cardiorespiratory index , and in response to determining the desired cardiorespiratory index , operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index.

The respiratory apparatus of any of the twenty-fifth aspect, or twenty-sixth aspect, or twentyseventh aspect, or twenty-eighth aspect, or twenty-nineth aspect, or thirtieth aspect, may further have any one or more of the aspects or features defined herein.

In another aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for high flow respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; a controller, wherein the controller is configured to control the operating flow rate of the flow generator based on a received or determined first patient parameter indicative of a respiratory rate of a patient and a received or determined second patient parameter indicative of a heart rate of the patient. The gases delivered to the patient are flow controlled in high flow therapy, and typically humidified and delivered at a flow rate that meets or exceeds inspiratory demand of the patient.

One or more aspects of the present disclosure may, in some configurations, use one or more sensors configured to be attached to or located near to the patient to measure the first patient parameter and the second patient parameter. The one or more sensors may be non-contact sensors that communicate wirelessly, and may be located under a patient’s mattress or behind a patient’s chair cushion.

In another aspect, the present disclosure relates to an electronically-implemented method comprising software code or coded instructions that are executable or implemented by a computer, processor, or controller to carry out any one or more of the methods or aspects described above.

In another aspect, the present disclosure broadly comprises a non-transitory computer-readable medium having stored thereon computer executable instructions that, when executed on a processing device or devices, cause the processing device or devices to perform or execute any one or more of the methods or aspects described above.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.

Figure 1 shows schematically a respiratory system configured to provide a respiratory therapy to a patient.

Figure 2 illustrates a block diagram of a control system interacting with and/or providing control and direction to components of a respiratory system.

Figure 3 illustrates a block diagram of an example controller.

Figure 4 shows schematically a respiratory system configured to provide a respiratory therapy to a patient.

Figure 5 illustrates a block diagram of a control system interacting with and/or providing control and direction to components of a respiratory system. Figure 6 shows a flow diagram of an embodiment of an operating flow rate determination process.

Figures 7 to 10 show graphical representations of examples of respiratory rate versus flow rate relationship.

Figures 11 and 12 show graphical representation of examples of heart rate versus flow rate relationship.

Figure 13 to 21 show graphical representations of examples of respiratory rate and heart rate versus flow rate relationship.

Figure 22 shows a flow diagram of an embodiment of an operating flow rate determination process.

DETAILED DESCRIPTION

Although certain examples are described below, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed examples and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosure herein disclosed should not be limited by any particular examples described below.

A respiratory assistance system including a humidification apparatus may be used to deliver heated and humidified respiratory gases to a patient through a conduit and a patient interface. The respiratory assistance system can provide a number of therapies for patients requiring respiratory support. One of the therapies includes providing a high flow therapy in which gases delivered to the patient are flow controlled and humidified and are delivered at a flow rate that meets or exceeds the inspiratory demand of the patient. For example, the flow rate may be above 15 L/min and which is delivered at a substantially constant flow rate during inspiration and expiration, but is be adjusted at intervals to find an optimal flow rate. An optimal flow rate may correspond to a local minimum for a patient’s respiratory rate and/or heart rate, or an index based on both of these.

In high flow therapy, the respiratory support system delivers relatively high flows of gases through a nasal interface, which may be unsealed. The flow of gases can be in the range of 5 L/min to 120 L/min. In some examples, the flow of gases can be in the range of 10 L/min to 120 L/min. In some examples, the flow of gases can be in the range of 20 L/min to 120 L/min. In some examples, the flow of gases is in the range of 30 L/Min to 50 L/min. In some examples, the flow rate of gases can be as high as 60 L/min. In some examples, the flow rate is greater than 60 L/min, but less than 120 L/min. In other examples, the flow rate is 120 L/min or higher. The respiration assistance system can adjust the flow rate of gases during the treatment through a control system. A discussion of high flow therapy and how the flow rate can be changed in a respiratory assistance system can be found in PCT Pub. No. WO 2015/033288, titled “Improvements to Flow Therapy”, which is hereby incorporated by reference in its entirety.

The flow rate in the high flow therapies may be a function of patient condition and can vary during the treatment. A clinician or patient may not be able to determine the value of the flow rate for the respiratory assistance system to provide the optimal therapy and comfort. Care providers often do not know proper flow rates for particular patients and tend to set flow rates too low or too high to be clinically optimal. Care providers also often do not know how to gauge the effectiveness of the therapy or how long they should wait to determine effectiveness.

Accordingly, the present disclosure provides methods and systems for controlling operating parameters of the device, specifically flow rate and/or oxygen concentration level, for a given patient. The methods can be performed by a control system of the device. The respiratory assistance device and system discussed below include a control system implemented using a controller for controlling the operating parameters of the device. The control system can control the operating flow rate and/or oxygen concentration level of gas delivered to a patient automatically over the time of therapy and based on changes in patient conditions. Thus, the control system may advantageously improve the efficacy of the high flow therapy and reduce the probability of the patient requiring more invasive treatment such as invasive mechanical ventilation. A flow rate and/or oxygen concentration level control method for high flow respiratory therapy may help in a patient spending less time with a flow rate set too high or too low for their immediate breathing support requirements over the course of the therapy.

Flow rate is likely to affect a number of physiological and clinical parameters including work of breathing, end tidal CO2, respiration rate, heart rate, thoraco-abdominal phase, and other parameters of clinical relevance. The control system and method described can automatically control an operating high flow respiratory therapy flow rate based at least on a first patient parameter indicative of the patient’s respiratory rate and/or a second patient parameter indicative of the patient’s heart rate. Physiological parameters such as respiratory rate and/or heart rate may provide information on whether a patient’s condition is worsening or improving. Physiological parameters such as respiratory rate and/or heart rate may also provide information on when a patient has stabilised after being placed on high flow therapy. Using respiratory rate and/or heart rate can thus aid in controlling operating parameters relating to the provision of high flow respiratory therapy. Respiratory rate and/or heart rate can provide a means to identify optimal or otherwise acceptable operating parameters or therapy settings when a patient is receiving high flow therapy.

Controlling operating parameters based on physiological parameters typically involves monitoring how a physiological parameters such as respiratory rate and/or heart rate changes or reacts in order to determine optimal operating parameters for high flow therapy. If the operating parameters are changed manually by a clinician or other person in response to measured physiological parameters, it can be a very time-consuming process to reach optimal operating parameters. It is unlikely that the operating parameters are set at optimal or otherwise acceptable conditions due to this requirement of a long titration duration, as clinicians will not have the time needed to do so.

Some physiological parameters used can also take an impractically long time to change in response to therapy changes or to a worsening patient condition. One example of this is SpO2, which is widely used as a physiological parameter. Generally, when a patient’s condition worsens, the body initially keeps SpO2 levels stable by increasing minute ventilation and providing more oxygen to the lungs. As such, SpO2 levels may only be affected after a significant delay and/or once the patient’s condition has greatly deteriorated. In such cases, it is impractical to use these physiological parameters for therapy parameter control, which requires minimised response delay.

There is thus a need for a control system and method that can automatically control operating parameters of a respiratory therapy device based on a measured patient condition. Such a system should be able to titrate the parameters to optimal or otherwise acceptable values when a patient is using the therapy. The patient condition should be measured using a physiological parameter that provides early-indication of changes in patient condition, and that is accurately and continuously measured. The control system’s automatic control of the operating parameters of the respiratory therapy device can help to deliver optimal respiratory therapy to the patient, and can help to reduce their respiratory rate and/or heart rate, which allows the patient to be more relaxed and reduces their work of breathing, or in other terms the physical load of breathing hard. The control system can also assist in faster identification of therapy success or failure. For example, it may be advantageous to know that high flow therapy is not working on a particular patient earlier rather than later. The control system may compare the physiological parameters of the patient as a function of flow rate to expected predetermined parameters for determining effectiveness of the therapy.

Delivery of optimal respiratory therapy by controlling the operating parameters of a respiratory therapy device can help to reduce a patient’s respiratory distress and to reduce their work of breathing i.e. the effort it takes them to breathe. As will be discussed, the respiratory rate and/or heart rate of the patient can provide an indication of their work of breathing. In particular, a higher respiratory rate and/or heart rate may be indicative of higher work of breathing. The present disclosure relates to controlling a respiratory apparatus based on respiratory rate and/or heart rate to reduce work of breathing.

The control system discussed may generate an indication of the operating parameters such as flow rate or oxygen concentration level for display to a physician. The control system may warn the clinician if the therapy is not efficacious for the particular patient based on the sensitivity or insensitivity of clinical and physiological parameters (such as a measured respiratory rate and/or heart rate to the operating parameters. The present disclosure may detect if the respiratory therapy is not efficacious and indicate this to a clinician. The clinician can then make a decision to escalate the patient to a different therapy e.g. Bi-Level pressure therapy or invasive ventilation.

1. Overview of Example Respiratory Apparatus

Examples of the methods and processes for respiratory control will be described in the context of an example respiratory apparatus or breathing assistance apparatus (these terms are used interchangeably) 100 that is configured or operable to provide nasal high flow therapy via an unsealed patient interface. This is intended as a non-limiting example. It will be appreciated that the methods and processes may be applied to other respiratory apparatus and/or to other modes of operation and/or modes of therapy delivered by such apparatus. A schematic representation of the example respiratory system 10 is provided in Figure 1. The respiratory system 10 includes a respiratory apparatus (generally shown in the dashed box 60) having a flow generator 50B and a controller 19. The respiratory apparatus 60 may further include a humidifier 52. The respiratory apparatus 60 may include an integrated flow generator 50B and humidifier 52 (e.g., the flow generator 50B and the humidifier 52 may be arranged in the same housing of the respiratory apparatus 60) as illustrated in Figure 1, or the humidifier 52 may be in a separate housing. A delivery conduit 16 and a patient interface 51 may be provided, as part of the respiratory system 10, to fluidly couple to the respiratory apparatus 60.

The controller 19 may include one or more control systems, e.g., control system 920 of Figure 2 to be described further below, and/or may have a configuration similar to the controller 600 of Figure 3 to be described further below. The controller 19 may have controller function as described further below in the context of the control system 920 of Figure 2 or the controller 600 of Figure 3.

The respiratory system 10 comprises a flow source 50 for providing a high flow gas 31 such as air, oxygen, air blended with oxygen, or a mix of air and/or oxygen and one or more other gases. The breathing assistance apparatus 60 can have a connection for coupling to a flow source. As such, the flow source might be considered to form part of the apparatus 60 or be separate to it, depending on context, or even part of the flow source forms part of the apparatus 60, and part of the flow source falls outside of the apparatus 60. In short, depending on the configuration (some components may be optional), the system 10 can include a combination of components selected from the following:

• a flow source,

• humidifier for humidifying the gas-flow,

• conduit (e.g., dry line or heated breathing tube),

• patient interface,

• non-return valve,

• filter.

The system 10, including the apparatus 60, will now be described in more detail. The flow source could be an in-wall supply of oxygen, a tank of oxygen 50A, a tank of other gas and/or a high flow apparatus with a flow generator 50B. Figure 1 shows a flow source 50 with a flow generator 50B, with an optional air inlet 50C and optional connection to an oxygen (02) source (such as tank or 02 generator) 50A via a shut off valve and/or regulator and/or other gas flow control 50D, but this is just one option. The flow generator 50B can control flows delivered to the user or patient 56 using one or more valves, or optionally the flow generator 50B can comprise a blower. The flow source 50 could be one or a combination of a flow generator 50B, 02 source 50A, air source 50C as described. The flow source 50 is shown as part of the apparatus 60, although in the case of an external oxygen tank or in-wall source, it may be considered a separate component, in which case the apparatus 60 has a connection port to connect to such flow source. The flow source 50 provides a (preferably high) flow of gas that can be delivered to a patient 56 via a delivery conduit 16, and a patient interface 51.

The patient interface 51 may be an unsealed (non-sealing) interface (for example, when used in high flow therapy) such as a non-sealing nasal cannula. In some embodiments, the patient interface 51 is a non- sealing patient interface which would, for example, help to prevent barotrauma (e.g., tissue damage to the lungs or other organs of the respiratory system due to difference in pressure relative to the atmosphere). The patient interface 51 may be a nasal cannula with a manifold and nasal prongs, or any other suitable types of non-sealing patient interface. The flow source 50 could provide a base gas flow rate of between, e.g., 0.5 litres/min and 375 litres/min, or any range within that range, or even ranges with higher or lower limits. Details of the ranges and nature of flow rates will be described later.

A humidifier 52 can optionally be provided between the flow source 50 and the patient 56 to provide humidification of the delivered gas. One or more sensors 53A, 53B, 53C, 53D such as flow, oxygen fraction, pressure, humidity, temperature or other sensors can be placed throughout the system 10 and/or at, on or near the patient 56. Alternatively, or additionally, sensors from which such parameters can be derived could be used. In addition, or alternatively, the sensors 53A-53D can be one or more physiological sensors for sensing patient physiological parameters such as, heart rate, oxygen saturation, partial pressure of oxygen in the blood, respiratory rate, partial pressure of carbon dioxide (CO2) in the blood. Alternatively, or additionally, sensors from which such parameters can be derived could be used. Other patient sensors could comprise EEG sensors, torso bands to detect breathing, and any other suitable sensors. In some configurations the humidifier 52 may be optional, or it may be preferred due to the advantages of humidified gases helping to maintain the condition of the airways. One or more of the sensors 53A-53D might form part of the apparatus 60, or be external thereto, with the apparatus 60 having inputs for any external sensors. The sensors (e.g., 53A-53D) can be coupled to or send their output to a controller 19.

In some examples one or more of the sensors may be non-contact sensors which are positioned away from the patient but adapted to sense parameters such as respiratory rate and/or heart rate. For example, one or more non-contact sensors may be positioned under a mattress of a patient and adapted to provide signals indicating of the respiratory rate and/or heart rate of the patient whilst the patient is lying on the mattress. The non-contact sensor or sensors may be oriented vertically and placed under the back rest of a chair or couch used by the patient. The or each non-contact sensor may be aligned with the patient’s spine. Such sensors may communicate wirelessly with other parts of the respiratory system 10. In some examples, one or more sensors may be an electromechanical film sensor or a piezoelectric sensor.

In some configurations, the respiratory system 10 can include a sensor 14 for measuring the oxygen fraction of air the patient 56 inspires. In some examples, the sensor 14 can be placed on the patient interface 51, to measure or otherwise determine the fraction of oxygen proximate (at/near/close to) the patient’s mouth and/or nose. In some configurations, the output from the sensor 14 is sent to the controller 19 to assist control of the respiratory apparatus 60 to alter operation accordingly. The controller 19 is coupled to the flow source 50, humidifier 52 and sensor 14. In some configurations, the controller 19 controls these and other aspects of the respiratory apparatus 60 and the respiratory system 10 as described herein. In some examples, the controller 19 can operate the flow source 50 to provide the delivered flow of gas 31 at a desired flow rate high enough to meet or exceed a user’s (i.e., patient’s) inspiratory demand. The flow rate provided is sufficient that ambient gases are not entrained as the user (i.e., patient) 56 inspires. In some configurations, the sensor 14 can convey measurements of oxygen fraction at the patient mouth and/or nose to a user, who can input the information to the respiratory apparatus 60 / controller 19.

An optional non-return valve 23 may be provided in the breathing conduit 16. A filter or filters may be provided at the air inlet 50C and/or inlets to the flow generator 50B to filter the incoming gases before they are pressurized into a high flow gas 31 by to the flow generator 50B. The breathing assistance system 10 could be an integrated or a separate component-based arrangement. In some configurations, the system 10 and/or the apparatus 60 could be a modular arrangement of components. Furthermore, the system 10 and/or the apparatus 60 may just comprise some of the components shown, not necessarily all are essential. The conduit 16 and patient interface 51 are separate from the respiratory apparatus 60. Breathing assistance apparatus will be broadly considered herein to comprise anything that provides a flow rate of gas to a patient. The breathing assistance apparatus can be part of a respiratory system. Some such apparatus and systems may include a detection system that can be used to determine if the flow rate of gas meets inspiratory demand.

The respiratory apparatus 60 can include a main device housing (not shown). The housing can contain the flow generator 50B that can be in the form of a motor/impeller arrangement, an optional humidifier or humidification chamber 52, a controller 19, and an input/output (I/O) user interface 54. The user interface 54 can include a display and input device(s) such as button(s), a touch screen (e.g., an LCD touch screen), a combination of a touch screen and button(s), or the like. The controller 19 can include one or more hardware and/or software processors and can be configured or programmed to control the components of the respiratory apparatus 60, including but not limited to operating the flow generator 50B to create a flow of gases 31 for delivery to a patient 56, operating the humidifier or humidification chamber 52 (if present) to humidify and/or heat the gases flow 31, receiving user input from the user interface 54 for reconfiguration and/or user-defined operation of the respiratory apparatus 60, and outputting information (for example on the display) to the user. The user can be a patient, healthcare professional, or others.

In one configuration, the user interface 54 of the respiratory apparatus 60 may comprise a removable display screen or touch screen.

With continued reference to Figure 1, a patient breathing conduit 16 can be coupled to a gases flow outlet (gases outlet or patient outlet port) 21 in the main device housing of the respiratory apparatus 60, and be coupled to a patient interface 51, such as a non-sealing interface like a nasal cannula with a manifold and nasal prongs. The patient breathing conduit 16 can also be a tracheostomy interface, or other unsealed interfaces. The gases flow 31 can be generated by the flow generator 50B, and may be humidified, before being delivered to the patient 56 via the patient breathing conduit 16 through the patient interface 51. The controller 19 can control the flow generator 50B to generate a gases flow 31 of a desired flow rate, and/or one or more valves to control mixing of air and oxygen or other breathable gas. The controller 19 can control a heating element in or associated with the humidification chamber 52, if present, to heat the gases to a desired temperature that achieves a desired level of temperature and/or humidity for delivery to the patient 56. The patient breathing conduit 16 can have a heating element, such as a heater wire, to heat gases flow 31 passing through to the patient 56. The heating element can also be under the control of the controller 19.

The humidifier 52 of the apparatus 60 is configured to combine or introduce humidity with or into the gases flow 31. Various humidifier 52 configurations may be employed. In one configuration, the humidifier 52 can comprise a humidification chamber that is removable. For example, the humidification chamber may be partially or entirely removed or disconnected from the flow path and/or apparatus 60. By way of example, the humidification chamber may be removed for refilling, cleaning, replacement and/or repair for example. In one configuration, the humidification chamber may be received and retained by or within a humidification compartment or bay of the apparatus 60, or may otherwise couple onto or within the housing of the apparatus 60.

The humidification chamber of the humidifier 52 may comprise a gases inlet and a gases outlet to enable connection into the gases flow path of the apparatus 60. For example, the flow of gases 31 from the flow generator 50B is received into the humidification chamber via its gases inlet and exits the chamber via its gases outlet, after being heated and/or humidified.

The humidification chamber contains or receives a volume of liquid, typically water or similar. In operation, the liquid in the humidification chamber is controllably heated by one or more heaters or heating elements associated with the chamber to generate water vapour or steam to increase the humidity of the gases flowing through the chamber.

In one configuration, the humidifier 52 is a pass-over humidifier. In another configuration, the humidifier 52 may be a non-pass-over humidifier. In one configuration, the humidifier 52 may comprise a heater plate, for example, associated or within a humidification bay that the chamber sits on for heating. The chamber may be provided with a heat transfer surface, e.g., a metal insert, plate or similar, in the base or other surface of the chamber that interfaces or engages with the heater plate of the humidifier 52.

In another configuration, the humidification chamber may comprise an internal heater or heater elements inside or within the chamber. The internal heater or heater elements may be integrally mounted or provided inside the chamber, or may be removable from the chamber.

The humidification chamber may be any suitable shape and/or size. The location, number, size, and/or shape of the gases inlet and gases outlet of the chamber may be varied as required. In one configuration, the humidification chamber may have a base surface, one or more side walls extending up from the base surface, and an upper or top surface. In one configuration, the gases inlet and gases outlet may be position on the same side of the chamber. In another configuration, the gases inlet and gases outlet may be on different surfaces of the chamber, such as on opposite sides or locations, or other different locations.

In some configurations, the gases inlet and gases outlet may have parallel flow axes. In some configurations, the gases inlet and gases outlet may be positioned at the same height on the chamber.

The system 10, including the apparatus 60, can use ultrasonic transducer(s), flow sensor(s) such as a thermistor flow sensor, pressure sensor(s), temperature sensor(s), humidity sensor(s), or other sensors, in communication with the controller 19, to monitor characteristics of the gases flow 31 and/or operate the apparatus 60 in a manner that provides suitable therapy. The gases flow characteristics can include gases concentration, flow rate, pressure, temperature, humidity, or others. The sensors 53A, 53B, 53C, 53D, 14, such as pressure, temperature, humidity, and/or flow sensors, can be placed in various locations in the main device housing, the patient conduit 16, and/or the patient interface 51. The controller 19 can receive output from the sensors 53A, 53B, 53C, 53D, 14 to assist it in operating the respiratory apparatus 60 in a manner that provides suitable therapy, such as to determine a suitable target temperature, flow rate, and/or pressure of the gases flow. Providing suitable therapy can include meeting or exceeding a patient’s inspiratory demand. In the illustrated embodiment, sensors 53 A, 53B, and 53C are positioned in the housing of the apparatus 60, sensor 53D in the patient conduit 16, and sensor 14 in the patient interface 51.

The respiratory system 10 may include a sensor arrangement or a sensor module. The sensor arrangement or module may include a plurality of sensor types. The respiratory system 10 may include one or more of a flow (or flow rate) sensor, a pressure sensor, a temperature sensor, a humidity sensor and an oxygen (02) sensor. The 02 sensor may be an ultrasonic sensor. An ultrasonic sensor may be positioned in line with the flow and hence can be used as a flow sensor in addition to the 02 sensor. One non-limiting example of a flow rate sensor is a thermistor flow rate sensor as described in PCT Application Publication No. W02018/052320, filed 3 September 2017, which is incorporated by reference herein in its entirety. Another non-limiting example of a flow rate sensor is an acoustic flow rate sensor as described in PCT Application Publication No. WO2017/095241, filed 2 December 2016, which is incorporated by reference herein in its entirety.

In some configurations, the gases flow rate may be measured using at least two different types of sensors. For example, a first type of sensor may include a thermistor flow rate sensor, and a second type of sensor may include an acoustic flow rate sensor. Readings from both the first and second types of sensors can be combined to determine a more accurate flow measurement. For example, a previously determined flow rate and one or more outputs from one of the types of sensor can be used to determine a predicted current flow rate. The predicted current flow rate can then be updated using one or more outputs from the other one of the first and second types of sensor, in order to calculate a final flow rate.

The apparatus 60 can include one or more communication modules to enable data communication or connection with one or more external devices or servers over a data or communication link or data network, whether wired, wireless or a combination thereof. In one configuration, for example, the apparatus 60 can include a wireless data transmitter and/or receiver, or a transceiver 15 to enable the controller 19 to receive data signals in a wireless manner from the operation sensors and/or to control the various components of the apparatus 60. The transceiver 15 or data transmitter and/or receiver module may have an antenna 15a as shown. In one example, the transceiver 15 may comprise a Wi-Fi modem. Additionally, or alternatively, the data transmitter and/or receiver 15 can deliver data to a remote patient management system (i.e., a remote server) or enable remote control of the apparatus 60. The apparatus 60 can include a wired connection, for example, using cables or wires, to enable the controller 19 to receive data signals from the operation sensors and/or to control the various components of the apparatus 60. The apparatus 60 may comprise one or more wireless communication modules. For example, the apparatus 60 may comprise a cellular communication module such as for example a 3G, 4G or 5G module. The module 15 may be or may comprise a modem that enables the apparatus 60 to communicate with a remote patient management system (not illustrated in the figures) using an appropriate communication network. The remote management system may comprise a single server or multiple servers or multiple computing devices implemented in a cloud computing network. The communication may be two-way communication between the apparatus 60 and a patient management system (e.g., a server) or other remote system. The apparatus 60 may also comprise other wireless communication modules such as, for example, a Bluetooth module and/or a Wi-Fi module. The Bluetooth and/or WiFi module allow the apparatus 60 to wirelessly send information to another device such as, for example, a smartphone or tablet or operate over a LAN (local area network) or Wireless LAN (WLAN). The apparatus 60 may additionally, or alternatively, comprise a Near Field Communication (NFC) module to allow for data transfer and/or data communication.

For example, data representing determined or calculated work of breathing (WoB) indicators may be communicated to a remote patient management system (i.e., a remote server). The remote patient management system may be a single server or a network of servers or a cloud computing system or other suitable architecture for operating a remote patient management system. The remote patient management system (i.e., a remote server) further includes memory for storing received data and various software applications or services that are executed to perform multiple functions. Then, for example, the remote patient management system (i.e., remote server) may communicate information or instructions to the apparatus 60, as part of the system 10, at least in part dependent on the data received. For example, the nature of the data received may trigger the remote server (or a software application running on the remote server) to communicate an alert, alarm, or notification to the apparatus 60. The remote patient management system may further store the received data for access by an authorised party such as a clinician or the patient or another authorized party. The remote patient management system may further be configured to generate reports in response to a request from an authorized party, and the work of breathing data may be included into the generated reports. The reports may further comprise other data or patient breathing parameters, e.g., respiratory rate or SpO2 and/or device parameters, e.g., flow rate, humidity level.

The respiratory apparatus 60 may comprise a high flow therapy apparatus. High flow therapy as discussed herein is intended to be given its typical ordinary meaning, as understood by a person of skill in the art, which generally refers to a respiratory system, having a high flow therapy apparatus, delivering a targeted flow of humidified respiratory gases via an intentionally unsealed patient interface with flow rates generally intended to meet or exceed inspiratory flow of a user. Typical patient interfaces include, but are not limited to, a nasal or tracheal patient interface. Typical flow rates for adults often range from, but are not limited to, about fifteen litres per minute (15 litres/min) to about sixty litres per minute (60 litres/min) or greater. Typical flow rates for paediatric users (such as neonates, infants and children) often range from, but are not limited to, about one litre per minute per kilogram of user weight to about three litres per minute per kilogram of user weight or greater.

High flow therapy can also optionally include gas mixture compositions including supplemental oxygen and/or administration of therapeutic medicaments.

High flow therapy is often referred to as nasal high flow (NHF), humidified high flow nasal cannula (HHFNC), high flow nasal oxygen (HFNO), high flow therapy (HFT), or tracheal high flow (THF), among other common names. For example, in some configurations, for an adult patient, ‘high flow therapy’ may refer to the delivery of gases to a patient at a flow rate of greater than or equal to about 10 litres per minute (10 LPM), such as between about 10 LPM and about 100 LPM, or between about 15 LPM and about 95 LPM, or between about 20 LPM and about 90 LPM, or between about 25 LPM and about 85 LPM, or between about 30 LPM and about 80 LPM, or between about 35 LPM and about 75 LPM, or between about 40 LPM and about 70 LPM, or between about 45 LPM and about 65 LPM, or between about 50 LPM and about 60 LPM. In some configurations, for a neonatal, infant, or child patient, ‘high flow therapy’ may refer to the delivery of gases to a patient at a flow rate of greater than 1 LPM, such as between about 1 LPM and about 25 LPM, or between about 2 LPM and about 25 LPM, or between about 2 LPM and about 5 LPM, or between about 5 LPM and about 25 LPM, or between about 5 LPM and about 10 LPM, or between about 10 LPM and about 25 LPM, or between about 10 LPM and about 20 LPM, or between about 10 LPM and 15 LPM, or between about 20 LPM and 25 LPM. A high flow therapy apparatus with an adult patient, a neonatal, infant, or child patient, may deliver gases to the patient at a flow rate of between about 1 LPM and about 100 LPM, or at a flow rate in any of the sub-ranges outlined above.

High flow therapy can be effective in meeting or exceeding the patient's inspiratory demand, increasing oxygenation of the patient and/or reducing the work of breathing. Additionally, high flow therapy may generate a flushing effect in the nasopharynx such that the anatomical dead space of the upper airways is flushed by the high incoming gases flow. The flushing effect can create a reservoir of fresh gas available for each and every breath, while minimizing rebreathing of carbon dioxide, nitrogen, etc. High flow therapy can also increase expiratory time of the patient due to pressure during expiration. This in turn reduces the respiratory rate and/or heart rate of the patient.

The flow rate may be set by a clinician to achieve flushing of the patient’s upper airways and/or meet or exceed a patient’s inspiratory demand and/or provide at least some of the advantages of high flow therapy (HFT) described herein.

The patient interface for use in a high flow therapy can be a non-sealing interface to prevent barotrauma, which can include tissue damage to the lungs or other organs of the patient’s respiratory system due to difference in pressure relative to the atmosphere. The patient interface can be a nasal cannula with a manifold and nasal prongs, and/or an unsealed tracheostomy interface, or any other suitable types of non-sealing patient interface.

The respiratory apparatus or device 60 can have air and oxygen (or alternative auxiliary gas) inlets in fluid communication with a motor of the respiratory apparatus 60 to enable the motor to deliver air, oxygen (or alternative auxiliary gas), or a mixture thereof to the humidification chamber and thereby to the patient.

The respiratory apparatus 60 may include a connector arrangement with one or more connectors, for example, USB or other suitable connectors, for coupling of an alarm, a pulse oximetry port, and/or other suitable accessories.

The respiratory apparatus 60 may include an electrical connector through which mains electricity or battery power may be provided to power the respiratory apparatus 60. The respiratory apparatus 60 may further include a battery or an internal power source that can power the apparatus 60 for a set period of time if the mains are disconnected.

1.1 Control System

Figure 2 illustrates a block diagram 900 of an example control system 920 (which can, for example, be the controller 19 in Figure 1) that can detect patient conditions and control operation of the respiratory system including the gases source. The control system 920 can manage a flow rate of the gases flowing through the respiratory system as is the gases are delivered to a patient. For example, the control system 920 can increase or decrease the flow rate by controlling an output of a motor speed of the blower (hereinafter also referred to as a “blower motor”) 930 or an output of a valve 932 in a blender. The control system 920 can automatically determine a set value or a personalized value of the flow rate for a particular patient as discussed below. The flow rate can be optimized by the control system 920 to improve patient comfort and therapy.

The control system 920 can also generate audio and/or display/visual outputs 938, 939. For example, the flow therapy apparatus can include a display and/or an audio output device (e.g., speaker). The display can indicate to the physicians any warnings or alarms generated by the control system 920. The display can also indicate control parameters that can be adjusted by the physicians. For example, the control system 920 can automatically recommend a flow rate for a particular patient. The control system 920 can also determine a respiratory state of the patient, including but not limited to generating a respiratory rate of the patient, and send it to the display, which will be described in greater detail below. The control system 920 can also generate a heart rate of the patient, and send it to the display.

The control system 920 can change heater control outputs to control one or more of the heating elements (for example, to maintain a temperature set point of the gases delivered to the patient). The control system 920 can also change the operation or duty cycle of the heating elements. The heater control outputs can include heater plate control output(s) 934 and heated breathing tube control output(s) 936.

The control system 920 can determine the outputs 930-939 based on one or more received inputs 901-916. The inputs 901-916 can correspond to sensor measurements received automatically by the controller 600 (shown in Figure 3). The control system 920 can receive sensor inputs including but not limited ts 901, flow rate sensor(s) inputs 902, motor speed inputs 903, pressure sensor(s) inputs 904, gas(s) fraction sensor(s) inputs 905, humidity sensor(s) inputs 906, pulse oximeter (for example, SpO2) sensor(s) inputs 907, stored or user parameter(s) 908, duty cycle or pulse width modulation (PWM) inputs 909, voltage(s) inputs 910, current(s) inputs 911, acoustic sensor(s) inputs 912, power(s) inputs 913, resistance(s) inputs 914, CO2 sensor(s) inputs 915, and/or spirometer inputs 916. The control system 920 can receive inputs from the user or stored parameter values in a memory 624 (shown in Figure 3). The control system 920 can dynamically adjust flow rate for a patient over the time of their therapy. The control system 920 can continuously detect system parameters and patient parameters. A person of ordinary skill in the art will appreciate based on the disclosure herein that any other suitable inputs and/or outputs can be used with the control system 920.

1.2 Controller

Figure 3 illustrates a block diagram of an embodiment of a controller 600 (which can, for example, be the controller 19 in Figure 1). The controller 600 can include programming instructions for detection of input conditions and control of output conditions. The programming instructions can be stored in the memory 624 of the controller 600. The programming instructions can correspond to the methods, processes and functions described herein. The programming instructions can be executed by one or more hardware processors 622 of the controller 600. The programming instructions can be implemented in C, C++, JAVA, or any other suitable programming languages. Some or all of the portions of the programming instructions can be implemented in application specific circuitry 628 such as ASICs and FPGAs.

The controller 600 can also include circuits 628 for receiving sensor signals. The controller 600 can further include a display 630 for transmitting status of the patient and the respiratory assistance system. The display 630 can also show warnings and/or other alerts. The display 630 can be configured to display characteristics of sensed gas(es) in real time or otherwise. The controller 600 can also receive user inputs via the user interface such as display 630. The user interface can include button(s) and/or dial(s). The user interface can comprise a touch screen.

2. Examples of operating parameter control

Figure 4 shows a schematic of an example respiratory assistance system 2200, similar to the respiratory assistance system 10 shown in Figure 1. The respiratory assistance system 2200 includes a gases source or respiratory apparatus 2202, a respiratory rate sensor 2215, a heart rate sensor 2217, and a patient intcrfa ' - , 2216 provides high flow therapy to the patient P. The patient interface 2216 may be referred to as a high flow therapy interface. The gases source or respiratory apparatus 2202 may be referred to as a high flow therapy device. The respiratory assistance system 2200 shown in Figure 4 may comprise any of the elements of the respiratory assistance system 10 in Figure 1. The patient interface 2216 in this example is an unsealed nasal cannula.

The respiratory rate sensor 2215 may comprise one or more sensors. The one or more respiratory rate sensors 2215 may be one or more sensors configured to be attached to or located near to the patient P. Each of the one or more sensors 2215 are configured to measure a first patient parameter indicative of the patient’s respiratory rate. In an example, one or more of the wearable sensors may be a body mounted respiratory rate sensor.

The heart rate sensor 2217 may comprise one or more sensors. The one or more heart rate sensor 2217 may be one or more sensors configured to be attached to or located near to the patient P. Each of the one or more sensors 2217 are configured to measure a second patient parameter indicative of the patient’s heart rate. In an example, one or more of the wearable sensors may be a body mounted heart rate sensor.

The respiratory rate sensor 2215 and the heart rate sensor 2217 may be different sensors.

In some examples, the same sensor may function as the respiratory rate sensor 2215 and the heart rate sensor 2217.

The gases source 2202 may include a flow generator or source 2224 that can create a flow of respiratory gases to be provided to the humidification apparatus 2224. In an example, the flow source 2224 is a blower. However, the flow source 2224 is not limited to a blower and can include a flow meter, a blender, flow mode from a ventilator, or any other flow generating device. Other flow sources known to those of skill in the art can also be used with any of the examples of the present disclosure as further discussed below.

The gases source 2202 may include a controller 2226 that can control the operation of the flow source 2224. For example, the controller 2226 can execute or implement a control system described more in detail below to control operations of the flow source and the associated operating parameters of the gases. The control system can, for example in some examples that use a blower as a flow source, determine an amount of power delivered to the blower. The fan or motor speed may depend on the amount of power.

In an example, the flow source 2224 can include a fan and a motor. As shown in Figure 4, the gases source may comprise a first inlet 2222 and a second inlet 2223. The first inlet 2222 may be configured to provide ambient air into the flow generator 2224, and the second inlet 2223 may be configured to be connected to a dry gas source, for example, a gas canister or tank, and to provide said gases into the flow generator 2224. The second inlet 2223 may draw or provide concentrated oxygen into the flow generator 2224. The amount of gases provided or drawn by the first inlet 2222 and/or the second inlet 2223 may be controlled by one or more valves (not shown). For example, the first inlet 2222 may be controlled by a first valve, and the second inlet 2223 may be controlled by a second valve. The one or more valves may be controlled by the controller 2226. The oxygen concentration level, which may also be referred to as the concentration of oxygen in the gases may be defined by the ratio of ambient air provided or drawn by the first inlet 2222 to the oxygen provided or drawn by the second inlet 2223. The oxygen concentration level may be controlled by controlling the first valve and/or the second valve. In an example, the oxygen concentration level may be controlled by controlling only the second valve.

2.1 Control System

Figure 5 illustrates a block diagram of an example of a control system 2320 that can detect patient conditions and control operation of the respiratory assistance system 10, 2200 including the gas source or respiratory apparatus 60, 2202. In an example, the control system 2320 controls the operating flow rate 2332 of the gas flowing through the respiratory assistance system 10, 2200 as it is delivered to a patient.

The control system 2320 can increase or decrease the flow rate by controlling a motor speed of the blower and/or a valve in a blender. The control system 2320 can automatically control the operating flow rate for a particular patient based on a first parameter indicative of the patient’s respiratory rate and a second parameter indicative of the patient’ s heart rate, as discussed below. The flow rate can be optimized by the control system 2320 to improve patient comfort and therapy.

Additionally, or alternatively, the control system 2320 can also increase or decrease the oxygen concentration level by controlling the f ' . . . ’de gases from the first and second inlets respectively. The control system 2320 can automatically control the operating oxygen concentration level for a particular patient. The oxygen concentration level can be optimized by the control system 2320 to improve patient comfort and therapy.

The control system 2320 can also generate audio and/or visual outputs 2334. For example, the respiratory assistance system 10, 2200 can include a display which may further include a speaker. The display can indicate to the physicians any warnings or alarms generated by the control system 2320. The display can also indicate control parameters that can be adjusted by the physicians. For example, the control system 2320 can automatically display the operating a flow rate for a particular patient. The control system 2320 can also generate a recovery state of the patient and send it to the display.

In some examples, the control system 2320 can change a temperature set point 2330 of one of the heating elements, such as chamber heater, to control the output conditions of the gas delivered to the patient. The control system 2320 can also change the operation or duty cycle of the heaters described above.

As will be described, the control system 2320 can determine outputs 2330-2334 based on one or more received inputs 2302-2306. The inputs 2302, 2304 can correspond to sensor measurements received automatically by the controller 19, 600, or 2226.

The control system 2320 receives sensor inputs corresponding to patient sensor inputs 2302. Patient sensor inputs may be from one or more wearable sensors configured to be attached to patient to measure or provide an indication of one or more patient parameters. The patient parameter may be SpO2 or respiratory rate or heart rate or a combination thereof, as will be discussed. The (wearable) sensors may include a respiratory rate sensor and a heart rate sensor.

The control system may also receive sensor inputs from device sensors 2304. For example, such device sensors may comprise one or more: pressure sensor(s), flow rate sensor(s), temperature sensor(s), oxygen concentration sensor(s), or ambient sensor(s) in the respiratory assistance system 10, 2200 described above.

The control system 2320 may also receive inputs from user 2306 or stored values in a memory. For example, the user may input one or more initial values for one or more of the operating parameters, and/or values defining a range for one or more of the operating parameters. In an example, the initial operating flow rate and/or initial operating oxygen concentration level may be manually set by a clinician. In an example, a range for the operating flow rate and/or the operating oxygen concentration level may also be manually set by a clinician. Alternatively, the initial and/or range for the operating flow rate and/or the operating oxygen concentration level could be pre-set or stored in a memory.

In a further example, the initial and/or range for the operating flow rate and/or the operating oxygen concentration level may be automatically determined based on one or more additional parameters. The one or more additional parameters may be inputted by the user and/or stored in memory. The one or more additional parameters may correspond to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, weight, sex, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the initial and/or range for the operating flow rate and/or the operating oxygen concentration level.

The control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy. The control system 2320 may also dynamically adjust the operating oxygen concentration level 2336 for a patient prior to and/or during their therapy, e,g. to restore the patient’s SpO2 to optimal levels. The control system 2320 can continuously detect system parameters and patient parameters.

2.1.1 Controller

The control system 2320 can include programming instructions for detection of input conditions and control of output conditions. The programming instructions can be stored in a memory of the controller 19, 600, or 2226. In some examples, the programming instructions correspond to the methods, processes and functions described herein. The control system 2320 can be executed by one or more hardware processors of the controller 19, 600, or 2226. The programming instructions can be implemented in C, C++, JAVA, or any other suitable programming languages. In some examples, some or all of the portions of the control system 2320 can be implemented in application specific circuitry such as ASICs and FPGAs. As illustrated in Figure 5, the control system 2320 can receive inputs from multiple components of the respiratory assistance system 10, 2200. Not all of the inputs 2302-2306 shown in Figure 5 may be present. The inputs 2302 to 2306 and the outputs 2330 to 2336 may not necessarily be present in all examples. For example, the control system 2320 may only receive the patient sensor input(s) 2302 and generate a flow control output(s) 2332. Depending on the configuration, some of the components corresponding to the inputs may not be included in the respiratory assistance system 10, 2200. Lack of a certain input itself may be used by the control system 2320 to determine the input or system conditions.

2.2 Respiratory Rate and Heart Rate

Respiratory rate and/or heart rate can be an important indicator of patient condition. An abnormal respiratory rate and/or heart rate has been shown to be a predictor of respiratory conditions and/or respiratory disease of a patient, and in some circumstances other serious events such as cardiac arrests and escalation to high levels of care. Respiratory rate and/or heart rate can thus provide an indication of deterioration or improvement in patient condition. Respiratory rate and/or heart rate may also be related to work of breathing.

Changes to the respiratory condition of a patient can quickly manifest into changes in respiratory rate and/or heart rate. When a patient’s condition worsens, their minute ventilation is likely to increase. For example, the efficiency of gas exchange in the lungs may decrease with a worsening condition, requiring a higher minute ventilation to maintain normal blood oxygen levels. This increase in minute ventilation is achieved through some combination of quicker breaths and larger tidal volumes. Furthermore, the body tends to favour taking quicker breaths over larger tidal volumes. Similarly, if normal blood oxygen levels are not maintained as a result of decreased efficiency of gas exchange in the lungs, heart rate may increase to circulate blood more quickly. In this way, respiratory rate and/or heart rate responds relatively quickly to a change in the patient’s condition when compared with other measurable patient parameters such as SpO2.

Respiratory rate and/or heart rate may be affected by other factors; for example, increased physical activity is likely to increase respiratory rate and/or heart rate. However, patients receiving respiratory therapy, such as high flow therapy, are generally stationary and at rest, minimising other potential causes of respiratory rate and/or heart rate changes.

2.2.1 Respiratory Rate Sensors and Heart Rate Sensors Respiratory rate is typically measured manually by counting breaths over a set period of time. This allows for a high possibility of errors as well as an inability to continuously monitor the patient. Manual measurement is thus not suited for the present use.

The present system and method for controlling the flow rate of gas delivered to a patient comprises receiving or determining a first patient parameter indicative of the patient’s respiratory rate and a second patient parameter indicative of the patient’s heart rate based on data from one or more sensors. The one or more sensors, such as sensors 2215, 2217 shown in Figure 4, may be one or more sensors configured to be attached to or located near to a patient to measure patient parameters indicative of the patient’s respiratory rate and heart rate. In an example, one or more of the sensors may be a body mounted respiratory rate and/or heart rate sensor. In these examples, the sensor may be attached to the clothing of the patient. In some examples, one or more of the sensors may be a wearable respiratory rate and/or heart rate sensor configured to be worn by the patient, on their body and/or clothing, such as the wearable sensor is in contact with, or is in close proximity to the patient.

In one example, one or more body-contacting sensors may measure the movement of the diaphragm to determine respiratory rate and/or heart rate. In one example, light transmittancetype and/or reflectance-type sensors are able to measure respiratory rate and/or heart rate by measuring pulsations in venous and/or arterial blood. For example, pulse oximeters may be used to find respiratory rate and/or heart rate. In one example, acoustic sensors may be placed on or near the patient to measure respiratory rate and/or heart rate sonically or through vibrations in the trachea. In one example, a CO2 sensor located near the patient’s mouth and/or nose (for example, attached to a cannula) can determine respiratory rate and/or heart rate through the periodic increase of CO2 concentrations as the patient breathes out.

In some examples, one or more of the wearable respiratory rate and/or heart rate sensors may be mechanical sensors. In some examples, the mechanical sensor(s) may be piezoelectric sensor(s). The piezoelectric sensor may comprise one or more piezoelectric elements. The piezo electric elements may be mounted on the chest or near the diaphragm of the patient. The movement of the patient’s chest during respiration causes the piezo electric elements to move and generate a voltage in light of the movement signal. In some examples, the voltage values may be transmitted to the respiratory therapy device for processing. The respiratory therapy device may determine the respiratory rate and/or heart rate of the patient based on the voltage values. In other examples, the piezoelectric sensor(s) may comprise a processor that processes the voltage values and determines the respiratory rate and/or heart rate. The determined respiratory rate and/or heart rate can then be sent to the respiratory therapy device.

In one example, one or more of the sensors may not be wearable sensors. In these examples, one or more of the sensors may not contact the patient directly. Such sensors may be referred to as non-patient contacting sensors. In one such an example, a piezoelectric sensor may be placed under the mattress of a patient that detects movement that occurs as the patient breathes or as the patient’s heart beats (ballistocardiography) to determine respiratory rate and/or heart rate. In another example, an acoustic based sensor may be used, utilising one or more microphones to detect audio waves relating to the respiratory function of the patient. In other examples, a radar-based sensor configured to measure a patient’s respiratory rate and/or heart rate may be used. The radar-based sensor may measure or detect displacement patterns of the patient which can be used to characterise various cardiopulmonary functions including respiratory rate and/or heart rate.

Other examples of measuring parameters indicative of a patient’ s respiratory rate and heart rate are also envisaged, such as via wearable sensors such as a smart watch.

Alternatively, or additionally to sensors attached to or located near to a patient to measure a patient parameter, analysis of flow and pressure delivered by the NHF therapy device can be used to determine respiratory rate. For example, the controller may use signals from one or more pressure sensors and/or one or more flow sensors of the device. The one or more pressure sensors and/or one or more flow sensors may be located in the flow path of the respiratory system. The patient’s breathing during the provision of therapy may cause changes or fluctuations in the gases in the flow path of the respiratory system. These changes or fluctuations can be measured or determined based on the signals from one or more pressure sensors and/or one or more flow sensors of the device. The changes or fluctuations may then be evaluated (e.g. through fourier transforms or other waveform analysis) to determine or estimate the respiratory rate of the patient.

Any one or more of the above-mentioned sensors and methods for measuring or determining respiratory rate and/or heart rate may be utilised in the present system and method. These methods of measuring a patient’s respiratory rate and/or heart rate are generally non-invasive and unobtrusive, and thus may offer good patient compliance with the monitoring equipment. They can provide continuous and accurate measurement of respiratory rate and/or heart rate.

In some examples, one or more of the sensors may be a dedicated, body-contacting respiratory rate and/or heart rate sensor such as one that uses any of the methods describe above. A dedicated, body-contacting respiratory rate and/or heart rate sensor may provide accurate and non-invasive measurements of the patient’s respiratory rate and/or heart rate. For example, some patients may be somewhat active during therapy, such as when they are moving around or sitting down. In these cases, a wearable sensor that attaches to the body or clothing of the patient would be more convenient.

In other examples, a patient may not be active, and a non-contact sensor may be utilised. For example, a patient may be reclined on a bed while receiving therapy, and as such does not move as much. In such examples, a non-contact stationary sensor such as under-mattress piezoelectric sensor could be used.

The one or more sensors may communicate directly with the controller of the high flow therapy device through a wireless transmitter on the sensor using any suitable wireless communication protocol (such as, for example, near field communication, WiFi or Bluetooth®). Alternatively, one or more of the sensors may communicate through a wired connection. One or more of the sensors may also connect to an intermediate connector, such as a cloud-based connector. The cloud-based connector may then connect with the controller of the high flow therapy device. Alternatively, the cloud-based connector may provide respiratory rate and/or heart rate data to a clinician, who then performs the settings adjustment on the high flow therapy device.

The one or more sensors may be configured to measure or provide data indicative of an instantaneous respiratory rate and/or heart rate of the patient. The one or more sensors may be configured to measure or provide data indicative of an instantaneous respiratory rate and/or heart rate at specific time intervals. The time intervals may be a fixed time interval. In some examples, the fixed time interval is a pre-set time interval. In such examples, the pre-set time interval may be between about 1 minute to about 8 hours. The pre-set time interval may be for example 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes, or 45 minutes, or 1 hour, or 1 hour and 30 minutes, or 2 hours, or 3 hours, or 4 hours, or 5 hours, or 6 hours. In another example, the time interval is a variable time interval. The variable time interval may be based on the respiratory rate and/or heart rate of the patient, and/or the status of the respiratory rate and/or heart rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session.

Alternatively, or additionally, the one or more sensors may be able to measure or provide data relating to patient parameters indicative of a time-averaged measurement of the patient’s respiratory rate and/or heart rate. The time-averaged measurement may be used to achieve a steady state reading of respiratory rate and/or heart rate. The steady state reading of respiratory rate and/or heart rate may ignore any transient measurements. The time-averaged measurement may be calculated over a measurement period. In one example, the measurement period is a fixed measurement period. In some examples, the fixed measurement period is a pre-set measurement period. In such examples, the pre-set measurement period may be between about 5 seconds to about 30 minutes. The pre-set measurement period may be between about 10 seconds to about 15 minutes. The pre-set measurement period may be between about 30 seconds to about 5 minutes. The pre-set measurement period may be for example 30 seconds, or, or 1 minute, or 2 minutes, or 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes. In another example, the measurement period is a variable measurement period. The variable measurement period may be based on the respiratory rate and/or heart rate of the patient, and/or the status of the respiratory rate and/or heart rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session.

In some examples, one or more of the sensors may measure and store a plurality of instantaneous measurements indicative of the patient’s respiratory rate and/or heart rate over the measurement period. In such embodiments the sensor may calculate the time-averaged measurement based on the plurality of instantaneous measurements. The sensor may then then send the calculated time-averaged measurement to the controller of the respiratory therapy device, as discussed above.

Alternatively, the sensor may send instantaneous measurements to the controller of the respiratory therapy device during the measurement period. In such examples, the controller of the respiratory therapy device then calculates the time-averaged measurement. The controller of the respiratory therapy device may then use the time-averaged measurement to determine the status of the patient’s respiratory rate and/or heart rate, as will be discussed. Alternatively, the sensor may send instantaneous measurements to an intermediate controller, such as a remote server, during the measurement period. In such embodiments, the intermediate controller may store the instantaneous measurements and calculate the time-averaged measurement. The intermediate controller may then use the time-averaged measurement to determine the status of the patient’s respiratory rate and/or heart rate, or may send the time- averaged measurement to the controller of the respiratory therapy device.

In some examples, the respiratory rate and/or heart rate reading may comprise a rolling average, such that the current reading at any one point comprises the time-averaged respiratory rate and/or heart rate across the most recent measurement period. This rolling average may be calculated by the sensor, the intermediate connector and/or the therapy controller.

In some examples, the one or more sensors may comprise a plurality of sensors. The plurality of sensors may be used simultaneously to provide respiratory rate and/or heart rate readings. For example, the plurality of sensors may comprise a combination of two or more of: one or more wearable sensors, and/or an under-mattress sensor, and/or the flow and/or pressure sensors in the device. In such examples where a plurality of sensors are utilised, each sensor may send measurements to a controller in a form as described above. The controller may then determine an average respiratory rate and/or heart rate across the plurality of sensors, based on the measurements received from two or more of the available sensors. In some examples, the controller uses the measurements from all of the plurality of sensors to provide a more accurate measurement of the patient’s respiratory rate and/or heart rate.

In some examples, the plurality of sensors may provide redundancy in case of failure. For example, if one of the sensors stops working or is unattached from the patient somehow, respiratory rate and/or heart rate information may still be able to be gathered by the other one or more sensor. In some examples, the plurality of sensors may be used for single-fault tolerance. In such examples, the controller may use the measurements from the plurality of sensors to detect for faults in the sensors, such that a sensor which is providing outlying readings is not taken into account for determining the average respiratory rate of the patient.

Heart rate can be measured by any suitable contact or non-contact sensor. The sensor may be wireless or wired. Examples of sensors that can be used are as described above. For example, a light transmittance-type or light reflectance-type sensor such as a pulse oximeter, an acoustic sensor, a mechanical sensor such as a piezoelectric sensor attached to the body of the patient, or underneath a patient’s mattress (e.g., ballistocardiography) can be used.

Even amongst healthy persons, resting/average heart rate can vary considerably. This can be further compounded by various conditions of a patient’s health. Further, heart rate can vary in the short term by large amounts, for example, exercise or stress can temporarily elevate heart rate. Patients receiving therapy are generally in a resting state and are unlikely to be moving in large amounts, however, even small movements may result in noticeable changes. For these reasons, any heart rate monitoring used in therapy control may be required to be continuous and real time, such that trends in a patient’s heart rate can be accurately established and any shortterm fluctuations are suitably ignored. Measurements may be taken and averaged over a long period, such as 1 minute. Furthermore, changes in therapy may take time to result in a change in heart rate. After a change in a therapy parameter, heart rate should only be measured after a time interval, such as, for example, 5, 10 or 15 minutes.

2.2.2 Respiratory Rate (RR) vs Flow Rate

A graphical representation of a non-limiting example of respiratory rate (RR) versus flow rate relationship is shown in Figure 7, while an example set of collected measurements is illustrated in a graph format in Figure 8. The control system 2320 can control the operating flow rate of the gas flow delivered to the patient via the patient interface. The control of the operating flow rate in turn has an effect on the patient’s measured respiratory rate, as shown by the graphs 2500, 2600 of Figures 7 and 8 and discussed below.

When providing respiratory therapy to a patient using the respiratory therapy system 10, 2200, the patient’s respiratory response can vary over different flow rates, as shown by the graphs 2500, 2600 in Figures 7 and 8. High flow therapy may decrease the respiratory rate of the patient relative to unaided respiration. This may be due to an increased resistance to expiration that leads to longer expiration times, as well as improved dead-space clearance of expired gas and the reduction of rebreathing.

In some examples, flow rate is incrementally increased from an initial flow rate, and respiratory rate is measured at each increment. A respiratory rate status is determined, which may be decreasing, stable, or increasing. Flow rate keeps being increased while RR decreases. A sharp drop in RR occurs at some stage as the flow rate is increased. When RR is stable, increases, or decreases only by a small amount, the flow rate stops being incremented. In this way, the flow rate that achieves a RR just after the sharp decrease in the curve below is reached.

At higher flow rates, there may a long and shallow decrease in RR as shown in Figure 7. As the flow (and thus pressure) increases, the lungs expand more, resulting in a higher surface area of the lungs and more efficient 02 and C02 exchange. Thus, RR slowly decreases as flow increases. However, there may be situations where there may a slight increase in RR at higher flow rates as shown in Figure 8 as discussed below.

When the respiratory therapy is not providing any flow of gases to the patient, the flow rate of gases delivered to the patient is 0 1/min. Using graph 2600 as a non-limiting example, at said flow rate of 0 1/min, the patient will have a certain measured respiratory rate Ro, 2604. The patient’s respiratory rate may be measured in breaths per minute (bpm). Testing has shown that over a range of flow rates, the flow rate vs respiratory rate curve 2602 may substantially follow a shape similar to that shown in Figure 8, although the shape shown in Figure 7 may also be possible.

The first portion of this curve 2602 follows a reverse s-shaped curve (or reversed sigmoid curve). After a certain point, shown by 2606, however, further increases in flow rates cease to further decrease respiratory rate. At substantially this point 2606, a minimum respiratory rate RM is reached, at flow rate FM. At even higher flow rates, the respiratory rate may begin to rise. This may be due to the increased effort required to exhale against the high flow rate. In other patients, the patient’s respiratory rate may remain substantially constant at higher flow rates (i.e. at the minimum). In other patients, the patient’s respiratory rate may continue to decrease after reaching RM (see, for example, Figure 7), but may decrease below a threshold, as discussed later. In further patients, the patient’s respiratory rate may increase and decrease after reaching RM, as will be discussed below in relation to Figure 9 and Figure 10.

For some adult patients, the flow rate FM at which the respiratory rate reaches a minimum may be around 45 1/min. This may vary amongst different patients. It may also differ for the same patient at different times, such as when they are healthy compared to when suffering from respiratory distress. Thus, the minimising flow rate cannot be assumed to be the same for all patients.

An alternative example set of collected measurements is illustrated in a graph format in Figure 9 and Figure 10. As with Figure 8, the patient’s respiratory response can vary over different flow rates, as shown by the graph 2800 in Figure 9 and Figure 10. Over a range of flow rates, the flow rate vs respiratory rate curve 2802 substantially follows a shape similar to that shown.

The alternative curve 2802 shown in Figure 9 and Figure 10 starts similarly to that shown in Figure 7 at lower flow rates, with a steeper negative gradient between about 25 and 30 1/min. Then, the curve 2802 shallows out to a ‘minimum’ point as shown by 2806. As shown in Figure 9, at substantially point 2806, a minimum respiratory rate RM is reached, at flow rate FM. AS shown, after the minimum point, shown by 2806, further increases in the flow rate may cause the patient’s respiratory rate to rise and fall, such that it further decreases and/or increases.

As seen in the graph 2800, at a certain flow rate, there is a sharp drop in respiratory rate. This may be caused by good flushing of the airways, improving CO2 clearance and more fresh gas reaching the lungs. This improves efficiency of gas exchange, and less breaths are required.

In alternative examples, a set of measurements may show a curve that does not have a shallow gradient section at low flow rates like that shown in that of Figure 7 to Figure 10. In such alternative examples, the curve may have a steeper negative gradient at lower flow rates. This may indicate that the increasing flow rates are having an effect on reducing the patient’s respiratory rate, even at lower flow rates.

As shown in Figure 10, at least a first respiratory rate Ri of the patient may be determined at a first flow rate Fi. At least a second respiratory rate R2 of the patient may be determined at a second flow rate F2, The gradient, or rate of change of the patient’s respiratory rate between these two flow rates may be calculated. In one example, a difference AR between at least the first respiratory rate Ri and the second respiratory rate R2 might be determined. As will be discussed, the minimum point 2806 may be established based on AR, or the negative gradient between two or more readings of respiratory rate at corresponding flow rates being above a certain threshold. As shown, after the minimum point, shown by 2806, further increases in the flow rate may cause the patient’s respiratory rate to rise and fall, such that it further decreases and/or increases, The further increases and decreases in the patient’s respiratory rate after the minimum point shown by 2806 may be determined to have a gradient or difference AR which is below a certain threshold. The subsequent negative gradients proceeding the minimum 2806 may be below this threshold, and so do not define the minimum flow rate. This curve will vary between patients based on various parameters and conditions, but generally a minimum will occur after a steep initial decrease in respiratory rate. If a point after said first determined minimum, such as that shown by 2806, is determined to have a gradient or difference AR which is above said certain threshold, then a new minimum may be established.

2.2.3 Respiratory Rate Ranges

In some examples, respiratory rate may also preferentially be kept between an upper threshold and a lower threshold, such that a flow rate as close to the optimal flow rate F_m is achieved that still retains RR within the threshold bounds.

A respiratory rate that is within a desirable range may indicate a healthy and/or stable patient. In Figure 8, this range is shown between RT+ and RT-. This range may be, in some examples, between about 12 - 20 breaths per minute (BPM), 12 - 18 BPM, or 12 - 16 BPM. This range is typically defined by a clinician or physician.

This range may be different based on the type of patient, the type of respiratory disease and other conditions. For example, the range may be different based on if the patient is receiving treatment in a hospital or at home. At home, it may be desirable to have an earlier warning that a patient’s condition is worsening or cannot be stabilised by the high flow therapy. As such, the range used at home may be narrower than that used in the hospital.

A healthy patient is likely to have a resting respiratory rate within the desired range. However, a patient suffering from respiratory distress is likely to have a raised respiratory rate. In the example shown in Figure 8, the patient’s respiratory rate Ro at a flow rate of 0 1/min is above the upper threshold RT+. The desirable range is shown by the shaded area in Figure 8, between RT+ and RT-.

2.2.4 Heart Rate (HR) vs Flow Rate When providing NHF therapy, a patient’s cardiac response can also vary over different flow rates, as illustrated in Figure 11 as a non-limiting example. In some situations, nasal high flow may increase the heart rate of a patient. This may occur for a variety of reasons. For example, the high flow therapy can provide an increased resistance to expiration, requiring increased energy usage from respiratory muscles. To compensate for this, muscular oxygen use increases, and so higher blood flows are required to meet the oxygen demand. As the cardiac volume (per beat) remains roughly constant, heart rate must increase in order to raise blood flow.

Testing has shown that this increase in heart rate may not increase linearly with flow rate. Instead, a rapid increase may occur once a flow rate reaches a certain level, as shown in curve 2912. This may occur at around 30-35 1/min, in one example. As such, the heart rate vs flow rate curve may broadly follow the shape shown in Figure 11. The curve 2912 follows an s-shaped curve (or sigmoid curve). At relatively low flow rates, the gradient of the curve 2912 is close to 0. As flow rate increases, there is a rapid increase in heart rate. In other words, there is a section where the curve has a highly positive gradient. At relatively high flow rates, the curve returns to a gradient close to 0.

In some situations, prior to the rapid increase in the heart rate, there may be a minimum point in the heart rate.

For some adult patients, the flow rates at which the heart rate increases sharply is about 30 - 35 LPM. This may vary amongst different patients. It may also differ for the same patient at different times, such as when they are healthy compared to when suffering from respiratory distress. Thus, these flow rates cannot be assumed to be the same for all patients.

Figure 12 shows another example of a heart rate vs flow rate curve 3012 of a patient, with the sharp increase starting at about 30 1/min.

2.2.5 Heart Rate Ranges

In some examples, heart rate may also preferentially be kept between an upper threshold (e.g., HT+) and a lower threshold (e.g., HT ), such that a flow rate as close to the optimal flow rate F_m is achieved that still retains HR within the threshold bounds.

A heart rate that is within a desirable range (e.g., between HT+ and HT ) may indicate a healthy and/or stable patient. This range may ^: - — ¹~" _3n about 40-130 beats per minute, 50-110 beats per minute, or 50-90 beats per minute. This range is typically defined by a clinician or physician.

A healthy patient is likely to have a resting heart rate within the desired range. However, a patient suffering from respiratory distress is likely to have a raised heart rate.

2.2.6 Overlaid Respiratory Rate and Heart Rate Curves

While the respiratory rate curve (see, for example, Figures 7 to 10) and the heart rate curve (see, for example, Figures 11 and 12) have different scales (see the respective y-axes), the curves may be shifted vertically relative to each other to overlay one another.

Figures 13 and 14 show graphical representations of examples of respiratory rate and heart rate versus flow rate relationship, where the respiratory rate curves 3102, 3202 and the heart rate curves 3112, 3212 have been overlaid. Generally, the rapid decrease in respiratory rate occurs at a flow rate slightly lower than the rapid increase in heart rate. This may mean that the flow rate associated with an inflection point (associated with curves 3102, 3202) corresponding to a transition from a rapid decrease in the respiratory rate (or non-stable respiratory rate) to a relatively stable respiratory rate may be lower than the flow rate associated with an inflection point (associated with curves 3112, 3212) corresponding to a transition from a relatively stable heart rate to a rapid increase in the heart rate (or non-stable heart rate).

The respiratory rate information and heart rate information can be used in conjunction by a controller to control the flow rate delivered to a patient receiving high flow therapy.

2.2.7 High Flow Rate Titration - Optimal Flow rate

The techniques disclosed herein use both the respiratory rate and the heart rate to titrate a flow rate. From testing, it is observed that generally there is a flow rate, or range of flow rates, that may be considered a substantially optimal operating flow rate. Referring to the overlaid respiratory rate curve 3302 and heart rate curve 3312 in Figure 15, the optimal flow rate, FM, at substantially point 3306, occurs at a flow rate higher than the sharp decrease in respiratory rate, and lower than the sharp increase in heart rate. This may mean that the optimal flow rate, FM, may be a flow rate after the respiratory rate has undergone a sharp decrease and before the heart rate undergoes a sharp increase.

Additionally or alternatively, there may be a range of flow rates, shown as shaded region 3307 in Figure 15, which may be considered a substantially operational flow rate range.

At the optimal flow rate 3306 (or within the optimal range 3307), work of breathing is considered to be minimised. The airway flushing effects are maximised from the high flow therapy while the additional muscular effort required to exhale against the high flow is minimised, resulting in a minimum work of breathing.

The optimal flow rate will vary for each patient, and will also vary over time based on a patient condition. As such, it is beneficial that the controller is able to titrate to the optimal flow rate for each patient, and maintain the optimal flow rate continuously. This involves determining when the patient condition may be changing and to change the flow accordingly to maintain the optimal flow rate.

In some examples, the optimal flow rate may generally occur between 20 and 50 LPM, or between 25 and 40 LPM, or between 30 and 35 LPM. The optimal flow rate may be higher for a patient when the patient is at a relatively worse condition. The optimal flow rate may be lower for a patient when the patient is at a relatively healthier condition.

To get to the optimal flow rate, the controller may start at an initial flow rate. After an interval, heart rate and respiratory rate measurements may be taken. The flow rate may then be increased by an increment and both respiratory and heart rates measured, after which there is another interval and measurement, and so on at least until the optimal flow rate may be determined. The initial flow rate, flow rate increments and interval times will be discussed further below. At each (new) measurement, the controller may determine a respiratory rate status to be ‘increasing’, ‘decreasing’ or ‘stable’. A stable status may allow for substantially little or no change in the respiratory rate.

Similarly, at each measurement, the controller may determine a heart rate status to be ‘increasing’, ‘decreasing’ or ‘stable’. A stable status may allow for substantially little or no change in the heart rate.

Figure 16 shows a non-limiting example of a graphical representation of a respiratory rate curve 3402 and a heart rate curve 3412 versus flow rate, illustrating what regions of the curves 3402, 3412 may be determined to be increasing, decreasing, or stable, when flow rate is increasing.

The respiratory rate curve 3402 may generally be divided into three regions: a first region 3404 which is a stable region prior to a rapid decrease in the respiratory rate, a second region (or nonstable region) 3406 which is a decreasing region corresponding to the rapid decrease phase, and a third region 3408 which is a stable region after the rapid decrease.

As a non-limiting example, the second region 3406 may be a region defined between a first inflection point of or on curve 3402 where the RR is determined to transition from a stable phase (or stable region) to a decreasing phase (or non-stable region), and a second inflection point of or on curve 3402 where the RR is determined to transition from the decreasing phase (or non-stable region) to another stable phase (or stable region). The first region 3404 may be determined as the region before the first inflection point, while the third region 3408 may be determined as the region after the second inflection point.

The heart rate curve 3412 may generally be divided into three regions: a first region 3414 which is a stable region prior to a rapid increase in the heart rate, a second region (or non-stable region) 3416 which is an increasing region corresponding to the rapid increase phase, and a third region 3418 which is a stable region after the rapid increase.

As a non-limiting example, the second region 3416 may be a region defined between a first inflection point of or on curve 3412 where the HR is determined to transition from a stable phase (or stable region) to an increasing phase (or non-stable region), and a second inflection point of or on curve 3412 where the HR is determined to transition from the increasing phase (or non-stable region) to another stable phase (or stable region). The first region 3414 may be determined as the region before the first inflection point, while the third region 3418 may be determined as the region after the second inflection point.

As can be seen in Figure 16, the optimal flow rate, FM, occurs at a point where both the heart rate and the respiratory rate are stable (i.e., FM intersects curves 3402, 3412 in the stable regions 3408, 3414), after the decreasing section (i.e., region 3406) of RR, and before the increasing section (i.e., region 3416) of HR.

In this way, the controller may incrementally increase the flow rate until there has been a ‘decreasing’ state (or phase or status) of the respiratory rate (i.e., region 3406), and an ‘increasing’ state (or phase or status) of the heart rate (i.e., region 3416). Once these regions are identified, an operating flow rate can be chosen corresponding to FM, the optimal flow rate.

As such, in one example, the controller may increase the flow rate incrementally until an ‘increasing’ status of heart rate (i.e., region 3416) is determined. Provided that a ‘decreasing’ status of RR (i.e., region 3406) has been determined at a lower flow rate, the operating flow rate may then be set at a flow rate where both RR and HR were found to be ‘stable’ (e.g., regions 3408, 3414), at a point substantially equidistant between the flow rate at which RR changed from decreasing to stable, and the flow rate at which HR changed from stable to increasing.

As a non-limiting example, in the graph 3500 of Figure 17 showing respiratory rate curve 3502 and heart rate curve 3512, there is a relatively large optimal flow rate range shown as shaded region 3507. The operating flow rate or the optimal flow rate, FM, may be chosen to be in the middle of this range 3507. Alternatively, the operating flow rate or the optimal flow rate, FM, may be chosen to be at or towards the lower bound of this range 3507, e.g., corresponding to the flow rate at substantially point 3508, where RR changes from a decreasing state (or status) to a stable state (status). Alternatively, the operating flow rate or the optimal flow rate, FM, may be chosen to be at or towards the upper bound of this range 3507.

Alternatively, upon initialisation, the controller may perform a sweep across a predetermined range of flow rates, such as from 20 to 40 LPM at increments of 5 LPM, and determine the RR and HR states (or RR and HR status) at each flow rate increment. Then, the optimal operating flow rate can be determined based on the above criteria. This initial sweep can be done during a warmup mode of the device or before therapy is started. This allows automatic determination of an optimal flow and/or an optimal operational flow range.

2.2.8 Thresholds

There may be a threshold region associated with each of HR and RR, as shown in Figure 18 illustrated with RR curve 3602 and HR curve 3612. The threshold region for RR, shown as shaded region 3603, may be defined between an upper limit RT+ and a lower limit RT-. The threshold region for HR, shown as shaded region 3613, may be defined between an upper limit HT+ and a lower limit HT-. Alternatively, there may be only an upper limit for HR and/or RR (e.g., RT+, HT+), or there may be only a lower limit for HR and/or RR (e.g., RT-, HT ).

The controller may choose a flow rate that keeps RR and HR within the threshold regions 3603, 3613. In the non-limiting example shown in Figure 18, the optimal flow rate, FM, that is determined or chosen, results in RR and HR that are within the thresholds, and, thus, FM is chosen as the operating flow rate.

Referring to the non-limiting example of Figure 19, there may be situations where the optimal flow rate, FM, results in a RR that is within the threshold region 3703 but a HR that is outside the threshold region 3713. In such cases, the controller may choose an operating flow rate that is as close to the optimal flow rate as possible, and that keeps both RR and HR within the thresholds 3703, 3713. In the example of Figure 19, this flow rate may be FT. If no such flow rate is possible, the controller may provide an alarm (e.g., a visual and/or audio alarm). Alternatively, the controller may provide the alarm directly without having to determine an alternative operating flow rate such as FT.

The above may similarly be applicable where the optimal flow rate, FM, results in a HR that is within the threshold region 3713 but a RR that is outside the threshold region 3703.

2.3 Flow Control Method

Figure 6 illustrates a flow chart of an example of a method 2400 for controlling the flow rate of gas delivered to a patient based on a measured respiratory rate and a measured heart rate of a patient. The process or method 2400 can be implemented by any of the systems and apparatus described herein. The process or method 2400 may for example be implemented by the control system 2320.

The process or method 2400 may be performed continually or continuously over a therapy session. In some examples, the therapy session may be a single therapy session defined from a commencement of therapy being provided at a certain flow rate until the end of the therapy being provided at or above a certain flow rate. In some examples, the flow rate defining the commencement and end of therapy may be any flow rate at or above 0 1/min.

The control system 2320 can adjust the operating flow rate of the gases delivered or provided by the respiratory therapy device or apparatus 2202. The control system 2320 follows the iterative process or method 2400 discussed below of titration to find a substantially optimal operating flow rate using feedback from one or more sensors. A substantially optimal operating flow rate may be a flow rate at which a patient’s respiratory rate or heart rate is at or close to a minimum. Additionally, in some examples, a substantially optimal operating flow rate may be a flow rate at which a patient’s respiratory rate and/or heart rate is within a range.

The control system 2320 can, for example, increase the motor speed of the blower when a blower is used as the flow source 2224 to increase the operating flow rate of gases through the respiratory assistance system 10, 2200. The control system 2320 can measure one or more patient conditions in response to changes to one or more system parameters. The control system 2320 can measure the patient’s respiratory rate and heart rate in response to changes to the operating flow rate. a. Initial operating flow rate

The process 2400 can begin at block 2402 with the respiratory therapy device 2202 commencing delivery of a gas flow. The gas flow is provided at at least an operating flow rate. In some examples, the operating flow rate is sufficient to provide high flow therapy to the patient in use, such as within the ranges of flow rates as previously discussed. The control system 2320 may set an initial operating flow rate. The control system may also set other operating parameters of the respiratory therapy device or respiratory apparatus 2202. The operating parameters of the respiratory therapy device 2202 may control the characteristics of the flow of gases delivered or provided by the respiratory therapy device 2202. As described previously, the initial operating flow rate may be manually set by a clinician. In an example, a range for the operating flow rate may also be manually set by a clinician. Alternatively, the initial and/or range for the operating flow rate may be pre-set or stored in a memory. The initial and/or range for the operating flow rate may alternatively be determined based on one or more additional parameters. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like, and/or system parameters including time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the initial and/or range for the operating flow rate.

In some examples, once therapy has commenced, in an optional step (not shown), the operating flow rate may initially be increased by an increment. In such examples, once the operating flow rate has been increased by an increment in this step, the process 2400 then proceeds to start the iterative control loop comprising steps 2404 to 2414. b. Intervals

Once therapy has commenced, and gas flow is provided by the respiratory therapy device at an operating flow rate, the process 2400 then proceeds to start an iterative control loop comprising steps 2404 to 2414. The iterative control loop is performed at intervals, and comprises, at said intervals, performing the steps 2404 to 2414.

In some examples, an interval is defined by the control system 2320 waiting for a time interval before performing each of steps 2404 to 2410/2412. For example, the control system 2320 can wait for a time interval before proceeding to perform the steps of 2404 to 2410/2412. This step is shown by block 2414 of the process 2400. The step 2414 of waiting for an interval may be performed before step 2404, and after step 2410 or 2412 has been performed, such that there is a delay between performing each iteration of the control loop of the process 2400. It will be appreciated that steps 2404 to 2410/2412 may be performed substantially in the same time interval.

In some examples, the time interval may be a fixed time interval. The fixed time interval may be the same interval for each iteration of the control loop. In some examples, the fixed time interval is a pre-set time interval. For example, the pre-set time period can be less than 10 minutes or greater than or equal to 10 minutes. In such examples, the pre-set time interval may be between about 1 minute to about 8 hours. The pre-set time interval may be for example 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes, or 45 minutes, or 1 hour, or 1 hour and 30 minutes, or 2 hours.

In other examples, the time interval is a variable time interval. The variable time interval may be different or have the option of being different between each interval for each iteration of the control loop. The variable time interval may be based on a calculation or determination. In some examples, the variable time interval may be based on the respiratory rate and/or heart rate of the patient, and/or the status of the respiratory rate and/or heart rate of the patient, and/or one or more devices and/or patient sensor readings, and/or the amount of time in the therapy session. In some examples, the variable time period is calculated or determined by the control system 2320 at each interval.

In further examples, the time period is set to a first value when the status of the patient’s respiratory rate is within a first range and/or the status of the heart rate is within a third range, and to at least a second value when the status of the patient’s respiratory rate is within a second range and/or the status of the heart rate is within a fourth range. For example, if the control system 2320 determines that the patient’s respiratory rate is decreasing and/or the heart rate is increasing at a certain rate above a threshold between intervals, the time period may be set to a first value. If the control system 2320 determines that the patient’s respiratory rate is decreasing and/or the heart rate is increasing at a certain rate below a threshold between intervals, the time period may be set to a second value. The first value may be shorter than the second value. In other embodiments, the first value may be greater than the second value. Further thresholds and corresponding values are envisaged. c. Measuring or determining respiratory rate

At block 2404, the control system 2320 receives or determines a first patient parameter indicative of the patient’s respiratory rate. The first patient parameter indicative of the respiratory rate of the patient may be based on data from one or more sensors, as discussed above.

As discussed above, the control system 2320 can determine the patient’s respiratory rate based on one or more received sensor measurements at block 2404. In an example, the sensor measurement is a plethysmographic signal. Other measurements for determining respiratory rate are discussed above. In some examples, the patient’s respiratory rate may be inputted via a user interface and received by the control system 2320. The control system 2320 may store the received or determined respiratory rate in the memory.

In some examples, the control system 2320 may assess the quality of the received data or determined respiratory rate. In such examples, the control system 2320 may determine that additional measurements of respiration rate are required based on the received data or determined respiratory rate being unsuitable. For example, the control system 2320 can determine if the last measured respiration rate is at or exceeded a boundary condition. If the control system 2320 determines that additional measurements are needed, then the control system 2320 can perform step 2404 again until a suitable reading is obtained. In the alternative, if the control system 2320 determines that additional measurements are not required, the control system 2320 can then proceed to determine a status of the patient’s respiratory rate at block 2406, as will be discussed.

The control system 2320 may store the measured first patient parameter indicative of the patient’s respiratory rate for each interval or measurement period in the memory. The control system 2320 can also store additional parameters of patient and/or system in the memory and associate it with the measured first patient parameter for each interval. Accordingly, the control system 2320 can store the state of the patient and the respiratory assistance system 10, 2200 in conjunction with the measured parameter. d. Measuring or determining heart rate

At block 2405, the control system 2320 receives or determines a second patient parameter indicative of the patient’s heart rate. The second patient parameter may be based on data from one or more sensors, as discussed above.

As discussed above, the control system 2320 can determine the patient’s heart rate based on one or more received sensor measurements at block 2405. Measurements for determining heart rate are discussed above. In some examples, the patient’s heart rate may be inputted via a user interface and received by the control system 2320. The control system 2320 may store the received or determined heart rate in the memory. In some examples, the control system 2320 may assess the quality of the received data or determined heart rate. In such examples, the control system 2320 may determine that additional measurements of heart rate are required based on the received data or determined heart rate being unsuitable. For example, the control system 2320 can determine if the last measured heart rate is at or exceeded a boundary condition. If the control system 2320 determines that additional measurements are needed, then the control system 2320 can perform step 2405 again until a suitable reading is obtained. In the alternative, if the control system 2320 determines that additional measurements are not required, the control system 2320 can then proceed to determine a status of the patient’s heart rate at block 2407, as will be discussed.

The control system 2320 may store the measured second patient parameter indicative of the patient’s heart rate for each interval or measurement period in the memory. The control system 2320 can also store additional parameters of patient and/or system in the memory and associate it with the measured second patient parameter for each interval. Accordingly, the control system 2320 can store the state of the patient and the respiratory assistance system 10, 2200 in conjunction with the measured parameter.

It should be appreciated that the steps 2404 and 2405 may be carried out separately in any order, or may be carried out substantially simultaneously.

It should be appreciated that the first patient parameter and the second patient parameter may be based on data from respective sensors or from one/single sensor. e. Determining status of respiratory rate

At block 2406, the control system 2320 determines a first status of the patient’s respiratory rate. The control system 2320 determines a first status of the patient’s respiratory rate based at least on said first patient parameter received or determined at step 2404. The control system 2320 may also determine the first status based on one or more first patient parameters received or determined at one or more previous intervals.

In some examples, the first status is determined based on comparing said received or determined first patient parameter at the present interval, to at least the first patient parameter received or determined at one or more previous intervals. In some examples, the first status is based at least on comparing said received or determined first patient parameter to the first patient parameter received or determined at the most recent previous interval.

In examples such as the above, said comparison may indicate the change of the first patient parameter between two or more intervals.

In some examples, the first status may be determined based on assessing a trend in the patient’s respiratory rate over time. The trend may be based at least on said measured first patient parameter taken at the present interval, and one or more first patient parameters measured at one or more previous intervals. The trend may indicate the change of the first patient parameter between two or more intervals.

In some examples, the step of determining the first status may include calculating by the control system 2320 the rate of the change of the patient’s respiration rate over time. The first status may be determined based on assessing a rate of change of the first patient parameter. The rate of change of the first patient parameter may be determined based on a calculation which uses the first patient parameter received or determined at the present interval, and one or more first patient parameters received or determined at one or more previous intervals. The control system 2320 may determine a derivative of a function using the one or more first patient parameters in the function.

In some examples, the first status may be a state of a patient’s respiratory rate. The state of the patient’s respiratory rate may be for example grouped into a category. In some examples, the category may be such as ‘stable’ or ‘reducing’ (or ‘decreasing’) or ‘increasing’.

The state of the patient’s respiratory rate may be for example grouped into a category based on the comparison of the first patient parameter at different intervals, and/or the calculated rate of change of the patient’s respiratory rate.

For example, if based on the comparison or determination or calculation discussed above between said received or determined first patient parameter at the present interval with at least the first patient parameter received or determined at one or more previous intervals the control system determines that the patient’s respiratory rate has decreased between intervals, the status of the patient’s respiratory rate may be indicated as ‘reducing’ or ‘decreasing’.

Additionally, if the comparison or determination or calculation indicates that the patient’s respiratory rate has increased between intervals, the first status of the patient’s respiratory rate may be indicated as ‘increasing’.

Additionally, if the comparison or determination or calculation indicates that the patient’s respiratory rate has substantially stayed the same between intervals, the first status may be indicated as ‘stable’. The control system 2320 may indicate that the first status is ‘stable’ if the comparison or determination or calculation indicates that the change in patient’s respiratory rate is below a threshold.

In some examples, the threshold may be quantified as a percentage of difference, or change between said received or determined first patient parameter at the present interval with at least the first patient parameter received or determined at one or more previous intervals. In such examples, the threshold may be percentage of difference, or change of above 2.5%. In further examples, the threshold may be percentage of difference, or change of above 5%. In further examples, the threshold may be percentage of difference, or change of above 7.5%. In further examples, the threshold may be percentage of difference, or change of above 10%. In further examples, the threshold may be percentage of difference, or change of above 12.5%. In further examples, the threshold may be percentage of difference, or change of above 15%. In further examples, the threshold may be percentage of difference, or change of above 20%. In further examples, the threshold may be percentage of difference, or change of above 25%.

In some examples, the threshold may be quantified as an amount of difference, or change between said received or determined first patient parameter at the present interval with at least the first patient parameter received or determined at one or more previous intervals. In such examples, the threshold may be amount of difference, or change of above 0.1 breaths per minute (bpm). In further examples, the threshold may be amount of difference, or change of above 0.5 bpm. In further examples, the threshold may be amount of difference, or change of above 1 bpm. In further examples, the threshold may be amount of difference, or change of above 1.5bpm. In further examples, the threshold may be amount of difference, or change of above 2 bpm. In further examples, the threshold may be amount of difference, or change of above 2.5 bpm. In further examples, the threshold may be amount of difference, or change of above 4 bpm. In further examples, the threshold may be amount of difference, or change of above 5 bpm.

In some examples, the threshold may be automatically determined based on one or more parameters. The one or more parameters may be inputted by the user and/or stored in memory. The one or more parameters may correspond to the patient conditions and/or system conditions. Parameters may include patient characteristics, such as age, weight, sex, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system can use these parameters in determination of the threshold.

The control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy. The control system 2320 may also dynamically adjust the operating oxygen concentration level 2336 for a patient prior to and/or during their therapy. The control system 2320 can continuously detect system parameters and patient parameters (including first patient parameter).

As shown in Figure 10, at at least a first interval, relating to flow rate Fi, one or more first patient parameters, shown by Ri, are received or determined. At at least a second interval, occurring after said first interval, said second interval relating to flow rate F2, one or more first patient parameters, shown by R2, are received or determined.

The first status may be determined based on at least Ri and R2. In an example, the gradient, or rate of change of the patient’s respiratory rate between at least these two flow rates, Fi and F2, may be calculated. In one example, a difference AR between at least the first respiratory rate Ri and the second respiratory rate R2 may be determined. As discussed, the first status may be based on AR, or the negative gradient between two or more readings of respiratory rate at corresponding flow rates, and intervals. Additionally, the first status may be based on AR in comparison to a threshold. The threshold may be such as discussed above.

In some examples, the control system may determine if the patient’s respiratory rate has reached a minimum respiratory rate. For example, as shown in Figure 7 and Figure 8, the minimum respiratory rate RM of the patient can be reached at flow rate FM. In such examples, the first status may be categorised as ‘stable’ when it is determined that the patient’s respiratory rate has reached a minimum respiratory rate, based on the methodology as discussed above.

Additionally, or alternatively, the first status may be categorised by a degree of change based on the comparison or determination or calculation performed between the data from different intervals. In such examples, the first status may indicate the degree or amount of change at each interval. For example, the first status may indicate the patient’s respiratory rate is decreasing, and the degree or amount of change at the present interval is a certain amount (for example, as quantified in breaths per minute (bpm)) when compared to the previous interval. For example, this may be in relation to a threshold which may be quantified as an amount or a percentage of difference or change, as previously discussed.

The determination of the first status may take into account the determined first status at one or more previous intervals. As such, the control system 2320 may track the first status across or between multiple intervals.

In some examples, the determination of the first status may take into account the determined first status since the provision of therapy began. For example this may be from the provision of therapy at the initial operating flow rate. The control system may determine that the operating flow rate be adjusted or increased until the control system determines that the first status indicates that the patient’s respiratory rate is decreasing, before it then makes a determination to subsequently maintain the flow rate. In other words, the control system adjusts the operating flow rate from the initial operating flow rate until the patient’s respiratory rate or the first status changes above or outside of a threshold. After that point, the control system continues to adjust the flow rate, until the control system determines that the patient’s respiratory rate or the first status is below or within said threshold, or a different threshold. At that point, the control system maintains the operating flow rate.

For example, in relation to the graphs shown in Figure 7 to Figure 10, as shown by the curve, the patient’s respiratory rate is relatively stable at lower flow rates, with a steeper negative gradient between about 25 and 30 1/min. Then, the curve shallows out to a ‘minimum’ point. A minimum respiratory rate RM is reached, at flow rate FM. In this example, the control system adjusts the operating flow rate from the initial operating flow rate throughout said lower flow rate values where the patient’s respiratory rate is substantially stable, until the patient’s respiratory rate or the first status changes above or outside of a threshold, which corresponds to the steeper negative gradient of the curve. After that point, the control system continues to adjust the flow rate, until the control system determines that the patient’s respiratory rate or the first status is below or within said threshold, or a different threshold. This would be considered to be the point at which the curve shallows out to the ‘minimum’ point, indicated by the minimum respiratory rate RM, at flow rate FM. At that point, the control system maintains the operating flow rate. The control system then continues to determine the first status, and will determine that the operating flow rate be adjusted should the first status indicate that it should be, for example, if the rate of change of the patient’s respiratory rate is outside a threshold. f. Determining status of heart rate

At block 2407, the control system 2320 determines a second status of the patient’s heart rate. The control system 2320 determines a second status of the patient’s heart rate based at least on said second patient parameter received or determined at step 2405. The control system 2320 may also determine the second status based on one or more second patient parameters received or determined at one or more previous intervals.

In some examples, the second status is determined based on comparing said received or determined second patient parameter at the present interval, to at least the second patient parameter received or determined at one or more previous intervals.

In some examples, the second status is based at least on comparing said received or determined second patient parameter to the second patient parameter received or determined at the most recent previous interval.

In examples such as the above, said comparison may indicate the change of the second patient parameter between two or more intervals.

In some examples, the second status may be determined based on assessing a trend in the patient’s heart rate over time. The trend may be based at least on said measured second patient parameter taken at the present interval, and one or more second patient parameters measured at one or more previous intervals. The trend may indicate the change of the second patient parameter between two or more intervals. In some examples, the step of determining the second status may include calculating by the control system 2320 the rate of the change of the patient’s heart rate over time. The second status may be determined based on assessing a rate of change of the second patient parameter. The rate of change of the second patient parameter may be determined based on a calculation which uses the second patient parameter received or determined at the present interval, and one or more second patient parameters received or determined at one or more previous intervals. The control system 2320 may determine a derivative of a function using the one or more second patient parameters in the function.

In some examples, the second status may be a state of a patient’s heart rate. The state of the patient’ s heart rate may be for example grouped into a category. In some examples, the category may be such as ‘stable’ or ‘reducing’ (or ‘decreasing’) or ‘increasing’.

The state of the patient’s heart rate may be for example grouped into a category based on the comparison of the second patient parameter at different intervals, and/or the calculated rate of change of the patient’s heart rate.

For example, if based on the comparison or determination or calculation discussed above between said received or determined second patient parameter at the present interval with at least the second patient parameter received or determined at one or more previous intervals the control system determines that the patient’ s heart rate has increased between intervals, the status of the patient’s heart rate may be indicated as ‘increasing’.

Additionally, if the comparison or determination or calculation indicates that the patient’s heart rate has decreased between intervals, the second status may be indicated as ‘decreasing’.

Additionally, if the comparison or determination or calculation indicates that the patient’s heart rate has substantially stayed the same between intervals, the second status may be indicated as ‘stable’. The control system 2320 may indicate that the second status is ‘stable’ if the comparison or determination or calculation indicates that the change in patient’s heart rate is below a threshold.

In some examples, the threshold may be quantified as a percentage of difference, or change between said received or determined second patient parameter at the present interval with at least the second patient parameter received or determined at one or more previous intervals. In such examples, the threshold may be percentage of difference, or change of above 2.5%. In further examples, the threshold may be percentage of difference, or change of above 5%. In further examples, the threshold may be percentage of difference, or change of above 7.5%. In further examples, the threshold may be percentage of difference, or change of above 10%. In further examples, the threshold may be percentage of difference, or change of above 12.5%. In further examples, the threshold may be percentage of difference, or change of above 15%. In further examples, the threshold may be percentage of difference, or change of above 20%. In further examples, the threshold may be percentage of difference, or change of above 25%.

In some examples, the threshold may be quantified as an amount of difference, or change between said received or determined second patient parameter at the present interval with at least the second patient parameter received or determined at one or more previous intervals. In such examples, the threshold may be amount of difference, or change of above 1 beat per minute. In further examples, the threshold may be amount of difference, or change of above 2 beats per minute. In further examples, the threshold may be amount of difference, or change of above 5 beats per minute. In further examples, the threshold may be amount of difference, or change of above 10 beats per minute. In further examples, the threshold may be amount of difference, or change of above 20 beats per minute.

In some examples, the threshold may be automatically determined based on one or more parameters. The one or more parameters may be inputted by the user and/or stored in memory. The one or more parameters may correspond to the patient conditions and/or system conditions. Parameters may include patient characteristics, such as age, weight, sex, height, sleep state (awake or asleep), respiratory symptoms (e.g., presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system can use these parameters in determination of the threshold.

The control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy. The control system 2320 may also dynamically adjust the operating oxygen concentration level 2336 for a patient prior to and/or during their therapy. The control system 2320 can continuously detect system parameters and patient parameters (including second patient parameter). As shown in Figure 11, at at least a first interval, relating to flow rate F3, one or more second patient parameters, shown by Hi, are received or determined. At at least a second interval, occurring after said first interval, said second interval relating to flow rate F4, one or more second patient parameters, shown by H2, are received or determined.

The second status may be determined based on at least Hi and H2. In an example, the gradient, or rate of change of the patient’s heart rate between at least these two flow rates, F3 and F4, may be calculated. In one example, a difference AH between at least the first heart rate Hi and the second heart rate H2 may be determined. As discussed, the second status may be based on AH, or the positive gradient between two or more readings of heart rate at corresponding flow rates, and intervals. Additionally, the second status may be based on AH in comparison to a threshold. The threshold may be such as discussed above.

In some examples, the control system may determine if the patient’s heart rate is at a minimum before the heart rate increases. In such examples, the second status may be categorised as ‘stable’ for flow rates prior to the flow rate when it is determined that the patient’s heart rate has reached a minimum heart rate, based on the methodology as discussed above.

Additionally, or alternatively, the second status may be categorised by a degree of change based on the comparison or determination or calculation performed between the data from different intervals. In such examples, the second status may indicate the degree or amount of change at each interval. For example, the second status may indicate the patient’s heart rate is increasing, and the degree or amount of change at the present interval is a certain amount (for example, as quantified in beats per minute) when compared to the previous interval. For example, this may be in relation to a threshold which may be quantified as an amount or a percentage of difference or change, as previously discussed.

The determination of the second status may take into account the determined second status at one or more previous intervals. As such, the control system 2320 may track the second status across or between multiple intervals.

In some examples, the determination of the second status may take into account the determined second status since the provision of therapy began. For example, this may be from the provision of therapy at the initial operating flow rate. The control system may determine that the operating flow rate be adjusted or increased until the control system determines that the second status indicates that the patient’s heart rate is increasing, before it then makes a determination to subsequently maintain the flow rate. In other words, the control system adjusts the operating flow rate from the initial operating flow rate, while the patient’s heart rate or the second status is determined by the control system to be below or within a threshold, until the patient’s heart rate or the second status changes above or outside of the threshold, or a different threshold. At that point, the control system maintains the operating flow rate.

For example, in relation to the graphs shown in Figures 11 and 12, as shown by the curve, the patient’s heart rate is relatively stable at lower flow rates, with a steeper positive gradient between about 30 and 35 1/min. Then, the curve becomes relatively stable at higher flow rates. In this example, the control system adjusts the operating flow rate from the initial operating flow rate throughout said lower flow rate values where the patient’s heart rate is substantially stable (e.g., where the heart rate may be minimum), until the patient’s heart rate or the second status changes above or outside of a threshold, which corresponds to the steeper positive gradient of the curve. At that point, the control system maintains the operating flow rate at the present flow rate or a flow rate where the heart rate was relatively stable. The control system may continue to determine the second status.

It should be appreciated that the steps 2406 and 2407 may be carried out separately in any order, or may be carried out substantially simultaneously.

Further, it should be appreciated that a particular patient parameter and the corresponding status may be determined first before another patient parameter is determined. For example, steps 2404 and 2406 for the first patient parameter and the first status may first be carried out before commencing step 2405 for the second patient parameter, or vice versa. g. Calibrations

Over time, a patient’s condition may change. For example, their condition may improve or deteriorate, resulting in different biochemistry that means the level of respiratory support required to minimise work of breathing is different. As such, the substantially optimal operating flow rate may change as a result of a patient’s changing condition. The controller may regularly perform a ‘calibration’ that determines if the current operating flow rate is still the substantially optimal operating flow rate or if the current operating flow rate remains suitable for the patient’ s prevailing condition.

The controller may perform the calibration at a regular interval or defined time interval, for example, between 30 minutes and 3 hours, between 1 hour and 2 hours, or preferably every 1 hour.

To perform the calibration, the controller may take respiratory rate and heart rate measurements at the operating flow rate, at a (first) flow rate an increment above the operating flow rate (i.e., an upper flow rate), and at a (second) flow rate an increment below the operating flow rate (i.e., a lower flow rate).

For example, to perform the calibration, the controller may take a respiratory rate and heart rate measurement at the operating flow rate. Then, the controller may increase the flow rate by an increment, and take another respiratory rate and heart rate measurement after waiting a time interval for the patient to respond to the change in flow rate. Then, the controller may decrease the flow rate to be an increment below the previous operating flow rate (i.e., effectively a two increment decrease in real time), and take another respiratory rate and heart rate measurement after waiting a time interval. Alternatively, the controller may do the lower flow rate first, then the higher flow rate.

Suitable non-limiting examples for the time interval may be 5 minutes, 10 minutes, or 15 minutes.

The increment may be between 2 and 10 L/min, preferably 5 L/min.

The controller may determine a respiratory rate status at the upper and lower flow rates, relative to the respiratory rate at the operating flow rate FM. Similarly, the controller may determine a heart rate status at the upper and lower flow rates, relative to the heart rate at the operating flow rate FM.

Using the method 2400 as a non-limiting example, steps 2404 to 2407 to determine the first status and the second status may comprise the controller, at each interval and/or at a defined time interval, determining or receiving a first patient parameter and a second patient parameter at the present (or maintained) operating flow rate, at a first flow rate above the operating flow rate (e.g., by an increment), and at a second flow rate below the operating flow rate (e.g., by an increment). The controller may then use the first patient parameter and the second patient parameter at the present operating flow rate (i.e., the present respiratory rate and heart rate), the first patient parameter and the second patient parameter at the first flow rate (i.e., the higher flow respiratory and heart rates), and the first patient parameter and the second patient parameter at the second flow rate (i.e., the lower flow respiratory and heart rates) to determine the first and second status at these different flow rates. The respective first and second status at these different flow rates may be compared relative to one another.

In these examples, step 2404 of method 2400 comprises the controller, in any order, determining or receiving the first patient parameter at the present operating flow rate; increasing the operating flow rate by an increment above the present operating flow rate, and determining or receiving the first patient parameter at the increased operating flow rate; decreasing the flow rate to be an increment below the present operating flow rate, and determining or receiving the first patient parameter at the decreased operating flow rate. In some examples, further first patient parameters are determined or received at one or more additional increments above and/or below the operating flow rate.

Similarly, in these examples, step 2405 of method 2400 comprises the controller, in any order, determining or receiving the second patient parameter at the present operating flow rate; increasing the operating flow rate by an increment above the present operating flow rate, and determining or receiving the second patient parameter at the increased operating flow rate; decreasing the flow rate to be an increment below the present operating flow rate, and determining or receiving the second patient parameter at the decreased operating flow rate. In some examples, further second patient parameters are determined or received at one or more additional increments above and/or below the operating flow rate.

In some examples, determination or receiving of the first and second patient parameters at one or each of the present, decreased, and/or increased operating flow rates comprise waiting for a time interval for the patient to respond to the change in flow rate before determining or receiving of the first and second patient parameters. The time interval and flow increment may be as described herein. In these examples, step 2406 of method 2400 comprises determining the first status based on assessment of the first patient parameters taken at the present operating flow rate (i.e., the present respiratory rate), at the one or more increments above the operating flow rate (i.e., the higher flow respiratory rate(s)), and at the one or more increments below the operating flow rate (i.e., the lower flow respiratory rate(s)). Similarly, step 2407 of method 2400 comprises determining the second status based on assessment of the second patient parameters taken at the present operating flow rate, at the one or more increments above the operating flow rate, and at the one or more increments below the operating flow rate.

The controller is configured to assess the higher flow respiratory rate(s) and higher flow heart rate(s) and determine whether the higher flow respiratory rate(s) and higher flow heart rate(s) indicate the patient’s respiratory rate is stable or increasing and/or the patient’s heart rate is stable using the methods described herein in relation to steps 2406 and 2407. The controller similarly assesses the lower flow respiratory rate(s) and lower flow heart rate(s) and determines whether the lower flow respiratory rate(s) and lower flow heart rate(s) indicate the patient’s respiratory rate is stable or increasing and/or the patient’s heart rate is stable using the methods described herein in relation to steps 2406 and 2407.

As such, the controller may be configured to assess the first status and the second status at the operating flow rate, at one or more increments above the operating flow rate, and at one or more increments below the operating flow rate. Based on the assessment, the controller may determine the patient’s respiratory rate and/or heart rate at the operating flow rate is stable, is increasing, or is decreasing; and similarly at the one or more increments above the operating flow rate is stable, is increasing, or is decreasing; and at the one or more increments below the operating flow rate is stable, is increasing, or is decreasing.

Referring to Figure 20, the controller may determine, in situations where at the one or more increments above the operating flow rate, the respiratory rate (see curve 3902) is stable and the heart rate (see curve 3912) is increasing, and also where at the one or more increments below the operating flow rate, the respiratory rate is increasing and the heart rate is stable, that the present operating flow rate is the optimal operating flow rate. In these situations, the controller may determine, at step 2408, that no change to the operating flow rate is required. Referring to Figure 21, the controller may determine, in situations where at the one or more increments above the operating flow rate, the respiratory rate (see curve 4002) is decreasing and the heart rate (see curve 4012) is stable, and also where at the one or more increments below the operating flow rate, the respiratory rate is increasing and the heart rate is stable, that the operating flow rate is lower than the optimal operating flow rate. In these situations, the controller may determine, at step 2408, that the operating flow rate should be increased by an increment.

The controller may determine, in situations where at the one or more increments above the operating flow rate, the respiratory rate is stable and the heart rate is increasing, and also where at the one or more increments below the operating flow rate, the respiratory rate is stable and the heart rate is decreasing, that the operating flow rate is higher than the optimal operating flow rate. In these situations, the controller may determine, at step 2408, that the operating flow rate should be decreased by an increment.

If the first status and/or the second status at the one or more increments above the operating flow rate and the one or more increments below the operating flow rate do not provide a conclusive determination on if the operating flow rate is the optimal operating flow rate, the controller may perform a second calibration using a second increment.

For example, there may be situations where both respiratory and heart rates may be stable at both upper and lower flow rates. This may indicate that the flow rate is still at the optimal flow rate, and that the upper and lower flow rates are also within the optimal range. However, it may also indicate the operating flow rate is far above the optimal, or far below the optimal, as these regions are also associated with stable respiratory and heart rates. As such, to determine which situation it is, the controller may then perform a second calibration using a second increment.

In some examples, the second increment may be greater than the first increment (or previous increment). The second increment may provide larger changes in the patient’s respiratory and heart rates that can assist in determining where the optimal operating flow rate is. The method as previously described may be repeated using the second increment. This may involve determining or receiving the first patient parameter and the second patient parameter, and, further, determining the corresponding first status and the second status, at a third flow rate that is higher than the first flow rate, and at a fourth flow rate that is lower than the second flow rate. Further, additionally or alternatively, if the status of the patient’s respiratory and heart rates at the one or more increments above the operating flow rate and the one or more increments below the operating flow rate do not provide a conclusive determination on whether the operating flow rate is the optimal operating flow rate, the controller may perform the whole method 2400 again, starting at the initial flow rate again to determine the optimal operating flow rate.

If the controller determines that the operating flow rate is not at the optimal operating flow rate, the controller may automatically change the operating flow rate by an increment to be closer to the optimal flow rate, e.g., by increasing or reducing the operating flow rate by the increment. Alternatively, the controller may instead suggest the change in flow rate to a clinician, who may approve or decline the change. h. Determining whether to adjust or maintain operating flow rate

At block 2408, the control system 2320 can then determine whether to adjust or maintain the operating flow rate, based on the determined first status of the patient’s respiratory rate and the second status of the patient’s heart rate.

The control system 2320 may use the determined first status and the second status to determine whether to adjust or maintain the operating flow rate. If the first status indicates that the patient’ s respiratory rate is decreasing and the second status indicates that the patient’ s heart rate is stable, then the control system 2320 at step 2408 may determine that the operating flow rate be increased. If the first status indicates that the patient’s respiratory rate is substantially stable and the second status of the patient’s heart rate is substantially stable, then the control system 2320 at step 2408 may determine that the operating flow rate be maintained.

In some examples, if the first status indicates that the patient’s respiratory rate is increasing and/or the second status indicates that the patient’s heart rate is decreasing, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased.

In some examples, the control system 2320 at step 2408 uses the first status, the second status and one or more previous adjustments to the operating flow rate to determine whether to increase or decrease the operating flow rate. For example, if the operating flow rate was increased in the previous interval, and the first status of the present interval indicates that the patient’s respiratory rate is decreasing and/or the second status of the present interval indicates the patient’s heart rate is stable, then the control system 2320 may determine that the operating flow rate be increased.

Conversely, if the operating flow rate was decreased in the previous interval, and the first status indicates that the patient’s respiratory rate is decreasing and/or the second status indicates the heart rate is not relatively stable, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased. Furthermore, if the operating flow rate was decreased in the previous interval, and the first status indicates that the patient’s respiratory rate is increasing and/or the second status indicates the heart rate is relatively stable, then the control system 2320 at step 2408 may determine that the operating flow rate be increased.

In some examples, at block 2408, the control system 2320 may determine that the operating flow rate be maintained based on the first status indicating that the patient’s respiratory rate is substantially the same between intervals and the second status indicating that the patient’s heart rate is substantially the same between the same intervals. The intervals may be the present interval and one or more previous intervals, as discussed above. In such examples, control system 2320 may determine that the patient’s respiratory rate is substantially the same between intervals based on the comparison at step 2406 indicating that the first patient parameter at the present interval is within a defined range or threshold of the one or more previous intervals and that the patient’s heart rate is substantially the same between intervals based on the comparison at step 2407 indicating that the second patient parameter at the present interval is within a defined range or threshold of the one or more previous intervals.

In some examples, at block 2408, the control system 2320 may determine that the operating flow rate be maintained based on the first status and the second status indicating that the patient’s respiratory rate and heart rate are substantially stable, or are otherwise categorised as being ‘stable’. The first status and the second status are determined at respective steps 2406, 2407.

In some examples, at block 2408, based on determining that said operating flow rate be maintained for a first time, the control system 2320 may maintain the operating flow rate by adjusting the operating flow rate back to the operating flow rate of the previous interval. In such examples, the operating flow rate may be set back by the increment to the rate it was at which the minimum or desired respiratory rate and/or heart rate of the patient was achieved. In this way, in one example, the minimum respiratory rate RM can be reached at flow rate FM, as shown in Figure 8. In some examples, the determining that said operating flow rate be maintained for a first time may be a first time in a therapy session. In other examples, it may be the first time across a plurality of therapy sessions.

In these examples, where the patient’s respiratory rate remains substantially constant between intervals, at two operating flow rates, it may be preferable that the lower of the two flow rates is used. In other words, where there is a minimum respiratory rate across multiple flow rates (for example where the curve has a flat portion at the minimum), it is preferable to use the lowest operating flow rate that achieves that minimum respiratory rate.

In some examples, where the patient’s heart rate remains substantially constant between intervals, at two operating flow rates, it may be preferable that the lower of the two flow rates is used. In other words, where there is a minimum heart rate across multiple flow rates (for example where the curve has a flat portion at the minimum), it is preferable to use the lowest operating flow rate that achieves that minimum heart rate.

In other examples, the operating flow rate may not be set back an increment, even when the final increase in operating flow rate causes a slight rise in the patient’s respiratory rate and/or the patient’ s heart rate. As the patient’ s respiratory rate increases at a slower rate with increasing flow rate than decreasing flow rate from the minimum, it may be preferable to have a flow rate set higher than the minimum for added stability.

Increments

If the control system 2320 determines that the operating flow rate be adjusted, it may proceed to step 2410 and adjust the operating flow rate by an increment.

More generally, if the control system 2320 determines that the operating flow rate be adjusted, it may proceed to step 2410 and adjust the operating flow rate by a value or an amount. This may include increasing the operating flow rate by the value or the increment, or decreasing the operating flow rate by the value or the increment. In some examples, the increment may be a fixed time increment. The fixed time increment may be the same increment for each iteration of the control loop. In some examples, the fixed time increment is a pre-set time increment.

In another example, the increment is a variable time increment. The variable increment may be based on the respiratory rate and/or heart rate of the patient, and/or the first status and/or second status, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session. At step 2408 the control system may also determine the size of the variable increment for adjusting the operating flow rate.

In a further example, the increment, whether fixed or variable, may be automatically determined based on one or more additional parameters. The one or more additional parameters may be inputted by the user and/or stored in memory. The one or more additional parameters may correspond to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the increment.

The increment may be between about 0.1 1/min and about 201/min, optionally it may be between about 0.5 1/min and about 15 1/min, optionally it may be between about 1 1/min and about 10 1/min, optionally it may be between about 2 1/min and about 8 1/min, optionally it may be between about 3 1/min and about 6 1/min, preferably it may be about 5 1/min.

In some examples, the process 2400 may use larger flow rate increments at the beginning of a therapy session. This is because the minimum respiratory rate and/or an increase in the heart rate is unlikely to be achieved at low flow rates. For example, increments of 10 1/min may be used up until the system reaches 201/min, or 251/min, or 301/min. After that, 51/min increments may be used. Alternatively, a medical practitioner may set the initial operating flow rate at a higher flow rate such that the titration process is quicker. In the case where the first increment above the initial flow rate yields an increase in respiratory rate, the titration process should begin decreasing the flow rate in increments to find the minimum. In another example, the increments may be proportional to the difference between the respiratory rate received or determined at the present interval and an upper threshold RT+, discussed below. For example, if the patient has a respiratory rate much higher than the upper threshold, then the increments used are larger such that the respiratory rate is brought closer to the desired range at a quicker rate. As this difference becomes smaller, so too do the increments in flow rate used.

Thresholds

In some examples, at block 2408, the control system 2320 can also compare the received or determined patient’s respiratory rate and/or the first status to one or more thresholds, and/or the received or determined patient’s heart rate and/or the second status to one or more thresholds.

In one example, the one or more thresholds corresponding to the respiratory rate and/or the heart rate may be an upper threshold and a lower threshold. The one or more thresholds can be such that the patient’s respiratory rate and the heart rate do not fall outside of respective predetermined ranges. A respiratory rate that is within a desirable range may indicate a healthy and/or stable patient. A heart rate that is within a desirable range may indicate a healthy and/or stable patient.

As an example shown in Figures 8 and 18, the predetermined or desirable range for the respiratory rate is shown between RT+ and RT-. In this example, the upper threshold is RT+ and the lower threshold is RT-. This range may be, in some examples, between about 12 - 20 breaths per minute (BPM), 12 - 18 BPM, or 12 - 16 BPM. This range is typically defined by a clinician or physician. The range may be inputted to the respiratory therapy device and received by the control system 2320. In some examples, the control system 2320 may determine the range based on one or more patient and/or system conditions.

As an example shown in Figure 18, the predetermined or desirable range for the heart rate is shown between HT+ and HT-. In this example, the upper threshold is HT+ and the lower threshold is HT-. This range may be, in some examples, between about 40-130 beats per minute, 50- 110 beats per minute, or 50-90 beats per minute. This range is typically defined by a clinician or physician. The range may be inputted to the respiratory therapy device and received by the control system 2320. In some examples, the control system 2320 may determine the range based on one or more patient and/or system conditions. The ranges may be different based on the type of patient, the type of respiratory disease and other conditions. For example, the ranges may be different based on if the patient is receiving treatment in a hospital or at home. At home, it may be desirable to have an earlier warning that a patient’s condition is worsening or cannot be stabilised by the high flow therapy. As such, the ranges used at home may be narrower than that used in the hospital.

In some embodiments, at block 2408, the control system 2320 can receive additional parameters corresponding to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, sex, weight, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the one or more thresholds.

In some examples, the patient’s curve may be such that the minimum respiratory rate RM is below the lower threshold RT- and/or the minimum heart rate is below the lower threshold HT-. In this case, once respiratory rate drops below RT- and/or the heart rate is below the lower threshold HT-, the control system may change the operating flow rate by an increment such that respiratory rate is at or above RT- and the heart rate is at or above HT-. This ensures that the patient’s respiratory rate is not kept below the lower threshold RT- and the heart rate is not kept below the lower threshold HT-.

In some examples, the control system may decrease the operating flow rate by an increment. The control system may decrease the operating flow rate by an increment when the respiratory rate is below the lower threshold RT-.

In some example, the control system may increase the operating flow rate by an increment. The control system may increase the operating flow rate by an increment when the heart rate is below the lower threshold HT-.

In some examples, the high flow therapy device may reach its maximum operating flow rate before the minimum respiratory rate and/or heart rate is found. In other words, the patient’s minimum respiratory rate and/or heart rate occurs at a flow rate above the maximum operating flow rate achievable by the high flow device. For some devices, the maximum operating flow rate may be 70 - 80 1/min. If the operating flow rate reaches this maximum without achieving the minimum respiratory rate and/or heart rate, an alarm may sound that advises the patient is given a different therapy, for example CPAP, non-invasive ventilation, or invasive ventilation. Alternatively, the high flow therapy device may be capable of delivering different kinds of therapies, such as nasal high flow, CPAP and NIV. In this case, the high flow device may switch to a different type of therapy when the maximum flow rate is reached on the high flow therapy setting.

In another example, the control system 2320 may not seek to achieve the minimum respiratory rate or the minimum heart rate. Instead, the control system may achieve the lowest flow rate at which the respiratory rate and heart rate are within the respective desired ranges, or may determine a flow rate corresponding to a desired respiratory rate and a desired heart rate. For example, the flow rate may be increased to the minimum flow rate at which the heart rate and the respiratory rate are within the respective thresholds. At this point, the control system stops increasing the flow rate.

In another example, it may be desirable to keep the respiratory rate and the heart rate somewhere between the respective upper and lower thresholds. In this embodiment, the control system 2320 would titrate by performing the steps 2404 - 2410/2412 for patient’s respiratory rates and heart rates that are somewhere in the desired ranges. In these examples, the control system 2320 may perform steps 2404 to 2412 so long as the patient’s respiratory rate and the heart rate are within the desired ranges, by comparing the patient’ s respiratory rate and the heart rate to the respective thresholds. In these examples, the control system 2320 may maintain the operating flow rate when the first status and the second status indicate that the patient’s respiratory rate and heart rate are ‘stable’ or at a minimum, such as RM , and the patient’s respiratory rate is additionally within the upper threshold RT+ and the lower threshold RT- and the patient’s heart rate is additionally within the upper threshold HT+ and the lower threshold HT-.

Additionally, or alternatively, the control system 2320 may set boundary or threshold conditions for the operating flow rate and not select a flow rate below a minimum rate. The control system 2320 can also cap flow rate at a maximum rate that may be set by the clinician or stored in the controller. This limit may be based on a flow above which the patient may feel discomfort, for example 120 L/min for adults and 3 L/min/kg for neonatal patients and children. Higher flow rates can also increase noise and pressure. Accordingly, based on the data collected by the control system 2320, it can compare the operating flow rate at the present interval to the boundary or threshold conditions for the flow rate at block 2408. i. Adjusting operating flow rate

At block 2410, the control system 2320 may adjust the operating flow rate based on the control system determining at block 2408 that said operating flow rate be adjusted. The control system 2320 may adjust the operating flow rate by the increment determined at block 2408.

As discussed above, at step 2408, if the first status indicates that the patient’s respiratory rate is decreasing and the second status indicates that the patient’s heart rate is stable, then the control system 2320 may determine that the operating flow rate be increased. At step 2410, the control system 2320 proceeds to increase the operating flow rate by the increment.

In some examples, if the first status indicates that the patient’s respiratory rate is increasing and/or the second status indicates that the patient’s heart rate is increasing, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased.

Increasing the operating flow rate may comprise adjusting the operating flow rate from a first value to a second, higher value. The difference between the first value and the second value is the increment.

The adjustment of the operating flow rate comprises adjusting the motor speed of the flow generator. For example, this may be achieved by outputting one or more flow control outputs 2332, as discussed above. In such examples, increasing the operating flow rate by an increment comprises adjusting the motor speed of the blower from a first value to a second, higher value. The adjustment of the motor speed may be proportional to the adjustment of the operating flow rate.

In some examples, the control system 2320 may adjust the operating flow rate within a range. The range may be defined by a maximum allowable flow rate and/or a minimum allowable flow rate. The control system 2320 may be configured to cease further increases of the operating flow rate should it be determined that a determined increase to the operating flow rate would be above a maximum allowable flow rate. j. Maintaining operating flow rate

At block 2412, the control system 2320 may maintain the operating flow rate based on the control system determining at block 2408 that said operating flow rate be maintained. As discussed above, at step 2408, if the first status indicates that the patient’s respiratory rate is substantially stable, or is otherwise at a minimum, and the second status indicates that the patient’s heart rate is substantially stable, or is otherwise at a minimum, then the control system 2320 may determine that the operating flow rate be maintained. At step 2412, the control system 2320 proceeds to maintain the operating flow rate, as discussed above. k. Waiting for interval

At block 2414, after the control system 2320 either adjusts the operating flow rate at step 2410, or maintains the operating flow rate at step 2412, the process 2400 then proceeds to wait for a time interval before performing each of steps 2404 to 2410/2412 again, as previously discussed.

For example, the control system 2320 can wait for a time interval before proceeding to perform the steps of 2404 to 2410/2412. This step is shown by block 2414 of the process 2400. As such that there is a delay between performing each iteration of the control loop of the process 2400. It will be appreciated that steps 2404 to 2410/2412 may be performed substantially in the same time interval. l. Additional/alternative implementations

In some alternative examples, the control system may be configured to perform steps 2402, 2404 and 2405 initially. The control system may then be configured to display the patient parameter indicative of the patient’s respiratory rate and heart rate to the user via the display of the respiratory therapy apparatus, or a display of an external device in operative communication with the respiratory therapy apparatus and forming a part of the respiratory therapy system. In some examples, alongside the display of the patient parameters indicative of the patient’s respiratory rate and heart rate, an indication of the operative flow rate may also be shown.

Additionally, a user input may be able to be received by the control system. The display may be configured to allow a user interface such as by way of a touchscreen which provides for the user input. In some examples the user input may be provided by one or more buttons, knobs, or dials of the respiratory therapy apparatus. The user input is configured to allow the user to adjust the operating flow rate manually. The adjustment of the operating flow rate performed by the user based on the displayed indication of the patient’s respiratory rate and/or heart rate (or other patient parameter).

In some further examples, the method 2400 may further comprise prompting the user based on the decision at step 2408. In these examples, once step 2408 has determined that the operating flow rate be adjusted, the user is prompted that the operating flow rate is being adjusted via the display. The new operating flow rate, and in some examples the previous operating flow rate, may additionally be presented to the user via the display. As such, the user is informed of the changing of the adjustment to the operating flow rate.

In other examples, once step 2408 has determined that the operating flow rate be adjusted, the user is prompted that the controller has determined that the operating flow rate should be adjusted. In such examples, the user is prompted to confirm whether the adjustment to the operating flow rate should proceed. The user can provide input in response to the prompting, for example via the display. Once a confirmatory input has been received from the user, the controller proceeds to step 2410 to adjust the operating flow rate by an increment. If a confirmatory input is not received, or not received within a time period, then the controller may proceed to step 2412 to maintain the present operating flow rate.

In some examples, the determination that the operating flow rate be adjusted, and/or the proposed new operating flow rate determined by the controller may be presented as a suggestion to a user rather than being automatically implemented by the controller. The controller may be configured to present one or more prompts to the user in relation to the proposed new operating flow rate and allow for user input. The user input may similarly be configured to provide confirmation of the proposed operating flow rate, and/or allow for adjustment of the proposed operating flow rate before confirmation.

In some additional examples, the controller may be configured to store the operating flow rate at the end of a therapy session in memory. At the end of each therapy session, the controller may store the latest operating flow rate in memory. At the initiation of the next therapy session, at step 2402 the stored operating flow rate may be used as the initial operating flow rate for the therapy session.

2.3.1 Flow Control Method using Cardiorespiratory Index Figure 22 illustrates a flow chart of an example of a method 4100 for controlling the operating flow rate of gas delivered to a patient using a cardiorespiratory index based on a measured respiratory rate and a measured heart rate of a patient. The process or method 4100 can be implemented by any of the systems and apparatus described herein. The process or method 4100 may for example be implemented by the control system 2320.

The process or method 4100 may be performed continually or continuously over a therapy session. In some examples, the therapy session may be a single therapy session defined from a commencement of therapy being provided at a certain flow rate until the end of the therapy being provided at, below or above a certain flow rate. In some examples, the flow rate defining the commencement and end of therapy may be any flow rate at or above 0 1/min.

The control system 2320 can adjust the operating flow rate of the gases delivered or provided by the respiratory therapy device or apparatus 2202. The control system 2320 follows the iterative process or method 4100 discussed below of titration to find a substantially optimal operating flow rate using feedback from one or more sensors. A substantially optimal operating flow rate may be a flow rate at which a patient’s respiratory rate or heart rate or a cardiorespiratory index is at or close to a minimum. Additionally, in some examples, a substantially optimal operating flow rate may be a flow rate at which a patient’s respiratory rate and/or heart rate is within a range.

The control system 2320 can, for example, increase the motor speed of the blower when a blower is used as the flow source 2224 to increase the operating flow rate of gases through the respiratory assistance system 10, 2200. The control system 2320 can measure one or more patient conditions in response to changes to one or more system parameters. The control system 2320 can measure the patient’s respiratory rate and heart rate in response to changes to the operating flow rate.

The method 4100 is similar to the previously described method of 2400 but uses a cardiorespiratory index to control the operating flow rate. m. Cardiorespiratory Index

The cardiorespiratory index for a patient is based on a respiratory rate and a heart rate of the patient. The cardiorespiratory index may provide an indication of a patient’s work of breathing (WOB) and the flow control method may be configured to minimise the patient’s WOB or to reduce this below a threshold. The method may be configured to adjust the operating flow rate to reduce or minimise the patient’s respiratory rate and/or heart rate. In some examples, the method may be configured to use the cardiorespiratory index to adjust the operating flow rate to find an optimum operating flow rate corresponding to a local minimum respiratory rate and/or heart rate. This optimum operating flow rate may correspond to an effective setting for therapy for the patient whilst also providing sufficient comfort for the patient to maintain the therapy.

In some examples, the cardiorespiratory index may be based on a time-averaged first patient parameter over a first respiratory measurement period, and a time-averaged second patient parameter over a second measurement period. The first patient parameter and the second patient parameter may be based on measurement signals received from respective sensors or from a common sensor.

The cardiorespiratory index may be determined using a predefined first patient parameter and a predefined second patient parameter. For example, a predefined first patient parameter may be indicative of a wanted or normal respiratory rate for a patient. A wanted or normal respiratory rate may differ for different patients, for example depending on their current heath conditions and status, as well as factors such as their age, weight, height, sex and sleep state (awake or asleep). The predefined first patient parameter may be provided as a clinician set value based on clinician evaluation of the patient or may be determined from historical data from the patient or from similar patients. In some examples a default value may be used.

In some examples, a predefined second patient parameter may be indicative of a wanted or normal heart rate for a patient. A wanted or normal heart rate may differ for different patients, for example depending on their current heath conditions and status, as well as factors such as their age, weight, height, sex and sleep state (awake or asleep). The predefined second patient parameter may be provided as a clinician set value based on clinician evaluation of the patient or may be determined from historical data from the patient or from similar patients. In some examples a default value may be used.

In some examples, the cardiorespiratory index may be based on a difference between a received or determined first patient parameter (e.g. a respiratory rate value) and the predefined first patient parameter. This difference could be a numerical value, a percentage difference, a standard deviation using historical first patient parameter data or some other difference metric. For example, for a predefined first patient parameter of 20 (breaths per minute) and a received or determined first patient parameter of 30, the difference could be 10 or 50% depending on configuration; other difference metrics could alternatively be used for the first patient parameter. This difference is sometimes referred to herein as a first patient parameter (or respiratory rate) index.

In some examples, the cardiorespiratory index may also be based on a difference between a received or determined second patient parameter (e.g. a heart rate value) and the predefined second patient parameter. This difference could be a numerical value, a percentage difference, a standard deviation using historical second patient parameter data or some other difference metric. For example, for a predefined second patient parameter of 60 (beats per minute) and a received or determined second patient parameter of 90, the difference could be 30 or 50% depending on configuration; other difference metrics could alternatively be used for the second patient parameter. This difference is sometimes referred to herein as a second patient parameter (or heart rate) index.

In some examples, the cardiorespiratory index may add the first patient parameter difference (or respiratory rate index) to the second patient parameter difference (or heart rate index) using an appropriate weighting of the two values. In other examples, these two values may be averaged, or one or more other mathematical operation may be performed. In one example, a mathematical operation may determine a ratio of the first and second patient parameters or their differences from the respective predefined first and second patient parameters. In an example, a mathematical operation may determine the absolute value of the two differences so that the resulting cardiorespiratory index is always positive.

In some examples, the cardiorespiratory index may use an operation which applies an exponential weighting to the first patient parameter difference and the second patient parameter difference. For example, the two differences may each be squared and added together, they may then be square rooted. In some examples, the root mean square of the two differences may be used, that is the square root of the average of the squared differences of the first and second patient parameters. This has the effect of amplifying the cardiorespiratory index when one of the patient parameter differences is large, even if the other patient parameter difference is small, or both patient parameter differences are moderate. It may be preferable to have the respiratory rate and the heart rate 20% above their respective predefined values rather than having one at 40% above and the other at 0% above. These cardiorespiratory index examples generate a lower value when both respiratory rate and heart rate are kept close to their predefined or desired values but increases significantly when one these parameters (e.g. RR) diverges significantly from its respective predefined value, even if the other parameter (e.g. HR) remains close to its respective predefined value. The cardiorespiratory index will not rise as much when both parameters (e.g. RR and HR) diverge slightly or moderately from their respective predefined values.

In some examples, a falling cardiorespiratory index may correspond with a falling (or an optimal) respiratory rate or a respiratory rate that is stable or not rising rapidly. A falling cardiorespiratory index may additionally or alternatively correspond with a falling (or an optimal) heart rate or a heart rate that is stable or not rising rapidly. An increasing cardiorespiratory index may correspond with a rising, sub-optimal or non-stable respiratory rate and/or a rising, sub-optimal or non-stable heart rate.

In some examples, multiple cardiorespiratory indices may be employed, for example a first cardiorespiratory index may be an average of the difference associated with the first patient parameter and the difference associated with the second patient parameter. A second cardiorespiratory index may be a ratio of the first patient parameter to the second patient parameter. These two cardiorespiratory indices may then be used together for the controlling the operating flow rate.

Upon determining the cardiorespiratory index, the method may then be used to change the operating flow rate to reduce the cardiorespiratory index as described herein. n. Initial operating flow rate

The process 4100 can begin at block 4101 with the respiratory therapy device 2202 receiving or determining an initial operating flow rate for the delivery of a gas flow to the patient. The gas flow is provided at at least an operating flow rate. In some examples, the operating flow rate is sufficient to provide high flow therapy to the patient in use, such as within the ranges of flow rates as previously discussed. The control system 2320 may set an initial operating flow rate. The control system may also set other operating parameters of the respiratory therapy device or respiratory apparatus 2202. The operating parameters of the respiratory therapy device 2202 may control the characteristics of the flow of gases delivered or provided by the respiratory therapy device 2202.

As described previously, the initial operating flow rate may be manually set by a clinician. This may be input using an interface such as a graphical user interface (GUI), a dial or knob or using a communications interface with a remote device such as an App on the clinician’s Smartphone. In an example, a range for the operating flow rate may also be manually set by a clinician. The clinician set initial flow rate may be based on the clinician’s assessment of an optimal operating flow rate based on factors such as the patient’s age, weight, height, sex and sleep state (awake or asleep). Other factors such as the patient’s medical conditions and status may also or alternatively be used, for example presence of coughing and/or sputum production, as well as any medical diseases or diagnoses the patient has. Further, other factors such as the time of day and the therapy type may also be used.

Alternatively, the initial and/or range for the operating flow rate may be pre-set or stored in a memory. In some examples the controller 2320 may determine this using user or clinician inputs such as the patient’s medical conditions and status, and/or their age, weight, height, sex and sleep state (awake or asleep). In some examples, the initial and/or range for the operating flow rate may be based on historical data for the patient, for example a previous operating flow rate at which the cardiorespiratory index was lowest may initially be used. In some examples, historical date for similar patients may be used to determine an initial and/or range for the operating flow rate to start with.

The initial and/or range for the operating flow rate may alternatively be determined based on one or more additional parameters. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like, and/or system parameters including time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the initial and/or range for the operating flow rate.

Once the initial operating flow rate has been received or determined, the process 4100 proceeds to start the high flow therapy using the initial operating flow rate at step 4102. o. Intervals

Once therapy has commenced, and gas flow is provided by the respiratory therapy device at an operating flow rate, the process 4100 then proceeds to start an iterative control loop comprising steps 4104 to 4014. The iterative control loop is performed at intervals, and comprises, at said intervals, performing the steps 4104 to 4014.

In some examples, an interval is defined by the control system 2320 waiting for a time interval before performing each of steps 4104 to 4110/4112. For example, the control system 2320 can wait for a time interval before proceeding to perform the steps of 4104 to 4110/4112. This step is shown by block 4114 of the process 4100. The step 4114 of waiting for an interval may be performed before step 4104, and after step 2410 or 2412 has been performed, such that there is a delay between performing each iteration of the control loop of the process 4100. It will be appreciated that steps 4104 to 4110/4112 may be performed substantially in the same time interval.

As previously described with respect to method 2400, the time interval may be a fixed time interval. The fixed time interval may be the same interval for each iteration of the control loop. In some examples, the fixed time interval is a pre-set time interval. For example, the pre-set time period can be less than 10 minutes or greater than or equal to 10 minutes. In such examples, the pre-set time interval may be between about 1 minute to about 8 hours. The pre-set time interval may be for example 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes, or 45 minutes, or 1 hour, or 1 hour and 30 minutes, or 2 hours.

In other examples, the time interval is a variable time interval. The variable time interval may be different or have the option of being different between each interval for each iteration of the control loop. The variable time interval may be based on a calculation or determination, for example the calculation or determination of the cardiorespiratory index for a preceding interval. In some examples, the variable time interval may be based on the respiratory rate and/or heart rate of the patient, and/or the status of the respiratory rate and/or heart rate of the patient, and/or one or more devices and/or patient sensor readings, and/or the amount of time in the therapy session. In some examples, the variable time period is calculated or determined by the control system 2320 at each interval. In further examples, the time period is set to a first value when the cardiorespiratory index of the patient is within a first range, and to at least a second value when the cardiorespiratory index of the patient is within a second range. For example, if the control system 2320 determines that the patient’s cardiorespiratory index decreasing and/or increasing at a certain rate above a threshold between intervals, the time period may be set to a first value. If the control system 2320 determines that the patient’s cardiorespiratory rate is decreasing and/or increasing at a certain rate below a threshold between intervals, the time period may be set to a second value. The first value may be shorter than the second value. In other embodiments, the first value may be greater than the second value. Further thresholds and corresponding values are envisaged. p. Measuring or determining respiratory rate

At block 4104, the control system 2320 receives or determines a first patient parameter indicative of the patient’s respiratory rate as previously discussed in relation to step 2404 of Figure 6. q. Measuring or determining heart rate

At block 4105, the control system 2320 receives or determines a second patient parameter indicative of the patient’s heart rate as previously described in relation to step 2405 of Figure 6. r. Determining a cardiorespiratory index

At block 4106, the control system 2320 determines a cardiorespiratory index based on the measured or determined first patient parameter and the received or determined second patient parameter. The cardiorespiratory parameter may be determined in any suitable manner, for example as described above.

As noted above, in one example, the cardiorespiratory index may be based on a difference between the measured or determined first patient parameter and a predefined first patient parameter as well as a difference between the measured or determined second patient parameter and a predefined second patient parameter. These two differences may be provided in any suitable format such as a percentage difference or variance, and the cardiorespiratory index may be a function of these two differences, such as the root mean square, although other functions could alternatively be used. s. Determining whether to adjust or maintain operating flow rate

At block 4108, the control system 2320 can then determine whether to adjust or maintain the operating flow rate, based on the cardiorespiratory index of the patient.

In some examples, the process 4100 may determine at block 4108 that the operating flow rate should be adjusted if the cardiorespiratory index is outside a predefined cardiorespiratory index threshold. Conversely, the process 4100 may determine at block 4108 that the operating flow rate should be maintained if the cardiorespiratory index is within the predefined cardiorespiratory index threshold. In some examples, this may correspond to determining that the operating flow rate should be adjusted if the cardiorespiratory index is greater than or equal to a certain value, and maintaining the operating flow rate if the cardiorespiratory index is below that value.

In some examples, the process 4100 may determine at block 4108 that the operating flow rate should be adjusted if the cardiorespiratory index is increasing above a predefined rate, and maintained otherwise. In some examples, the process 4100 may determine at block 4108 that the operating flow rate should be maintained if the cardiorespiratory index is stable over a number of intervals, and adjusted otherwise.

The predefined cardiorespiratory index threshold and/or predefined rate of increase may be set by a clinician or stored on the control system 2320. One or both of these values may be determined based on factors such as the patient’s age, weight, height, sex, medical conditions and status, as well as historical data of the patient or similar patients, such as previous stable cardiorespiratory indices.

In some examples, the process 4100 may determine at block 4108 that the operating flow rate should be maintained if the cardiorespiratory index is at a local minimum, or adjusted otherwise. A local minimum may be determined based on historical data indicating one or more minimums in cardiorespiratory index at different operating flow rates. If the cardiorespiratory index is within a predefined tolerance of one of these minimums, then the control system 2320 may determine to maintain the operating flow rate, or otherwise to adjust it. This could be overridden by other considerations such as a rapidly rising cardiorespiratory index. Alternatively or additionally, the decision on whether to adjust or maintain the operating flow rate may be based on determining whether or not the patient’s respiratory rate and/or heart rate is within a predefined tolerance of a local minimum. t. Adjust the operating flow rate dependent on the cardiorespiratory index

At block 4010, the control system 2320 adjusts the operating flow rate depending on the cardiorespiratory index. For example, if the cardiorespiratory index is higher than a predefined cardiorespiratory index threshold, the control system 2320 at step 4110 may determine that the operating flow rate be increased (or decreased). The level of the increase may be dependent on the cardiorespiratory index, for example if this is significantly higher than the predefined cardiorespiratory index threshold a larger increase (or decrease) may be employed compared to a situation where the index is only slightly higher than the threshold.

In other examples the operating flow rate may be adjusted by an increment in which the operating flow rate is increased or decreased by a certain value, amount or increment. The increment may be a fixed value or may be a fixed time increment during which the operating flow rate is increased or decreased for a pre-set time. In another example the increment may be a variable value increment or a variable time increment based on the cardiorespiratory index and/or patient sensor readings and/or the amount of time in the therapy session.

Whether fixed or variable, the increment may be automatically determined based on one or more additional parameters. The one or more additional parameters may be inputted by the user and/or stored in memory. The one or more additional parameters may correspond to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the increment.

The increment may be between about 0.1 1/min and about 201/min, optionally it may be between about 0.5 1/min and about 15 1/min, optionally it may be between about 1 1/min and about 10 1/min, optionally it may be between about 2 1/min and about 8 1/min, optionally it may be between about 3 1/min and about 6 1/min, preferably it may be about 5 1/min. In some examples where the first increment above the initial operating flow rate yields an increase in the cardiorespiratory index, the titration process should begin decreasing the flow rate in increments to find the minimum cardiorespiratory index or reduce this below a predefined cardiorespiratory index threshold.

In another example, the increments may be proportional to the difference between the cardiorespiratory index determined at the present interval and the predefined cardiorespiratory index threshold. For example, if the patient has a cardiorespiratory index much higher than the threshold, then the increments used are larger such that the cardiorespiratory index is brought closer to the desired range at a quicker rate. As this difference becomes smaller, so too do the increments in flow rate used.

In some examples, the cardiorespiratory index may be positive or negative and if this is negative and greater than a predefined negative cardiorespiratory index threshold, the control system 2320 at step 4110 may determine that the operating flow rate be decreased.

In some examples, the control system 2320 at step 4110 uses the cardiorespiratory index and one or more previous adjustments to the operating flow rate to determine whether to increase or decrease the operating flow rate. For example, if the operating flow rate was increased in the previous interval, and the cardiorespiratory index of the present interval is higher than the previous interval, then the control system 2320 may determine that the operating flow rate be decreased. Conversely, if the operating flow rate was increased in the previous interval, and the cardiorespiratory index of the present interval is lower than the previous interval, then the control system 2320 may determine that the operating flow rate be further increased. Similarly, if the operating flow rate was decreased in the previous interval, and the cardiorespiratory index of the present interval is higher than the previous interval, then the control system 2320 may determine that the operating flow rate be increased. Conversely, if the operating flow rate was decreased in the previous interval, and the cardiorespiratory index of the present interval is lower than the previous interval, then the control system 2320 may determine that the operating flow rate be further decreased. u. Maintaining the operating flow rate

At block 4112, the control system 2320 may maintain the operating flow rate based on the control system determining at block 4108 that said operating flow rate be maintained. As discussed above, at step 4108, if the patient’s cardiorespiratory index is substantially stable, or is below a predefined cardiorespiratory index threshold or is otherwise at a minimum, then the control system 2320 may determine that the operating flow rate be maintained. At step 4112, the control system 2320 proceeds to maintain the operating flow rate, as discussed above.

The control system may determine a local minimum by monitoring the cardiorespiratory index (CRI) in response to two or more changes in operating flow rate. For example, if the control system increases the operating flow rate and the CRI decreases, then the control system again increases the operating flow rate but the CRI increases, then the optimal flow rate or local minimum is at the previous operating flow rate (i.e. after the first increase in operating flow rate). Similarly, if the control system decreases the operating flow rate a number of times and each time the CRI falls, then after a further decrease in operating flow rate the CRI increases, the minimum CRI is at the preceding operating flow rate. v. Waiting for interval

At block 4114, after the control system 2320 either adjusts the operating flow rate at step 4110, or maintains the operating flow rate at step 4112, the process 4100 then proceeds to wait for a time interval before performing each of steps 4104 to 4110/4112 again, as previously discussed.

For example, the control system 2320 can wait for a time interval before proceeding to perform the steps of 4104 to 4110/4112. This step is shown by block 4114 of the process 4100. As such that there is a delay between performing each iteration of the control loop of the process 4100. It will be appreciated that steps 4104 to 4110/4112 may be performed substantially in the same time interval.

In some examples, the control system 2320 may perform an initial titration sequence using the process 4100, in which the operating flow rate is relatively quickly adjusted from the initial operating flow rate to an optimum flow rate at which the cardiorespiratory index is at a minimum. In the titration mode the intervals may be relatively short, such as every 5 minutes, so that the optimal flow rate for the patient is quickly found. The control system may then move to a calibration mode using the process 4100, as described in more detail below. In the calibration mode, the intervals may be longer, for example every 1 hour. In some examples, the control system may move directly to the calibration mode after starting at the initial operating flow rate. w. Calibrations

Over time, a patient’s condition may change. For example, their condition may improve or deteriorate, resulting in different biochemistry that means the level of respiratory support required to minimise work of breathing is different. As such, the substantially optimal operating flow rate may change as a result of a patient’s changing condition. The controller may regularly perform a ‘calibration’ that determines if the current operating flow rate is still the substantially optimal operating flow rate or if the current operating flow rate remains suitable for the patient’s prevailing condition.

To perform the calibration, the controller may take respiratory rate and heart rate measurements at the current operating flow rate, at a (first) flow rate an increment above the operating flow rate (i.e., an upper flow rate), and at a (second) flow rate an increment below the operating flow rate (i.e., a lower flow rate).

Suitable non-limiting examples for the time interval may be 5 minutes, 10 minutes, or 15 minutes. The increment may be between 2 and 10 L/min, preferably 5 L/min.

The controller may determine a cardiorespiratory index at the upper and lower flow rates, relative to the cardiorespiratory index at the operating flow rate. Based on this, if the cardiorespiratory index is lower at the upper or lower flow rates, the controller may recalibrate to the operating flow rate with the lowest cardiorespiratory index, to suit the patient’s changing condition. However, if the cardiorespiratory index at the upper or lower flow rates is higher than the cardiorespiratory index at the current flow rate, the controller may maintain the current flow rate as the optimal operating flow rate for the patient.

Using the method 4100 as a non-limiting example, steps 4104 to 4107 to determine the cardiorespiratory index may comprise the controller, at each interval and/or at a defined time interval, determining or receiving a first patient parameter and a second patient parameter at the present (or maintained) operating flow rate, at a first flow rate above the operating flow rate (e.g., by an increment), and at a second flow rate below the operating flow rate (e.g., by an increment). The controller may then use the first patient parameter and the second patient parameter at the present operating flow rate (i.e., the present respiratory rate and heart rate), the first patient parameter and the second patient parameter at the first flow rate (i.e., the higher flow respiratory and heart rates), and the first patient parameter and the second patient parameter at the second flow rate (i.e., the lower flow respiratory and heart rates) to determine the cardiorespiratory index at these different flow rates. The respective cardiorespiratory index at these different flow rates may be compared relative to one another.

In these examples, step 4104 of method 4100 comprises the controller, in any order, determining or receiving the first patient parameter at the present operating flow rate; increasing the operating flow rate by an increment above the present operating flow rate, and determining or receiving the first patient parameter at the increased operating flow rate; decreasing the flow rate to be an increment below the present operating flow rate, and determining or receiving the first patient parameter at the decreased operating flow rate. In some examples, further first patient parameters are determined or received at one or more additional increments above and/or below the operating flow rate.

Similarly, in these examples, step 4105 of method 4100 comprises the controller, in any order, determining or receiving the second patient parameter at the present operating flow rate; increasing the operating flow rate by an increment above the present operating flow rate, and determining or receiving the second patient parameter at the increased operating flow rate; decreasing the flow rate to be an increment below the present operating flow rate, and determining or receiving the second patient parameter at the decreased operating flow rate. In some examples, further second patient parameters are determined or received at one or more additional increments above and/or below the operating flow rate.

In some examples, determination or receiving of the first and second patient parameters at one or each of the present, decreased, and/or increased operating flow rates comprise waiting for a time interval for the patient to respond to the change in flow rate before determining or receiving of the first and second patient parameters. The time interval and flow increment may be as described herein.

In these examples, step 4106 of method 4100 comprises determining the cardiorespiratory index on assessment of the first and second patient parameters taken at the present operating flow rate (i.e., the present respiratory rate), at the one or more increments above the operating flow rate (i.e., the higher flow respiratory rate(s)), and at the one or more increments below the operating flow rate (i.e., the lower flow respiratory rate(s)).

The controller is configured to assess the higher flow cardiorespiratory index and determines whether the higher flow cardiorespiratory index indicates that the patient’s respiratory rate is stable or increasing and/or the patient’s heart rate is stable or increasing. For example, a large rise in higher flow cardiorespiratory index may indicate that one or both of the patient’s respiratory rate and heart rate is not stable. The controller similarly assesses the lower flow cardiorespiratory index and determines whether the lower flow cardiorespiratory index indicate the patient’s respiratory rate is stable or increasing and/or the patient’s heart rate is stable or increasing. For example, a large rise in the lower flow cardiorespiratory index may indicate that one or both of the patient’s respiratory rate and heart rate is not stable.

As such, the controller may be configured to assess the cardiorespiratory index at the operating flow rate, at one or more increments above the operating flow rate, and at one or more increments below the operating flow rate. Based on the assessment, the controller may determine the patient’s respiratory rate and/or heart rate at the operating flow rate is stable, is increasing, or is decreasing; and similarly at the one or more increments above the operating flow rate is stable, is increasing, or is decreasing; and at the one or more increments below the operating flow rate is stable, is increasing, or is decreasing. According to one non-limiting example, the cardiorespiratory index is a calculated by weighting the proportional difference between the received or determined first patient parameter (based on respiratory rate) and a predefined first patient parameter and the proportional difference between the received or determined first patient parameter (based on respiratory rate). The larger the difference, for either parameter, the larger the effect on the cardiorespiratory index. For example, an exponential function may be applied to the differences to prioritise large differences over the average difference. This prioritises getting both parameters close to their predefined values. For example, if the first patient parameter rate (e.g. respiratory rate - RR) is 30% above its respective predefined value and the second patient parameter (e.g. heart rate - HR) is 10% below its respective predefined value, the cardiorespiratory index may have a value of (30² + 10²) = 30.33. On the other hand if RR is 20% below its respective predefined value and HR is 20% above its respective predefined value, the cardiorespiratory index has a value of (20²+20²) = 28.28. The second cardiorespiratory index is lower in the second scenario than the first scenario, even though the absolute magnitude of the differences is the same. As noted, this prioritises the system identifying and rectifying larger departures from the desired respiratory rate and heart rate.

According to another non-limiting example, the cardiorespiratory index is the average of the proportional difference between the received or determined first patient parameter (based on respiratory rate) and a predefined first patient parameter and the proportional difference between the received or determined first patient parameter (based on respiratory rate). For example, if the received or determined respiratory rate is 30% above the predefined respiratory rate and the received or determined heart rate is 10% below the predefined heart rate, then the cardiorespiratory index is 20%. Upon an increase in operating flow rate, if the respiratory rate were to fall to 10% above the predefined respiratory rate and the heart rate were to increase to the predefined heart rate (i.e. 0% difference), then the cardiorespiratory index would fall to 5%, representing an improvement to the patient’s condition at the higher flow rate. The controller may then recalibrate the operating flow rate to that higher rate.

Alternatively, other functions or mathematical operations may be used for calculating the cardiorespiratory index in some examples.

If there is no significant change in cardiorespiratory index (outside a predefined tolerance or threshold), the controller may determine at step 4108 to maintain the operating flow rate. If there is a significant improvement in cardiorespiratory index at the higher or lower flow rate, then controller may determine at step 4108 to adjust the operating flow rate to that corresponding to the improved cardiorespiratory index. The controller may then implement this determination at steps 4110/4112 as previously described. x. Determining patient status using the cardiorespiratory index

In some examples, the control system 2320 may determine a status of the patient based on the cardiorespiratory index determined at one or more previous intervals. In some examples, the status is determined based on comparing said cardiorespiratory index at the present interval, to at the cardiorespiratory index determined at one or more previous intervals. In some examples, the status is based at least on comparing said determined cardiorespiratory index to the cardiorespiratory index determined at the most recent previous interval. In examples such as the above, said comparison may indicate the change of the cardiorespiratory index between two or more intervals.

The status may be used to indicate that the patient’s respiratory rate and/or heart rate is stable. This may be inferred by only small or no changes in cardiorespiratory index over an assessment period. Conversely, a change in cardiorespiratory index over the assessment period may indicate a change in the patient's respiratory rate or heart rate or both. An increase in cardiorespiratory index corresponds to an increase in respiratory rate, heart rate or both.

In some examples, based on the status indicating that the respiratory rate and/or heart rate is stable, the controller may maintain the operating flow rate and perform an iterative process of continuing to receive or determined the patient’s respiratory rate, heart rate and cardiorespiratory index, and determine the status at further intervals. Based on the status indicating that the respiratory rate and/or heart rate is not stable, the controller may adjust the operating flow rate at further intervals until the status indicates that the patient’s respiratory rate and/or heart rate is stable.

In some examples, determining the status may comprise determining a first or respiratory rate status based on a respiratory rate index, and determining a second or heart rate status based on a heart rate index. The first or respiratory rate index may be determined based on a difference between a received or determined first patient parameter and a predefined first patient parameter. The second or heart rate index may be determined based on a difference between a received or determined second patient parameter and a predefined second patient parameter. The first and second indices may be used to determine the cardiorespiratory index.

In some examples, the step of determining the first status may include calculating by the control system 2320 the rate of the change of the patient’s respiration rate over time. The first status may be determined based on assessing a rate of change of the first or respiratory rate index. The rate of change of said index may be determined based on a calculation which uses the first patient parameter received or determined at the present interval, and one or more first patient parameters received or determined at one or more previous intervals. The control system 2320 may determine a derivative of a function using the one or more first patient parameters in the function. In some examples, the first status may be a state of a patient’s respiratory rate. The state of the patient’s respiratory rate may be for example grouped into a category. In some examples, the category may be such as ‘stable’ or ‘reducing’ (or ‘decreasing’) or ‘increasing’.

As previously described, the control system 2320 may indicate that the first status is ‘stable’ if the comparison or determination or calculation indicates that the change in patient’s respiratory rate is below a threshold. As previously described, the first status may be determined using a gradient or rate of change of the patient’s respiratory rate between different flow rates.

As previously described, the control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy, based on the first status.

Similarly, in some examples, the step of determining the second status may include calculating by the control system 2320 the rate of the change of the patient’s heart rate over time. The second status may be determined based on assessing a rate of change of the second or heart rate index. The rate of change of said index may be determined based on a calculation which uses the second patient parameter received or determined at the present interval, and one or more second patient parameters received or determined at one or more previous intervals. The control system 2320 may determine a derivative of a function using the one or more second patient parameters in the function. In some examples, the second status may be a state of a patient’s heart rate. The state of the patient’s heart rate may be for example grouped into a category. In some examples, the category may be such as ‘stable’ or ‘reducing’ (or ‘decreasing’) or ‘increasing’. As previously described, the control system 2320 may indicate that the second status is ‘stable’ if the comparison or determination or calculation indicates that the change in patient’s heart rate is below a threshold. As previously described, the second status may be determined using a gradient or rate of change of the patient’s heart rate between different flow rates.

As previously described, the control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy, based on the second status. y. Control of oxygen concentration level

In some examples, control of the flow of gases to the patient may include adjusting the oxygen concentration level of the gases as well as their operating flow rate. This may be implemented by receiving or determining, based on data from one or more sensors, a third patient parameter indicative of a blood oxygen saturation level of the patient. If the third patient parameter indicates that the patient’s blood oxygen saturation level is below a stable threshold, then the oxygen concentration level in the gas flow to the patient is adjusted to improve the blood oxygen saturation level to at least the stable threshold. The stable threshold may be clinician set or a default value such as 95%, although other values could be used.

A control loop may be used to automatically adjust the oxygen concentration level of the gases, for example as described in section 2.5 below. In some examples, adjusting the oxygen concentration level of the gases delivered to the patient may be performed at the same time as the steps relating to optimising operating flow rate at the previously discussed intervals. In some examples, the determination about whether to adjust the oxygen concentration level of the gases delivered to the patient, and if needed adjusting this, may be performed at different intervals to the control loop used to determined and if needed adjust the operating flow rate of the gases delivered to the patient. The interval used to optimise the patient’s blood oxygen saturation level may be shorter than the interval used for optimising the operating flow rate. In an example, the interval for the oxygen saturation level control may be 5-6 minutes and the interval for the operating flow rate control may be 15-30 minutes. z. Additional/alternative implementations

In some alternative examples, the control system may be configured to perform steps 4102, 4104 and 4105 initially. The control system may then be configured to display the patient parameter indicative of the patient’s respiratory rate and heart rate and/or cardiorespiratory index to the user via the display of the respiratory therapy apparatus, or a display of an external device in operative communication with the respiratory therapy apparatus and forming a part of the respiratory therapy system. In some examples, alongside the display of the patient parameters indicative of the patient’s respiratory rate and heart rate and the cardiorespiratory index, an indication of the operative flow rate may also be shown.

Additionally, a user input may be able to be received by the control system. The display may be configured to allow a user interface such as by way of a touchscreen which provides for the user input. In some examples the user input may be provided by one or more buttons, knobs, or dials of the respiratory therapy apparatus. The user input is configured to allow the user to adjust the operating flow rate manually. The adjustment of the operating flow rate performed by the user based on the displayed indication of the patient’s respiratory rate and/or heart rate (or other patient parameter such as cardiorespiratory index).

In some further examples, the method 4100 may further comprise prompting the user based on the decision at step 4108. In these examples, once step 4108 has determined that the operating flow rate be adjusted, the user is prompted that the operating flow rate is being adjusted via the display. The new operating flow rate, and in some examples the previous operating flow rate, may additionally be presented to the user via the display. As such, the user is informed of the changing of the adjustment to the operating flow rate.

In other examples, once step 4108 has determined that the operating flow rate be adjusted, the user is prompted that the controller has determined that the operating flow rate should be adjusted. In such examples, the user is prompted to confirm whether the adjustment to the operating flow rate should proceed. The user can provide input in response to the prompting, for example via the display. Once a confirmatory input has been received from the user, the controller proceeds to step 4110 to adjust the operating flow rate by an increment. If a confirmatory input is not received, or not received within a time period, then the controller may proceed to step 4112 to maintain the present operating flow rate.

2.4 High Flow Rate Oscillations

The delivered flow rate may be oscillated over a time period. This may involve the delivery of therapy at flow rates oscillating between two set points. The oscillations may be sinusoidal, saw-tooth, rectangular (i.e., discrete) or any other suitable oscillatory mechanism.

This therapy mode may have the advantages of generally keeping work of breathing at a sufficiently low level, but ensuring that the patient does not become fully reliant on the therapy, which may help with long term patient recovery.

In one example, the two set points may be set by a clinician or preset by the therapy device. For example, the lower set point may be 20 LPM and the upper set point may be 40 LPM.

In another example, the set points may be based on the optimal flow rate, FM, as described herein. Once the optimal flow rate is identified after the titration period, the set points may be a predetermined distance above and below the optimal flow rate. For example, the set points may be ± 30% of the optimal flow rate. As a non-limiting example, if the optimal flow rate is 30 LPM, the set points may be ± 9 LPM; the lower set point may be 21 LPM and the upper set point may be 39 LPM.

In another example, the set points may be based on the curves of respiratory rate and heart rate against flow rate. For example, the lower set point may be the point on the respiratory rate curve just before the sharp decrease in respiratory rate, while the upper set point may be the point on the heart rate curve just after the sharp increase in heart rate. The points may be at the ends of the plateau as opposed to the peaks before/after the related sharp changes. As a further example, the set points may be where the respiratory rate and the heart rate transition from an ‘increasing’ or ‘decreasing’ status to a ‘stable’ status. As a further example, the set points may be points of inflection in the curves of respiratory rate and heart rate against flow rate.

The oscillations will have a time period - the time taken per full oscillation cycle. This may be half an hour, in one example. Generally, the range of flow rates covered are chosen such that work of breathing is minimised.

2.5 Combinations

In a further example, the therapy may begin in an optimising work of breathing mode. As the patient’s condition improves, the machine or respiratory apparatus may then enter the oscillatory mode. The size of the oscillations (i.e., the range between lower and upper set flow rates) may increase as the patient further improves. To achieve this, the lower set flow rate may progressively decrease while the upper set flow rate remains constant.

The techniques disclosed herein may also incorporate closed loop SpO2 control. A NHF therapy apparatus, e.g., respiratory apparatus 60 (Figure 1), may include a blower and a humidifier in a housing. The housing has an 02 inlet and an ambient air inlet. The 02 and air may be mixed in the blower or in a mixture within the apparatus. The blower is controlled to provide a set flow rate. Motor speed may be controlled to operate the blower to generate a set flow rate. The blower may be controlled to provide a constant flow rate. The 02 inlet may include a controllable valve e.g., a proportional valve. The flow rate may be controlled by a closed loop control based on flow sensor measurements. The apparatus is controlled to provide High Flow Therapy. A pulse oximeter may be electrically coupled to the controller of the apparatus. The pulse oximeter measures a patient’ s blood oxygen saturation (SpO2). A target range of blood oxygen saturation can be set by a clinician. The apparatus includes a 02 sensor, preferably an ultrasonic sensor, to measure the fraction of 02 in the gases (FdO2). The ultrasonic sensor provides fast and accurate measurements. The controller is configured to automatically control the 02 valve to adjust the 02 fraction (FdO2) provided to the patient to maintain the measured SpO2 within the target SpO2 range.

In some cases, a patient may begin undergoing high flow therapy while already at a deteriorated condition, whereby SpO2 levels are suboptimal or below a stable threshold. In such cases, it may be required to restore SpO2 to optimal levels quickly. As such, the controller may use a closed loop SpO2 control in conjunction with closed loop RR and HR control. The closed loop SpO2 control may be employed to deliver the gas flow to the patient at an operating oxygen concentration level to improve the patient’s SpO2 level to the optimal levels or higher, e.g., an SpO2 level that is at least at the stable threshold. The SpO2 level may be restored to beyond or higher than the stable threshold. The operating oxygen concentration level may be set by a clinician. At the beginning of high flow therapy, the controller may receive an SpO2 reading. If SpO2 is below a threshold, FiO2 may be titrated to restore SpO2 to a stable level, as described in PCT Pub. No. WO 2019/070136, titled “Closed Loop Oxygen Control”, which is hereby incorporated by reference in its entirety.

The RR and HR titration of flow rate, as described herein, may take place either subsequently to the stabilisation of SpO2, or simultaneously with the SpO2 closed loop control. As the SpO2 control titrates FiO2, and the RR/HR titration controls flow rate, the two closed loop control methods may be operated simultaneously and independently. In some examples, the closed loop SpO2 control may operate at shorter more frequent intervals than the closed loop RR and HR control. This allows the control system to be more responsive to patient’s SpO2 levels.

In one example, at the start of therapy, the SpO2 control of FiO2 may operate until the SpO2 is stable (i.e., above a threshold). Once SpO2 has been at a stable condition for a time threshold, such as 10 to 30 minutes, or preferably 15 minutes, then the SpO2 control may be disabled by the controller and the RR/HR flow rate control may be enabled.

In another example, at the start of therapy, SpO2 control of FiO2 and RR/HR control of flow rate may operate simultaneously. Once SpO2 has been stable for a time threshold, the SpO2 control may be disabled, or may continue running indefinitely.

2.6 Warnings

The control system 2320 can also generate alarms or warnings based on the measured physiological patient parameters. For instance, if the respiration rate and/or the heart rate exceeds or drops below an acceptable limit, the control system 2320 can generate an alarm for the display and/or sound an audio alarm. Alternatively, the control system can generate alarms or warnings based on relative insensitivity of measured parameters to changes in flow. For example, if the patient parameter such as respiratory rate and/or heart rate is insensitive to flow this may indicate that the therapy is less likely to be efficacious. In an embodiment, the control system 2320 can change the flow rate and determine that the patient parameter such as respiratory rate and/or heart rate is not affected significantly by the flow rate change. Based on the lack of correlation, the control system 2320 can determine that the therapy may not be optimal for the patient. 2.7 Applications

The respiratory assistance system 10, 2200 with high flow therapy can be used to provide support to patients in emergency rooms, intensive care units (ICU), the operating room (OR), other hospital areas or in-home. In particular, the respiratory assistance system 10, 2200 can be used to support a patient under anaesthesia, during preoxygenation and post operation. Using high flow therapy can have advantages in some embodiments because the patient can still communicate, and the mouth is not covered by a mask. Any time a patient requires intubation or endoscopy, the mouth may be blocked and cannot be used for providing invasive air support. Accordingly, high flow therapy along with the nasal cannula configuration of the respiration assistance system 10, 2200 can be used in those situations to provide breathing support. The control system 2320 can determine a patient’s respiratory rate and/or heart rate or other physiological parameters in these cases and automatically determine a set value for flow rate. When patients use the respiratory assistance system 10, 2200 in their homes, the control system 2320 can be used to adjust the set value of flow rate at the initial stage. The patient can also measure their respiration rate and/or heart rate and enter the rate(s) using the controller.

2.8 Measure of Efficacy

The respiratory rate and heart rate, and/or the cardiorespiratory index may provide a useful indication of the efficacy of the high flow therapy. For example, these biological parameters may be monitored for a predetermined period of time, for example 30 minutes, after the patient commences high flow therapy or at various intervals thereafter. Any change in respiratory rate and heart rate, and/or cardiorespiratory index over this period may then be used by clinicians to evaluate the efficacy of the therapy, and determine if the patient may need more escalated care, or if the current settings are sufficient. For example, an improved cardiorespiratory index may indicate the current level of care is sufficient, while an increasing cardiorespiratory index or a cardiorespiratory index which is stable above a certain threshold may indicate that escalation is required. Similarly, a reduced respiratory rate and/or heart rate may indicate the current level of care is sufficient, while an increasing respiratory rate and/or heart rate or a respiratory rate and/or heart rate which is stable above a certain threshold may indicate that escalation is required.

Terminology and definitions

The phrases 'computer-readable medium' or ‘machine-readable medium’ as used in this specification and claims should be taken to include, unless the context suggests otherwise, a single medium or multiple media. Examples of multiple media include a centralised or distributed database and/or associated caches. These multiple media store the one or more sets of computer executable instructions. The phrases 'computer-readable medium' or ‘machine- readable medium’ should also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor of a computing device and that cause the processor to perform any one or more of the methods described herein. The computer-readable medium is also capable of storing, encoding or carrying data structures used by or associated with these sets of instructions. The phrases 'computer-readable medium' and ‘machine readable medium’ include, but are not limited to, portable to fixed storage devices, solid-state memories, optical media or optical storage devices, magnetic media, and/or various other mediums capable of storing, containing or carrying instruction(s) and/or data. The ‘computer- readable medium’ or ‘machine-readable medium’ may be non-transitory.

The term ‘comprising’ as used in this specification and claims means ‘consisting at least in part of or ‘including, but not limited to’ such that it is to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense. When interpreting each statement in this specification and claims that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

The term ‘and/or’ means ‘and’ or ‘or’, or both.

The use of ‘(s)’ following a noun means the plural and/or singular forms of the noun. Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.

Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

In the above description, specific details are given to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, software modules, functions, circuits, etc., may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail. In other instances, well-known modules, structures and techniques may not be shown in detail in order not to obscure the embodiments.

Also, it is noted that the embodiments may be described as a process that is depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process is terminated when its operations are completed. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc., in a computer program. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or a main function.

Aspects of the systems and methods described above may be operable on any type of general purpose computer system or computing device, including, but not limited to, a desktop, laptop, notebook, tablet, smart television, gaming console, or mobile device. The term "mobile device" includes, but is not limited to, a wireless device, a mobile phone, a smart phone, a mobile communication device, a user communication device, personal digital assistant, mobile handheld computer, a laptop computer, wearable electronic devices such as smart watches and headmounted devices, an electronic book reader and reading devices capable of reading electronic contents and/or other types of mobile devices typically carried by individuals and/or having some form of communication capabilities (e.g., wireless, infrared, short-range radio, cellular etc.).

Aspects of the systems and methods described above may be operable or implemented on any type of specific-purpose or special computer, or any machine or computer or server or electronic device with a microprocessor, processor, microcontroller, programmable controller, or the like, or a cloud-based platform or other network of processors and/or servers, whether local or remote, or any combination of such devices.

Furthermore, embodiments may be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine-readable medium such as a storage medium or other storage(s). A processor may perform the necessary tasks. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc. In the above description, a storage medium may represent one or more devices for storing data, including read-only memory (ROM), random access memory (RAM), magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other machine or computer readable mediums for storing information.

The various illustrative logical blocks, modules, circuits, elements, and/or components described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic component, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, circuit, and/or state machine. A processor may also be implemented as a combination of computing components, e.g., a combination of a DSP and a microprocessor, a number of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The methods or algorithms described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executable by a processor, or in a combination of both, in the form of processing unit, programming instructions, or other directions, and may be contained in a single device or distributed across multiple devices. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD- ROM, or any other form of storage medium known in the art. A storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.

One or more of the components and functions illustrated the figures may be rearranged and/or combined into a single component or embodied in several components without departing from the scope of the disclosure. Additional elements or components may also be added without departing from the scope of the disclosure. Additionally, the features described herein may be implemented in software, hardware, as a business method, and/or combination thereof. In its various aspects, embodiments of the disclosure can be embodied in a computer- implemented process, a machine (such as an electronic device, or a general-purpose computer or other device that provides a platform on which computer programs can be executed), processes performed by these machines, or an article of manufacture. Such articles can include a computer program product or digital information product in which a computer readable storage medium containing computer program instructions or computer readable data stored thereon, and processes and machines that create and use these articles of manufacture.

Although this disclosure has been described in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the disclosure have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. For example, features described above in connection with one embodiment can be used with a different embodiment described herein and the combination still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above. Accordingly, unless otherwise stated, or unless clearly incompatible, each embodiment of this disclosure may comprise, additional to its essential features described herein, one or more features as described herein from each other embodiment of the invention disclosed herein.

This disclosure may also be said broadly to consist in the parts, elements and features referred to or indicated in this disclosure, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this disclosure relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure in the context of separate implementations or examples can also be implemented in combination in a single implementation or example. Conversely, various features that are described in the context of a single implementation or example can also be implemented in multiple implementations or examples separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a sub-combination or variation of a sub-combination.

Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

The scope of the present disclosure is not intended to be limited by the specific disclosures of embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

The following numbered clauses define particular aspects and embodiments contemplated herein: Clauses:

1. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status; and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

2. The method according to clause 1, wherein the method further comprises delivering the gas flow to the patient via the patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more patient characteristics.

3. The method according to clauses 1 or 2, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least one of the first status or the second status.

4. The method according to any preceding clause, wherein the one or more sensors are configured to be attached to or located near to the patient to measure the first patient parameter and the second patient parameter.

5. The method according to any preceding clause, wherein receiving or determining the first patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.

6. The method according to clause 5, wherein the one or more sensors store a plurality of instantaneous measurements of the respiratory rate over the measurement period and calculate the time-averaged respiratory rate.

7. The method according to any preceding clause, wherein receiving or determining the second patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged heart rate over a measurement period.

8. The method according to clause 7, wherein the one or more sensors store a plurality of instantaneous measurements of the heart rate over the measurement period and calculate the time-averaged heart rate.

9. The method according to any preceding clause, wherein determining the first status comprises performing a first comparison comparing the first patient parameter received or determined at the present interval to the first patient parameter received or determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals.

10. The method according to clause 9, wherein the first status relates to a degree or amount of change between the first patient parameter received or determined at the present interval to the first patient parameter received or determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals, based on said second comparison.

11. The method according to clause 10, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is substantially stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

12. The method according to clause 11, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

13. The method according to clause 11 or clause 12, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the first status indicating that the respiratory rate is substantially stable and the second status indicating that the heart rate is substantially stable.

14. The method according to any preceding clause, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises: comparing the first status to one or more first thresholds; and comparing the second status to one or more second thresholds.

15. The method according to clause 14, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises determining that the operating flow rate be adjusted in response to determination that the first status fails to satisfy the one or more first thresholds and/or the second status fails to satisfy the one or more second thresholds.

16. The method according to clause 12, wherein the step of adjusting the operating flow rate by the increment comprises increasing the operating flow rate by the increment based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

17. The method according to clause 16, wherein the increment is a variable increment, the variable increment based on at least the first status and the second status.

18. The method according to clause 13, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of a previous increment.

19. The method according to any preceding clause, further comprising, after maintaining the operating flow rate, performing a calibration of the operating flow rate at defined time intervals.

20. The method according to clause 19, wherein performing the calibration comprises, at each defined time interval of the defined time intervals: determining the first status and the second status at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the first status and the second status; determining, at a second flow rate lower than the maintained operating flow rate, the first status and the second status; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other. 21. The method according to clause 20, wherein performing the calibration further comprises, at the each defined time interval: determining, at a third flow rate higher than the first flow rate, the first status and the second status; determining, at a fourth flow rate lower than the second flow rate, the first status and the second status; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other.

22. The method according to any preceding clause, wherein the method is performed continually over a therapy session.

23. The method according to any preceding clause, wherein the gas flow is delivered to the patient at conditions suitable for provision of high flow therapy.

24. The method according to any preceding clause, wherein the method further comprises delivering the gas flow at an operating oxygen concentration level.

25. The method according to clause 24, further comprising: receiving or determining, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and if the blood oxygen saturation is determined to be below a stable threshold, delivering the gas flow comprises adjusting an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

26. The method according to clause 25, wherein adjusting the oxygen concentration level is performed prior to performing the steps at the intervals.

27. The method according to clause 25, wherein adjusting the oxygen concentration level is performed simultaneously with performing the steps at the intervals. 28. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating the respiratory rate is stable and the second status indicating the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

29. The method according to clause 28, wherein the step of receiving or determining the first patient parameter and the second patient parameter occurs at a predetermined time period after adjusting the operating flow rate.

30. The method according to clause 28 or clause 29, wherein the first status indicating the respiratory rate is stable comprises determining said first status is within a first range or threshold, and wherein the second status indicating that the heart rate is stable comprises determining said second status is within a second range or threshold. 31. The method according to clause 30, wherein the first status indicating the respiratory rate is no longer stable comprises determining said first status is outside the first range or threshold, wherein the second status indicating the heart rate is no longer stable comprises determining said second status is outside the second range or threshold.

32. The method according to any of clauses 28 to 31, wherein the method further comprises delivering the gas flow to the patient via the patient interface at an initial operating flow rate, wherein the initial flow rate is determined based on one or more patient characteristics.

33. The method according to any of clauses 28 to 32, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least one of the first status or the second status.

34. The method according to any of clauses 28 to 33, wherein the one or more sensors are configured to be attached to or located near to the patient to measure the first patient parameter and the second patient parameter.

35. The method according to any of clauses 28 to 34, wherein receiving or determining the first patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.

36. The method according to clause 35, wherein the one or more sensors store a plurality of instantaneous measurements of the respiratory rate over the measurement period and calculate the time-averaged respiratory rate.

37. The method according to any of clauses 28 to 36, wherein receiving or determining the second patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged heart rate over a measurement period.

38. The method according to clause 37, wherein the one or more sensors store a plurality of instantaneous measurements of the heart rate over the measurement period and calculate the time-averaged heart rate. 39. The method according to any one of clauses 28 to 38, wherein determining the first status comprises performing a first comparison comparing the first patient parameter received or determined at the present interval to the first patient parameter received or determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals.

40. The method according to clause 39, wherein the first status relates to a degree or amount of change between the first patient parameter received or determined at the present interval to the first patient parameter received or determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals, based on said second comparison.

41. The method according to clause 40, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

42. The method according to clause 41, wherein the step of determining whether the respiratory rate is unstable comprises the first status indicating that the respiratory rate is increasing or decreasing, and wherein the step of determining whether the heart rate is unstable comprises the second status indicating that the heart rate is increasing or decreasing.

43. The method according to any of clauses 28 to 42, wherein the step of progressively applying a plurality of flow rate values as the operating flow rate comprises increasing the operating flow rate by an increment at each interval.

44. The method according to clause 43, wherein said increment is a variable increment, the variable increment based on at least the first status and the second status.

45. The method according to any of clauses 28 to 44, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of a previous increment.

46. The method according to any of clauses 28 to 45, further comprising, after maintaining the operating flow rate, performing a calibration of the operating flow rate at defined time intervals.

47. The method according to clause 46, wherein performing the calibration comprises, at each defined time interval of the defined time intervals: determining the first status and the second status at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the first status and the second status; determining, at a second flow rate lower than the maintained operating flow rate, the first status and the second status; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other.

48. The method according to clause 47, wherein performing the calibration further comprises, at the each defined time interval: determining, at a third flow rate higher than the first flow rate, the first status and the second status; determining, at a fourth flow rate lower than the second flow rate, the first status and the second status; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other.

49. The method according to any of clauses 28 to 48, wherein the method is performed continually over a therapy session.

50. The method according to any of clauses 28 to 49, wherein the gas flow is delivered to the patient at conditions suitable for provision of high flow therapy.

51. The method according to any of clauses 28 to 50, wherein the method further comprises delivering the gas flow at an operating oxygen concentration level.

52. The method according to clause 51, further comprising: receiving or determining, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and if the blood oxygen saturation is determined to be below a stable threshold, delivering the gas flow comprises adjusting an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

53. The method according to clause 52, wherein adjusting the oxygen concentration level is performed prior to progressively applying the plurality of flow rate values.

54. The method according to clause 52, wherein adjusting the oxygen concentration level is performed simultaneously with progressively applying the plurality of flow rate values.

55. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

56. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

57. The respiratory therapy system according to clause 55 or the respiratory apparatus according to clause 56, wherein determining the first status comprises performing a first comparison comparing the first patient parameter received or determined at the present interval to the first patient parameter received or determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals.

58. The respiratory therapy system or apparatus according to clause 57, wherein the first status relates to a degree or amount of change between the first patient parameter received or determined at the present interval to the first patient parameter received or determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals, based on said second comparison.

59. The respiratory therapy system or apparatus according to clause 58, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is substantially stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

60. The respiratory therapy system or apparatus according to clause 59, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

61. The respiratory therapy system or apparatus according to clause 59 or clause 60, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the first status indicating that the respiratory rate is substantially stable and the second status indicating that the heart rate is substantially stable.

62. The respiratory therapy system or apparatus according to any of clauses 55 to 61, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises: comparing the first status to one or more first thresholds; and comparing the second status to one or more second thresholds.

63. The respiratory therapy system or apparatus according to clause 62, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises determining that the operating flow rate be adjusted in response to determination that the first status fails to satisfy the one or more first thresholds and/or the second status fails to satisfy the one or more second thresholds.

64. The respiratory therapy system or apparatus according to clause 60, wherein the step of adjusting the operating flow rate by the increment comprises increasing the operating flow rate by the increment based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

65. The respiratory therapy system or apparatus according to clause 64, wherein the increment is a variable increment, the variable increment based on at least the first status and the second status.

66. The respiratory therapy system or apparatus according to clause 61, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of a previous increment.

67. The respiratory therapy system or apparatus according to any of clauses 55 to 66, wherein the controller is further configured to deliver the flow of gases to the user at an operating oxygen concentration level.

68. The respiratory therapy system or apparatus according to clause 67, wherein the controller is further configured to: receive or determine, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and for delivering the flow of gases and if the blood oxygen saturation is determined to be below a stable threshold, adjust an oxygen concentration level in the flow of gases to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

69. The respiratory therapy system or apparatus according to clause 68, wherein the controller is configured to adjust the oxygen concentration level prior to performing the steps at the intervals.

70. The respiratory therapy system or apparatus according to clause 68, wherein the controller is configured to adjust the oxygen concentration level simultaneously with performing the steps at the intervals.

71. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

72. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable. 73. The respiratory therapy system according to clause 71 or the respiratory apparatus according to clause 72, wherein the step of receiving or determining the first patient parameter and the second patient parameter occurs at a predetermined time period after adjusting the operating flow rate.

74. The respiratory therapy system or apparatus according to any of clauses 71 to 73, wherein the first status indicating the respiratory rate is stable comprises determining said first status is within a first range or threshold, and wherein the second status indicating that the heart rate is stable comprises determining said second status is within a second range or threshold.

75. The respiratory therapy system or apparatus according to clause 74, wherein the first status indicating the respiratory rate is no longer stable comprises determining said first status is outside the first range or threshold, and wherein the second status indicating the heart rate is no longer stable comprises determining said second status is outside the second range or threshold.

76. The respiratory therapy system or apparatus according to any of clauses 71 to 75, wherein determining the first status comprises performing a first comparison comparing the first patient parameter received or determined at the present interval to the first patient parameter received or determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals.

77. The respiratory therapy system or apparatus according to clause 76, wherein the first status relates to a degree or amount of change between the first patient parameter received or determined at the present interval to the first patient parameter received or determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals, based on said second comparison.

78. The respiratory therapy system or apparatus according to clause 77, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is substantially stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

79. The respiratory therapy system or apparatus according to clause 78, wherein the step of determining whether the respiratory rate is unstable comprises the first status indicating that the respiratory rate is increasing or decreasing, and wherein the step of determining whether the heart rate is unstable comprises the second status indicating that the heart rate is increasing or decreasing.

80. The respiratory therapy system or apparatus according to any of clauses 71 to 79, wherein the step of progressively applying a plurality of flow rate values as the operating flow rate comprises increasing the operating flow rate by an increment at each interval.

81. The respiratory therapy system or apparatus according to clause 80, wherein said increment is a variable increment, the variable increment based on at least the first status and the second status.

82. The respiratory therapy system or apparatus according to any of clauses 71 to 81, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of a previous increment.

83. The respiratory therapy system or apparatus according to any of clauses 71 to 82, wherein the controller is further configured to deliver the flow of gases to the user at an operating oxygen concentration level.

84. The respiratory therapy system or apparatus according to clause 83, wherein the controller is further configured to: receive or determine, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and for delivering the flow of gases and if the blood oxygen saturation is determined to be below a stable threshold, adjust an oxygen concentration level in the flow of gases to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

85. The respiratory therapy system or apparatus according to clause 84, wherein the controller is configured to adjust the oxygen concentration level prior to progressively applying the plurality of flow rate values.

86. The respiratory therapy system or apparatus according to clause 84, wherein the controller is configured to adjust the oxygen concentration level simultaneously with progressively applying the plurality of flow rate values.

87. The respiratory therapy system or apparatus according to any of clauses 55 to 86, wherein the flow generator is further configured to deliver the flow of gases to the user via a patient interface at an initial operating flow rate, and wherein the initial operating flow rate is determined based on one or more patient characteristics.

88. The respiratory therapy system or apparatus according to any of clauses 55 to 87, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least one of the first status or the second status.

89. The respiratory therapy system or apparatus according to any of clauses 55 to 88, wherein the one or more are configured to be attached to or located near to the user to measure the first patient parameter and the second patient parameter.

90. The respiratory therapy system or apparatus according to any of clauses 55 to 89, wherein receiving or determining the first patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.

91. The respiratory therapy system or apparatus according to clause 90, wherein the one or more sensors are configured to store a plurality of instantaneous measurements of the respiratory rate over the measurement period and further configured to calculate the time- averaged respiratory rate.

92. The respiratory therapy system or apparatus according to any of clauses 55 to 91, wherein receiving or determining the second patient parameter comprises receiving data from the one or more sensors indicative of a time-averaged heart rate over a measurement period.

93. The respiratory therapy system or apparatus according to clause 92, wherein the one or more sensors are configured to store a plurality of instantaneous measurements of the heart rate over the measurement period and further configured to calculate the time-averaged heart rate.

94. The respiratory therapy system or apparatus according to any of clauses 55 to 91, wherein the controller is further configured to, after the operating flow rate is maintained, perform a calibration of the operating flow rate at defined time intervals.

95. The respiratory therapy system or apparatus according to clause 94, wherein, for performing the calibration, the controller is configured to, at each defined time interval of the defined time intervals: determine the first status and the second status at the maintained operating flow rate; determine, at a first flow rate higher than the maintained operating flow rate, the first status and the second status; determine, at a second flow rate lower than the maintained operating flow rate, the first status and the second status; and adjust or maintain the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other.

96. The respiratory therapy system or apparatus according to clause 95, wherein the controller is further configured to, at the each defined time interval: determine, at a third flow rate higher than the first flow rate, the first status and the second status; determine, at a fourth flow rate lower than the second flow rate, the first status and the second status; and adjust or maintain the maintained operating flow rate depending on a comparison of the first status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other, and a comparison of the second status at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other. 97. The respiratory therapy system or apparatus according to any of clauses 55 to 96, wherein the steps are performed at said intervals continually over a therapy session.

98. The respiratory therapy system or apparatus according to any of clauses 55 to 97, wherein the flow of gases is delivered to the user at conditions suitable for provision of high flow therapy.

99. The respiratory therapy system or apparatus according to any of clauses 55 to

98, further comprising a humidifier configured to humidify the flow of gases.

100. The respiratory therapy system or apparatus according to any of clauses 55 to

99, wherein the system or apparatus further comprises a non-transitory computer-readable medium that is accessible or in data communication with the controller, and preferably wherein the non-transitory computer-readable medium comprises a non-volatile memory having stored thereon computer executable instructions that, when executed on the controller or a processing device or devices, cause the controller or processing device or devices to perform or execute any one or more of the steps or methods or aspects described in any one of clauses 55 to 99.

101. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to: receive or determine, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

102. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to: receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

103. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to, based on the first status and the second status, adjust the operating flow rate continually until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

104. A method for determining an operating flow rate of gas delivered to a patient, the method comprising: delivering a gas flow to the patient via a patient interface; at intervals, progressively applying a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a first status of the respiratory rate based at least on the first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on the second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining a first stable region corresponding to the first status indicating the respiratory rate is stable, the first stable region being subsequent to a first non- stable region corresponding to the first status indicating the respiratory rate is non-stable; determining a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being before a second non-stable region corresponding to the second status indicating the heart rate is non-stable; and determining a flow rate value that is within the first stable region and the second stable region as the operating flow rate for the gas flow.

105. The method according to clause 104, wherein determining the first stable region comprises determining a first inflection point corresponding to a transition from the first non-stable region to the first stable region, wherein determining the second stable region comprises determining a second inflection point corresponding to a transition from the second stable region to the second non-stable region, and wherein determining the flow rate value comprises determining the flow rate value based on a first flow rate value corresponding to the first inflection point and a second flow rate value corresponding to the second inflection point.

106. The method according to clause 105, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is substantially equidistant from the first flow rate value and the second flow rate value.

107. The method according to clause 105, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the first flow rate value compared to the second flow rate value.

108. The method according to clause 105, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the second flow rate value compared to the first flow rate value.

109. The method according to any of clauses 104 to 108, further comprising: comparing the first status to one or more first thresholds; and comparing the second status to one or more second thresholds, wherein determining the flow rate value further comprises determining, as the operating flow rate, the flow rate value that corresponds to the first status satisfying the one or more first thresholds and the second status satisfying the one or more second thresholds.

110. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, wherein the controller is further configured to, at intervals: progressively apply a plurality of flow rate values for the flow of gases; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determine a first status of the respiratory rate based at least on the first patient parameter and the first patient parameter received or determined at one or more previous intervals; determine a second status of the heart rate based at least on the second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to: determine a first stable region corresponding to the first status indicating the respiratory rate is stable, the first stable region being subsequent to a first non-stable region corresponding to the first status indicating the respiratory rate is non-stable; determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being before a second non- stable region corresponding to the second status indicating the heart rate is non-stable; and determine a flow rate value that is within the first stable region and the second stable region as an operating flow rate for the flow of gases.

111. The respiratory apparatus according to clause 110, wherein the controller is configured to: for determining the first stable region, determine a first inflection point corresponding to a transition from the first non-stable region to the first stable region, for determining the second stable region, determine a second inflection point corresponding to a transition from the second stable region to the second non-stable region, and for determining the flow rate value, determine the flow rate value based on a first flow rate value corresponding to the first inflection point and a second flow rate value corresponding to the second inflection point.

112. The respiratory apparatus according to clause 111, wherein the controller is configured to, for determining the flow rate value, determine, as the operating flow rate, the flow rate value that is substantially equidistant from the first flow rate value and the second flow rate value.

113. The respiratory apparatus according to clause 111, wherein the controller is configured to, for determining the flow rate value, determine, as the operating flow rate, the flow rate value that is closer to the first flow rate value compared to the second flow rate value.

114. The respiratory apparatus according to clause 111, wherein the controller is configured to, for determining the flow rate value, determine, as the operating flow rate, the flow rate value that is closer to the second flow rate value compared to the first flow rate value.

115. The respiratory apparatus according to any of clauses 110 to 114, wherein the controller is further configured to: compare the first status to one or more first thresholds; and compare the second status to one or more second thresholds, wherein, for determining the flow rate value, determine, as the operating flow rate, the flow rate value that corresponds to the first status satisfying the one or more first thresholds and the second status satisfying the one or more second thresholds.

116. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; comparing the respiratory rate to a first threshold range associated with the respiratory rate; comparing the heart rate to a second threshold range associated with the heart rate; and in response to determination of at least one of the respiratory rate being outside of the first threshold range or the heart rate being outside of the second threshold range, adjusting the flow rate to effect the respiratory rate within the first threshold range and the heart rate within the second threshold range.

117. The method according to clause 116, further comprising repeating the process at intervals.

118. The method according to clause 116 or 117, wherein receiving or determining the respiratory rate and the heart rate comprises: receiving or determining the respiratory rate based on first data from a first sensor; and receiving or determining the heart rate based on second data from a second sensor.

119. The method according to clause 116 or 117, wherein receiving or determining the respiratory rate and the heart rate comprises receiving or determining the respiratory rate and the heart rate based on data from a single sensor.

120. The method according to any of clauses 116 to 119, further comprising, after effecting the respiratory rate within the first threshold range and the heart rate within the second threshold range, performing a calibration of the flow rate at defined time intervals. 121. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; compare the respiratory rate to a first threshold range associated with the respiratory rate; compare the heart rate to a second threshold range associated with the heart rate; and in response to determination of at least one of the respiratory rate being outside of the first threshold range or the heart rate being outside of the second threshold range, adjust the flow rate to effect the respiratory rate within the first threshold range and the heart rate within the second threshold range.

122. The respiratory apparatus according to clause 121, wherein the controller is configured to repeat the process at intervals.

123. The respiratory apparatus according to clause 121 or 122, wherein, for receiving or determining the respiratory rate and the heart rate, the controller is configured to: receive or determine the respiratory rate based on first data from a first sensor; and receive or determine the heart rate based on second data from a second sensor.

124. The respiratory apparatus according to clause 121 or 122, wherein, for receiving or determining the respiratory rate and the heart rate, the controller is configured to receive or determine the respiratory rate and the heart rate based on data from a single sensor.

125. The respiratory apparatus according to any of clauses 121 to 124, wherein the controller is further configured to, after the respiratory rate is effected within the first threshold range and the heart rate is effected within the second threshold range, perform a calibration of the flow rate at defined time intervals.

126. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: at intervals, progressively increasing the flow rate by a regular increment, at each of the intervals, receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining, based on the respiratory rate and the heart rate received or determined at the intervals, the flow rate that satisfies at least one condition of: a minimum respiratory rate, or a minimum heart rate, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold, and controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

127. The method according to clause 126, further comprising, in response to determining at least one of the respiratory rate failing to satisfy the first threshold or the heart rate failing to satisfy the second threshold, repeating the process to adjust the flow rate to effect the respiratory rate satisfying the first threshold and the heart rate satisfying the second threshold.

128. The method according to clause 126 or 127, further comprising controlling the flow generator to generate the flow of gases at an initial operating flow rate based on one or more patient characteristics.

129. The method according to any of clauses 126 to 128, further comprising, after controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition, performing, at defined time intervals, a calibration of the flow rate that satisfies the at least one condition.

130. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: at intervals, progressively increase the flow rate by a regular increment, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine, based on the respiratory rate and the heart rate received or determined at the intervals, the flow rate that satisfies at least one condition of: a minimum respiratory rate, or a minimum heart rate, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold, and control the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

131. The respiratory apparatus according to clause 130, wherein the controller is further configured to, in response to determination of at least one of the respiratory rate failing to satisfy the first threshold or the heart rate failing to satisfy the second threshold, repeat the process to adjust the flow rate to effect the respiratory rate satisfying the first threshold and the heart rate satisfying the second threshold.

132. The respiratory apparatus according to clause 130 or 131, wherein the controller is configured to control the flow generator to generate the flow of gases at an initial operating flow rate based on one or more patient characteristics.

133. The respiratory apparatus according to any of clauses 130 to 132, wherein the controller is further configured to, after controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition, perform, at defined time intervals, a calibration of the flow rate that satisfies the at least one condition.

134. A method for controlling a flow generator of a respiratory apparatus to provide a flow of gases to a user, the method comprising: continuously receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; operating the flow generator in a first mode comprising: generating the flow of gases at an initial flow rate; increasing the initial flow rate by a defined increment over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, receiving or determining, based on data from the one or more sensors, the respiratory rate and the heart rate; determining, based on the respiratory rate and the heart rate received or determined for the range of flow rates, a desired respiratory rate and a desired heart rate, and in response to determining the desired respiratory rate and the desired heart rate, operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate.

135. The method according to clause 134, wherein determining the desired respiratory rate and the desired heart rate comprises determining, as the desired respiratory rate and the desired heart rate, the respiratory rate and the heart rate that satisfy at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum respiratory rate, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum heart rate, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold.

136. The method according to clauses 134 or 135, further comprising, after generating the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate, performing, at defined time intervals, a calibration of the flow rate corresponding to the desired respiratory rate and the desired heart rate. 137. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, the controller being further configured to: continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; operate the flow generator in a first mode to: generate the flow of gases at an initial flow rate; increase the initial flow rate by a defined increment over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is to be delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, receive or determine, based on data from the one or more sensors, the respiratory rate and the heart rate; determine, based on the respiratory rate and the heart rate received or determined for the range of flow rates, a desired respiratory rate and a desired heart rate, and in response to the desired respiratory rate and the desired heart rate being determined, operate the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate.

138. The respiratory apparatus according to clause 137, wherein the controller is configured, for determining the desired respiratory rate and the desired heart rate, to determine, as the desired respiratory rate and the desired heart rate, the respiratory rate and the heart rate that satisfy at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum respiratory rate, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum heart rate, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold.

139. The respiratory apparatus according to clause 137 or 138, wherein the controller is further configured to, after generating the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate, perform, at defined time intervals, a calibration of the flow rate corresponding to the desired respiratory rate and the desired heart rate.

140. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, wherein the controller is further configured to repeat the steps throughout a therapy session for the respiratory therapy to adjust or maintain the operating flow rate throughout the therapy session. 141. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indictive of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index ; and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate depending on the cardiorespiratory index, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

142. The method according to clause 141, wherein the cardiorespiratory index is determined using a predefined first patient parameter and a predefined second patient parameter.

143. The method according to clause 142, wherein the predefined first patient parameter and/or the predefined second patient parameter is determined based on one or more of the following: received patient characteristics; a received clinician-set respiratory rate; a clinicianset first patient parameter; a clinician-set heart rate; a clinician-set second patient parameter; historical patient data; historical data relating to other patients; a default value.

144. The method according to clause 142 or 143, wherein the cardiorespiratory index is based on a difference between the received or determined first patient parameter and the predefined first patient parameter and a difference between the received or determined second patient parameter and the predefined second patient parameter.

145. The method according to any one of clauses 141 to 144, wherein adjusting the operating flow rate comprises adjusting the operating flow rate to reduce the cardiorespiratory index to a minimum or within a predefined cardiorespiratory index threshold. 146. The method of clause 145, wherein adjusting the operating flow rate comprises increasing or decreasing the operating flow rate by one or more increments dependent on the cardiorespiratory index.

147. The method of clause 146, wherein the increment is a variable increment based on the cardiorespiratory index.

148. The method according to any one of clauses 141 to 147, wherein determining whether to adjust or maintain the operating flow rate is based on the cardiorespiratory index being outside a predefined cardiorespiratory index threshold.

149. The method of any one of clauses 141 to 148, comprising issuing a warning responsive to the received or determined first patient parameter being outside a predefined first patient parameter range and/or the received or determined second patient parameter being outside a predefined second patient parameter range.

150. The method according to any one of clauses 141 to 149, wherein the method further comprises delivering the gas flow to the patient via the patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more of the following: received patient characteristics; a received clinician-set operating flow rate; a predetermined operating flow rate in a midrange between a minimum operating flow rate and a maximum operating flow rate; a predefined or default operating flow rate stored in a memory.

151. The method according to any one of clauses 141 to 150, further comprising, after maintaining the operating flow rate, performing a calibration of the operating flow rate at defined time intervals.

152. The method according to clause 151, wherein performing the calibration comprises, at each defined time interval of the defined time intervals: determining the cardiorespiratory index at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the cardiorespiratory index; determining, at a second flow rate lower than the maintained operating flow rate, the cardiorespiratory index; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, at the first flow rate and at the second flow rate relative to each other.

153. The method according to clause 152, wherein performing the calibration further comprises, at the each defined time interval: determining, at a third flow rate higher than the first flow rate, the cardiorespiratory index; determining, at a fourth flow rate lower than the second flow rate, the cardiorespiratory index; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other.

154. The method according to any one of clauses 141 to 153, comprising monitoring and recording one or more said indices over a predetermined period.

155. The method according to any one of clauses 141 to 154, wherein the intervals are spaced at a variable time period from each other, the variable time period based a said index.

156. The method according to any one of clauses 141 to 155, wherein the cardiorespiratory index is based on a time-averaged first patient parameter over a first measurement period and a time-averaged second patient parameter over a second measurement period.

157. The method according to any one of clauses 141 to 156, performing the steps of: determining a status of the patient based at least on the cardiorespiratory index, wherein determining the status comprises performing a comparison comparing the cardiorespiratory index determined at the present interval to the cardiorespiratory index determined at one or more previous intervals.

158. The method according to clause 157, wherein the status indicates that the respiratory rate and/or the heart rate is increasing, or is decreasing, or is substantially stable, based on said comparison. 159. The method according to clause 158, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status indicating that one of the respiratory rate or the heart rate is decreasing and that the other of the heart rate or the respiratory rate is substantially stable.

160. The method according to any one of clauses 141 to 159, wherein the method is performed continually over a therapy session or a predefined period.

161. The method according to any one of clauses 141 to 160, performing the steps of: receiving or determining, based on data from one or more sensors, a third patient parameter indicative of a blood oxygen saturation level of the patient; and if the blood oxygen saturation level is determined to be below a stable threshold, delivering the gas flow comprises adjusting an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation level to at least the stable threshold.

162. The method according to clause 161, wherein adjusting the blood oxygen saturation level is performed prior to performing the steps at the intervals.

163. The method according to clause 161, wherein adjusting the blood oxygen saturation level is performed simultaneously with performing the steps at the intervals.

164. The method according to clause 161, wherein adjusting the blood oxygen saturation level is performed second intervals, the second intervals being different to the first intervals.

165. The method according to clause 164, wherein the second intervals are more frequent than the first intervals.

166. The method according to any one of clauses 141 to 165, wherein determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index comprising determining whether the cardiorespiratory index corresponds to a local minimum respiratory rate and/or a local minimum heart rate. 167 The method according to clause 166, wherein adjusting the operating flow rate depending on the cardiorespiratory index comprises adjusting the operating flow rate to adjust the cardiorespiratory index to correspond with a local minimum for the respiratory rate or the a local minimum for the heart rate.

168. The method according to any one of clause 141 to 167, wherein adjusting the operating flow rate depending on the cardiorespiratory index comprises adjusting the operating flow rate to adjust the cardiorespiratory index to a local minimum.

169. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining a status of the patient based at least on said cardiorespiratory index and the cardiorespiratory index determined at one or more previous intervals ; based on the status indicating the respiratory rate and/or the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said respiratory rate, said heart rate and cardiorespiratory index, and determine, at further intervals, said status; and based on the status indicating the respiratory rate and/or the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the status indicates that the respiratory rate and/or the heart rate is stable.

170. The method according to clause 169, wherein the cardiorespiratory index is determined using a predefined first patient parameter and a predefined second patient parameter. 171. The method according to clause 170, wherein the predefined first patient parameter and/or the predefined second patient parameter is determined based on one or more of the following: received patient characteristics; a received clinician-set respiratory rate; a clinicianset first patient parameter; a clinician-set heart rate; a clinician-set second patient parameter; historical patient data; historical data relating to other patients; a default value.

172. The method according to clause 170 or 171 , wherein the cardiorespiratory index is based on a difference between the received or determined first patient parameter and the predefined first patient parameter and a difference between the received or determined second patient parameter and the predefined second patient parameter.

173. The method according to any one of clauses 169 to 172, wherein adjusting the operating flow rate comprises adjusting the operating flow rate to reduce the cardiorespiratory index to a minimum or within a predefined cardiorespiratory index threshold.

174. The method according to clause 169 to 173, wherein adjusting the operating flow rate comprises: increasing or reducing the operating flow rate by an increment

175. The method according to clause 174, wherein the increment is a variable increment based on the cardiorespiratory index.

176. The method according to any one of clauses 169 to 175, wherein determining whether to adjust or maintain the operating flow rate is based on the cardiorespiratory index being outside a predefined cardiorespiratory index threshold.

177. The method of any one of clauses 169 to 176, comprising issuing a warning responsive to the received or determined first patient parameter being outside a predefined first patient parameter range and/or the received or determined second patient parameter being outside a predefined second patient parameter range.

178. The method according to any one of clauses 169 to 177, wherein determining the status comprises: wherein determining the cardiorespiratory index comprises determining a respiratory rate index based on the received or determined first patient parameter and determining a heart rate index based on the received or determined first patient parameter determining a first status based at least on said respiratory rate index and the respiratory rate index received or determined at one or more previous intervals; determining a second status based at least on said heart rate index and the heart rate index received or determined at one or more previous intervals; wherein maintaining the operating flow rate is based on the respiratory rate index indicating the respiratory rate is stable and the heart rate index indicating the heart rate is stable; and wherein adjusting the operating flow rate at said further intervals until the first and/or second status indicates that the respiratory rate and/or the heart rate is stable is based on the respiratory rate index indicating the respiratory rate is no longer stable and/or the heart rate index indicating the heart rate is no longer stable.

179. The method according to clause 178, wherein the first status indicating the respiratory rate is stable comprises determining said first status is within a first range or threshold, and/or wherein the first status indicating the respiratory rate is no longer stable comprises determining said first status is outside the first range or threshold, wherein the second status indicating that the heart rate is stable comprises determining said second status is within a second range or threshold and/or wherein the second status indicating the heart rate is no longer stable comprises determining said second status is outside the second range or threshold.

180. The method according to clause 179, wherein determining the first status comprises performing a first comparison comparing the respiratory rate index determined at the present interval to the respiratory rate index determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the heart rate index determined at the present interval to the heart rate index determined at the one or more previous intervals.

181. The method according to clause 180, wherein the respiratory rate index relates to a degree or amount of change between the respiratory rate index determined at the present interval to the respiratory rate index determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the heart rate index determined at the present interval to the heart rate index determined at the one or more previous intervals, based on said second comparison.

182. The method according to clause 181, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

183. The method according to clause 182, wherein the step of determining whether the respiratory rate is unstable comprises the first status indicating that the respiratory rate is increasing or decreasing, and wherein the step of determining whether the heart rate is unstable comprises the second status indicating that the heart rate is increasing or decreasing.

184. The method according to any one of clauses 169 to 183, wherein the step of receiving or determining the respiratory rate, the heart rate and the cardiorespiratory index occurs at a predetermined time period after adjusting the operating flow rate.

185. The method according to any one of clauses 169 to 184, wherein the method further comprises delivering the gas flow to the patient via the patient interface at an initial operating flow rate, wherein the initial flow rate is determined based on one or more of the following: received patient characteristics; a received clinician-set operating flow rate; a predetermined operating flow rate in a midrange between a minimum operating flow rate and a maximum operating flow rate; a predefined or default operating flow rate stored in a memory.

186. The method according to any one of clauses 169 to 185, wherein the intervals are spaced at a variable time period from each other, the variable time period based on a said status. 187. The method according to any of clauses 169 to 186, wherein receiving or determining the respiratory rate comprises receiving data from the one or more sensors indicative of a time- averaged respiratory rate over a measurement period.

188. The method according to any of clauses 169 to 187, wherein receiving or determining the heart rate comprises receiving data from the one or more sensors indicative of a time- averaged heart rate over a measurement period.

189. The method according to any of clauses 169 to 188, further comprising, after maintaining the operating flow rate, performing a calibration of the operating flow rate at defined time intervals.

190. The method according to clause 189, wherein performing the calibration comprises, at each defined time interval of the defined time intervals: determining the cardiorespiratory index at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the cardiorespiratory index; determining, at a second flow rate lower than the maintained operating flow rate, the cardiorespiratory index; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other.

191. The method according to clause 190, wherein performing the calibration further comprises, at the each defined time interval: determining, at a third flow rate higher than the first flow rate, the cardiorespiratory index; determining, at a fourth flow rate lower than the second flow rate, the cardiorespiratory index; and adjusting or maintaining the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other. 192. The method according to any of clauses 169 to 191, wherein the method is performed continually over a therapy session.

193. The method according to any of clauses 169 to 192, wherein the gas flow is delivered to the patient at conditions suitable for provision of high flow therapy.

194. The method according to any of clauses 169 to 193, wherein the method further comprises delivering the gas flow at an operating oxygen concentration level.

195. The method according to clause 194, further comprising: receiving or determining, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and if the blood oxygen saturation is determined to be below a stable threshold, delivering the gas flow comprises adjusting an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

196. The method according to clause 195, wherein adjusting the oxygen concentration level is performed prior to progressively applying the plurality of flow rate values.

197. The method according to clause 195, wherein adjusting the oxygen concentration level is performed simultaneously with progressively applying the plurality of flow rate values.

198. The method according to clause 195, wherein adjusting the oxygen concentration level is performed second intervals, the second intervals being different to the first intervals.

199. The method according to clause 198, wherein the second intervals are more frequent than the first intervals.

200. A method for determining an operating flow rate of gas delivered to a patient, the method comprising: delivering a gas flow to the patient via a patient interface; at intervals, progressively applying a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determining a status of the respiratory rate based at least on the cardiorespiratory index and the cardiorespiratory index received or determined at one or more previous intervals; determining a first stable region corresponding to the status indicating the respiratory rate is stable, the stable region being subsequent to a non-stable region corresponding to the status indicating the respiratory rate is non-stable and/or determining a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being subsequent to a second non-stable region corresponding to the status indicating the heart rate is non-stable; determining a flow rate value that is within the first stable region and/or the second stable region as the operating flow rate for the gas flow.

201. The method according to clause 200, wherein determining the first stable region comprises determining a first inflection point corresponding to a transition from the first non-stable region to the first stable region, wherein determining the second stable region comprises determining a second inflection point corresponding to a transition from the second stable region to the second non-stable region, and wherein determining the flow rate value comprises determining the flow rate value based on a first flow rate value corresponding to the first inflection point and a second flow rate value corresponding to the second inflection point.

202. The method according to clause 201, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is substantially equidistant from the first flow rate value and the second flow rate value.

203. The method according to clause 201 , wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the first flow rate value compared to the second flow rate value. 204. The method according to clause 201, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the second flow rate value compared to the first flow rate value.

205. The method according to any of clauses 200 to 204, further comprising: comparing the status to one or more thresholds; and wherein determining the flow rate value further comprises determining, as the operating flow rate, the flow rate value that corresponds to the status satisfying the one or more first thresholds.

206. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; comparing the cardiorespiratory index to a threshold range associated with the cardiorespiratory index; and in response to determination of the cardiorespiratory index being outside of the threshold range, adjusting the flow rate to effect the cardiorespiratory index within the threshold range.

207. The method according to clause 206, further comprising repeating the process at intervals.

208. The method according to clause 206 or 207, wherein receiving or determining the respiratory rate and the heart rate comprises: receiving or determining the respiratory rate based on first data from a first sensor; and receiving or determining the heart rate based on second data from a second sensor. 209. The method according to clause 206 or 207, wherein receiving or determining the respiratory rate and the heart rate comprises receiving or determining the respiratory rate and the heart rate based on data from a single sensor.

210. The method according to any of clauses 206 to 209, further comprising, after effecting the cardiorespiratory index within the threshold range, performing a calibration of the flow rate at defined time intervals.

211. A method for controlling a flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at a flow rate; performing a process comprising: at intervals, progressively increasing or decreasing the flow rate by a regular increment or decrement, at each of the intervals, receiving or determining, based on data from one or more sensors, a respiratory rate of the user and/or a heart rate of the user; at each of the intervals, determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; determining, based on the cardiorespiratory index determined at the intervals, the flow rate that satisfies at least one condition of: a minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the cardiorespiratory index satisfying a threshold, and controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

212. The method according to clause 211, further comprising, in response to determining the cardiorespiratory index failing to satisfy the threshold, repeating the process to adjust the flow rate to effect the cardiorespiratory index satisfying the threshold.

213. The method according to clause 211 or 212, further comprising controlling the flow generator to generate the flow of gases at an initial operating flow rate based on one or more of the following: received patient characteristics; a received clinician-set predefined respiratory rate and/or heart rate; a predetermined respiratory rate and/or heart rate.

214. The method according to any one of clauses 211 to 213, further comprising, after controlling the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition, performing, at defined time intervals, a calibration of the flow rate that satisfies the at least one condition.

215. A method for controlling a flow generator of a respiratory apparatus to provide a flow of gases to a user, the method comprising: continuously receiving or determining, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determining a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; operating the flow generator in a first mode comprising: generating the flow of gases at an initial flow rate; increasing and/or decreasing the initial flow rate by a defined increment or decrement over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, determining, based on data from the one or more sensors, the cardiorespiratory index; determining, based on the cardiorespiratory index determined for the range of flow rates, a desired cardiorespiratory index , and in response to determining the desired cardiorespiratory index , operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index .

216. The method according to clause 215, wherein determining the desired cardiorespiratory index comprises determining, as the desired cardiorespiratory index, the cardiorespiratory index that satisfies at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the cardiorespiratory index satisfying a threshold.

217. The method according to clauses 215 or 216, further comprising, after generating the flow of gases at the flow rate corresponding to the desired cardiorespiratory index , performing, at defined time intervals, a calibration of the flow rate corresponding to the desired cardiorespiratory index .

218. The method according to any one of clauses 141 to 217, comprising monitoring the cardiorespiratory index for an efficacy assessment period and determining an efficacy measure based on a change in the cardiorespiratory index over the efficacy assessment period.

219. The method of clause 218, wherein the efficacy measure comprises one or more of the following: an indication that the treatment is sufficient based on the cardiorespiratory index reducing over the efficacy assessment period; an indication that the treatment is insufficient based on the cardiorespiratory index increasing or remaining stable over the efficacy assessment period.

220. A processor program product comprising processor instructions that when executed on a processor, causes the processor to perform any one of the methods of clauses 141 to 219.

221. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, perform the steps of: receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indictive of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index ; and based on determining that said operating flow rate be adjusted, operate the flow controller to adjust the operating flow rate depending on the cardiorespiratory index, and based on determining that said operating flow rate be maintained, operate the flow controller to maintain the operating flow rate at the present operating flow rate.

222. The apparatus according to clause 221, wherein the cardiorespiratory index is determined using a predefined first patient parameter and a predefined second patient parameter.

223. The apparatus according to clause 222, wherein the predefined first patient parameter and/or the predefined second patient parameter is determined based on one or more of the following: received patient characteristics; a received clinician-set respiratory rate; a clinicianset first patient parameter; a clinician-set heart rate; a clinician-set second patient parameter; historical patient data; historical data relating to other patients; a default value.

224. The apparatus according to clause 222 or 223, wherein the cardiorespiratory index is based on a difference between the received or determined first patient parameter and the predefined first patient parameter and a difference between the received or determined second patient parameter and the predefined second patient parameter.

225. The apparatus according to any one of clauses 221 to 224, wherein operating the flow generator to adjust the operating flow rate comprises operating the flow controller to adjust the operating flow rate to reduce the cardiorespiratory index to a minimum or within a predefined cardiorespiratory index threshold. 226. The apparatus of clause 225, wherein operating the flow generator to adjust the operating flow rate comprises operating the flow generator to increase or decrease the operating flow rate by one or more increments dependent on the cardiorespiratory index.

227. The apparatus of clause 226, wherein the increment is a variable increment based on the cardiorespiratory index.

228. The apparatus according to any one of clauses 221 to 227, wherein determining whether to adjust or maintain the operating flow rate is based on the cardiorespiratory index being outside a predefined cardiorespiratory index threshold.

229. The apparatus of any one of clauses 221 to 228, wherein the controller is configured to signal a warning responsive to the received or determined first patient parameter being outside a predefined first patient parameter range and/or the received or determined second patient parameter being outside a predefined second patient parameter range.

230. The apparatus according to any one of clauses 221 to 229, wherein the controller is configured to operate the flow generator to deliver the gas flow to the patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more of the following: received patient characteristics; a received clinician-set operating flow rate; a predetermined operating flow rate in a midrange between a minimum operating flow rate and a maximum operating flow rate; a predefined or default operating flow rate stored in a memory.

231. The apparatus according to any one of clauses 221 to 230, the controller configured to operate the flow generator to, after maintaining the operating flow rate, perform a calibration of the operating flow rate at defined time intervals.

232. The apparatus according to clause 231, wherein the controller is configured to perform the calibration at each defined time interval of the defined time intervals, by: determining the cardiorespiratory index at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the cardiorespiratory index; determining, at a second flow rate lower than the maintained operating flow rate, the cardiorespiratory index; and operating the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, at the first flow rate and at the second flow rate relative to each other.

233. The apparatus according to clause 232, wherein the controller is configured to perform the calibration at the each defined time interval, by: determining, at a third flow rate higher than the first flow rate, the cardiorespiratory index; determining, at a fourth flow rate lower than the second flow rate, the cardiorespiratory index; and operate the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other.

234. The apparatus according to any one of clauses 221 to 223, wherein the controller is configured to base the cardiorespiratory index on a time-averaged first patient parameter over a first measurement period and a time-averaged second patient parameter over a second measurement period.

235. The apparatus according to any one of clauses 221 to 224, wherein the controller is configured to: determine a status of the patient based at least on the cardiorespiratory index, wherein determining the status comprises performing a comparison comparing the cardiorespiratory index determined at the present interval to the cardiorespiratory index determined at one or more previous intervals.

236. The apparatus according to clause 235, wherein the status indicates that the respiratory rate and/or the heart rate is increasing, or is decreasing, or is substantially stable, based on said comparison.

237. The apparatus according to clause 236, wherein the controller is configured to determine whether to adjust the operating flow rate by determining that the operating flow rate be adjusted based on the status indicating that one of the respiratory rate or the heart rate is decreasing and that the other of the heart rate or the respiratory rate is substantially stable.

238. The apparatus according to any one of clauses 221 to 238, wherein the controller is configured to operate the flow generator over a therapy session or a predefined period.

239. The apparatus according to any one of clauses 221 to 238, wherein the controller is configured to: receive or determine, based on data from one or more sensors, a third patient parameter indicative of a blood oxygen saturation level of the patient; and if the blood oxygen saturation level is determined to be below a stable threshold, operate the flow generator adjust an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation level to at least the stable threshold.

240. The apparatus according to clause 239, wherein the controller is configured to operate the flow generator to adjust the blood oxygen saturation level prior to performing the steps at the intervals.

241. The apparatus according to clause 240, wherein the controller is configured to operate the flow generator to adjust the blood oxygen saturation level simultaneously with performing the steps at the intervals.

242. The apparatus according to any one of clauses 241 to 241, wherein the controller is configured to determine whether to adjust or maintain the operating flow rate by determining whether the cardiorespiratory index corresponds to a local minimum respiratory rate and/or a local minimum heart rate.

243. The apparatus according to clause 242, wherein the controller is configured to operate the flow generator to adjust the operating flow rate depending on the cardiorespiratory index to correspond with a local minimum for the respiratory rate or a local minimum for the heart rate.

244. The apparatus according to any one of clause 221 to 243, wherein the controller is configured to adjust the operating flow rate by adjusting the operating flow rate to adjust the cardiorespiratory index to a local minimum. 245. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, operate the flow generator to progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the patient based at least on said cardiorespiratory index and the cardiorespiratory index determined at one or more previous intervals ; based on the status indicating the respiratory rate and/or the heart rate is stable, operate the flow generator to maintain the operating flow rate, and perform an iterative process of continuing to receive or determine said respiratory rate, said heart rate and cardiorespiratory index, and determine, at further intervals, said status; and based on the status indicating the respiratory rate and/or the heart rate is no longer stable, operate the flow controller to adjust the operating flow rate at said further intervals until the status indicates that the respiratory rate and/or the heart rate is stable.

246. The apparatus according to clause 245, wherein the cardiorespiratory index is determined using a predefined first patient parameter and a predefined second patient parameter.

247. The apparatus according to clause 246, wherein the predefined first patient parameter and/or the predefined second patient parameter is determined based on one or more of the following: received patient characteristics; a received clinician-set respiratory rate; a clinician- set first patient parameter; a clinician-set heart rate; a clinician-set second patient parameter; historical patient data; historical data relating to other patients; a default value.

248. The apparatus according to clause 245 or 247, wherein the cardiorespiratory index is based on a difference between the received or determined first patient parameter and the predefined first patient parameter and a difference between the received or determined second patient parameter and the predefined second patient parameter.

249. The apparatus according to any one of clauses 245 to 248, wherein the controller is configured to operate the flow generator to adjust the operating flow rate by adjusting the operating flow rate to reduce the cardiorespiratory index to a minimum or within a predefined cardiorespiratory index threshold.

250. The apparatus according to clause 245 to 249, wherein the controller is configured to operate the flow generator to adjust the operating flow rate by increasing or reducing the operating flow rate by an increment.

251. The apparatus according to clause 250, wherein the increment is a variable increment based on the cardiorespiratory index.

252. The apparatus according to any one of clauses 245 to 251, wherein determining whether to adjust or maintain the operating flow rate is based on the cardiorespiratory index being outside a predefined cardiorespiratory index threshold.

253. The apparatus of any one of clauses 245 to 252, wherein the controller is configured to signal a warning responsive to the received or determined first patient parameter being outside a predefined first patient parameter range and/or the received or determined second patient parameter being outside a predefined second patient parameter range.

254. The apparatus according to any one of clauses 245 to 253, wherein the controller is configured to determine the status by: determining the cardiorespiratory index by determining a respiratory rate index based on the received or determined first patient parameter and determining a heart rate index based on the received or determined first patient parameter determining a first status based at least on said respiratory rate index and the respiratory rate index received or determined at one or more previous intervals; determining a second status based at least on said heart rate index and the heart rate index received or determined at one or more previous intervals; wherein operating the flow generator to maintain the operating flow rate is based on the respiratory rate index indicating the respiratory rate is stable and the heart rate index indicating the heart rate is stable; and wherein operating the flow generator to adjust the operating flow rate at said further intervals until the first and/or second status indicates that the respiratory rate and/or the heart rate is stable is based on the respiratory rate index indicating the respiratory rate is no longer stable and/or the heart rate index indicating the heart rate is no longer stable.

255. The apparatus according to clause 254, the controller is configured such that: determining the first status indicates the respiratory rate is stable comprises determining said first status is within a first range or threshold, and/or wherein the first status indicating the respiratory rate is no longer stable comprises determining said first status is outside the first range or threshold, determining the second status indicates that the heart rate is stable comprises determining said second status is within a second range or threshold and/or wherein the second status indicating the heart rate is no longer stable comprises determining said second status is outside the second range or threshold.

256. The apparatus according to clause 255, the controller configured such that: determining the first status comprises performing a first comparison comparing the respiratory rate index determined at the present interval to the respiratory rate index determined at one or more previous intervals, and determining the second status comprises performing a second comparison comparing the heart rate index determined at the present interval to the heart rate index determined at the one or more previous intervals.

257. The apparatus according to clause 256, wherein the respiratory rate index relates to a degree or amount of change between the respiratory rate index determined at the present interval to the respiratory rate index determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the heart rate index determined at the present interval to the heart rate index determined at the one or more previous intervals, based on said second comparison.

258. The apparatus according to clause 257, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

259. The apparatus according to clause 258, the controller configured such that: determining whether the respiratory rate is unstable comprises the first status indicating that the respiratory rate is increasing or decreasing, and determining whether the heart rate is unstable comprises the second status indicating that the heart rate is increasing or decreasing.

260. The apparatus according to any one of clauses 245 to 259, wherein the controller is configured to receive or determine the respiratory rate, the heart rate and the cardiorespiratory index at a predetermined time period after operating the flow generator to adjust the operating flow rate.

261. The apparatus according to any one of clauses 245 to 260, wherein the controller is configured to operate the flow generator to deliver the gas flow to the patient via the patient interface at an initial operating flow rate, wherein the initial flow rate is determined based on one or more of the following: received patient characteristics; a received clinician-set operating flow rate; a predetermined operating flow rate in a midrange between a minimum operating flow rate and a maximum operating flow rate; a predefined or default operating flow rate stored in a memory.

262. The apparatus according to any one of clauses 245 to 261, wherein the intervals are spaced at a variable time period from each other, the variable time period based on a said status. 263. The apparatus according to any of clauses 245 to 262, wherein the controller is configured to receive or determine the respiratory rate by receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.

264. The apparatus according to any of clauses 245 to 263, wherein the controller is configured to receive or determine the heart rate by receiving data from the one or more sensors indicative of a time-averaged heart rate over a measurement period.

265. The apparatus according to any of clauses 245 to 264, wherein the controller is configured to, after controlling the flow generator to maintain the operating flow rate, perform a calibration of the operating flow rate at defined time intervals.

266. The apparatus according to clause 265, wherein the controller is configured to perform the calibration, at each defined time interval of the defined time intervals, by: determining the cardiorespiratory index at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the cardiorespiratory index; determining, at a second flow rate lower than the maintained operating flow rate, the cardiorespiratory index; and operating the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the first flow rate and the second flow rate relative to each other.

267. The apparatus according to clause 266, wherein the controller is configured to perform the calibration by, at the each defined time interval: determining, at a third flow rate higher than the first flow rate, the cardiorespiratory index; determining, at a fourth flow rate lower than the second flow rate, the cardiorespiratory index; and operating the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other. 268. The apparatus according to any of clauses 245 to 267, wherein controller is configured to operate the flow generator to deliver the gas flow to the patient at conditions suitable for provision of high flow therapy.

269. The apparatus according to any of clauses 245 to 268, wherein the controller is configured to operate the flow generator to deliver the gas flow at an operating oxygen concentration level.

270. The apparatus according to clause 269, wherein the controller is configured to: receive or determine, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and if the blood oxygen saturation is determined to be below a stable threshold, operate the flow generator to adjust an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

271. The apparatus according to clause 270, wherein the controller is configured to operate the flow generator such that adjusting the oxygen concentration level is performed prior to progressively applying the plurality of flow rate values.

272. The apparatus according to clause 271, wherein the controller is configured to operate the flow generator such that adjusting the oxygen concentration level is performed simultaneously with progressively applying the plurality of flow rate values.

273. The apparatus according to clause 272, wherein the controller is configured to operate the flow generator such that adjusting the oxygen concentration level is performed second intervals, the second intervals being different to the first intervals.

274. The apparatus according to clause 273, wherein the second intervals are more frequent than the first intervals.

275. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: at intervals, operate the flow generator to progressively apply a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the respiratory rate based at least on the cardiorespiratory index and the cardiorespiratory index received or determined at one or more previous intervals; determine a first stable region corresponding to the status indicating the respiratory rate is stable, the stable region being subsequent to a non-stable region corresponding to the status indicating the respiratory rate is non-stable and/or determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being subsequent to a second non-stable region corresponding to the status indicating the heart rate is non-stable; determine a flow rate value that is within the first stable region and/or the second stable region as the operating flow rate for the gas flow.

276. The apparatus according to clause 275, wherein determining the first stable region comprises determining a first inflection point corresponding to a transition from the first non-stable region to the first stable region, wherein determining the second stable region comprises determining a second inflection point corresponding to a transition from the second stable region to the second non-stable region, and wherein determining the flow rate value comprises determining the flow rate value based on a first flow rate value corresponding to the first inflection point and a second flow rate value corresponding to the second inflection point.

277. The apparatus according to clause 276, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is substantially equidistant from the first flow rate value and the second flow rate value. 278. The apparatus according to clause 277, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the first flow rate value compared to the second flow rate value.

279. The apparatus according to clause 278, wherein determining the flow rate value comprises determining, as the operating flow rate, the flow rate value that is closer to the second flow rate value compared to the first flow rate value.

280. The apparatus according to any of clauses 275 to 279, wherein the controller is configured to: compare the status to one or more thresholds; and wherein determining the flow rate value further comprises determining, as the operating flow rate, the flow rate value that corresponds to the status satisfying the one or more first thresholds.

281. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and perform a process comprising: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; compare the cardiorespiratory index to a threshold range associated with the cardiorespiratory index; and in response to determination of the cardiorespiratory index being outside of the threshold range, operate the flow generator to adjust the flow rate to effect the cardiorespiratory index within the threshold range . 282. The apparatus according to clause 281, wherein the controller is configured to repeat the process at intervals.

283. The apparatus according to clause 281 or 282, wherein the controller is configured to: receive or determine the respiratory rate based on first data from a first sensor; and receive or determine the heart rate based on second data from a second sensor.

284. The apparatus according to clause 281 or 282, wherein the controller is configured to receive or determine the respiratory rate and the heart rate based on data from a single sensor.

285. The apparatus according to any of clauses 281 to 284, wherein the controller is configured to, after effecting the cardiorespiratory index within the threshold range, perform a calibration of the flow rate at defined time intervals.

286. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at a flow rate; and perform a process comprising: at intervals, operate the flow generator to progressively increase or decrease the flow rate by a regular increment or decrement, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and/or a heart rate of the user; at each of the intervals, determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; determine, based on the cardiorespiratory index determined at the intervals, the flow rate that satisfies at least one condition of: a minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the cardiorespiratory index satisfying a threshold, and operating the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

287. The apparatus according to clause 286, wherein the controller is configured such that, in response to determining the cardiorespiratory index failing to satisfy the threshold, repeating the process to operate the flow generator to adjust the flow rate to effect the cardiorespiratory index satisfying the threshold.

288. The apparatus according to clause 286 or 287, wherein the controller is configured to control the flow generator to generate the flow of gases at an initial operating flow rate based on one or more of the following: received patient characteristics; a received clinician-set predefined respiratory rate and/or heart rate; a predetermined respiratory rate and/or heart rate.

289. The apparatus according to any one of clauses 286 to 288, wherein the controller is configured to, after operating the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition, perform, at defined time intervals, a calibration of the flow rate that satisfies the at least one condition.

290. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; operate the flow generator in a first mode comprising: generate the flow of gases at an initial flow rate; increase and/or decrease the initial flow rate by a defined increment or decrement over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, determine, based on data from the one or more sensors, the cardiorespiratory index; determine, based on the cardiorespiratory index determined for the range of flow rates, a desired cardiorespiratory index , and in response to determining the desired cardiorespiratory index , operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index .

291. The apparatus according to clause 290, wherein the controller is configured to determine the desired cardiorespiratory index as the desired cardiorespiratory index, when the cardiorespiratory index that satisfies at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the cardiorespiratory index satisfying a threshold.

292. The apparatus according to clauses 290 or 291, wherein the controller is configured to, after operating the flow generator to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index, perform, at defined time intervals, a calibration of the flow rate corresponding to the desired cardiorespiratory index .

293. The apparatus according to any one of clauses 290 to 292, wherein the controller is configured to monitor the cardiorespiratory index for an efficacy assessment period and determining an efficacy measure based on a change in the cardiorespiratory index over the efficacy assessment period. 294. The apparatus of clause 293, wherein the efficacy measure comprises one or more of the following: an indication that the treatment is sufficient based on the cardiorespiratory index reducing over the efficacy assessment period; an indication that the treatment is insufficient based on the cardiorespiratory index increasing or remaining stable over the efficacy assessment period.

295. An apparatus according to any one of clauses 221 to 294, comprising one or more of the following: a humidifier coupled to an outlet of the flow generator; a memory; a user interface; a communications module; a patient interface.

296. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: the respiratory apparatus according to any one of clauses 221 to 295; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user or respiratory rate of the user, and/or a second patient parameter indicative of a heart rate of the user or a heart rate of the user.

297. The system of clause 296, wherein the sensors comprise one or more of the following: a electromechanical film sensor; a piezoelectric sensor; a non-contact sensor.

298. The system of clause 296 or 297, comprising a humidifier coupled to an outlet of the flow generator.

Claims

2. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

3. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

4. The respiratory therapy system according to claim 2 or the respiratory apparatus according to claim 3, wherein determining the first status comprises performing a first comparison comparing the first patient parameter received or determined at the present interval to the first patient parameter received or determined at one or more previous intervals, and wherein determining the second status comprises performing a second comparison comparing the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals.

5. The respiratory therapy system or apparatus according to claim 4, wherein the first status relates to a degree or amount of change between the first patient parameter received or determined at the present interval to the first patient parameter received or determined at the one or more previous intervals, based on said first comparison, and wherein the second status relates to a degree or amount of change between the second patient parameter received or determined at the present interval to the second patient parameter received or determined at the one or more previous intervals, based on said second comparison.

6. The respiratory therapy system or apparatus according to claim 5, wherein the first status indicates that the respiratory rate is increasing, or is decreasing, or is substantially stable, based on said first comparison, and wherein the second status indicates that the heart rate is increasing, or is decreasing, or is substantially stable, based on said second comparison.

7. The respiratory therapy system or apparatus according to claim 6, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

8. The respiratory therapy system or apparatus according to claim 6 or claim 7, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the first status indicating that the respiratory rate is substantially stable and the second status indicating that the heart rate is substantially stable.

9. The respiratory therapy system or apparatus according to any of claims 2 to 8, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises: comparing the first status to one or more first thresholds; and comparing the second status to one or more second thresholds.

10. The respiratory therapy system or apparatus according to claim 9, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises determining that the operating flow rate be adjusted in response to determination that the first status fails to satisfy the one or more first thresholds and/or the second status fails to satisfy the one or more second thresholds.

11. The respiratory therapy system or apparatus according to claim 7, wherein the step of adjusting the operating flow rate by the increment comprises increasing the operating flow rate by the increment based on the first status indicating that the respiratory rate is decreasing and the second status indicating that the heart rate is substantially stable.

12. The respiratory therapy system or apparatus according to claim 11, wherein the increment is a variable increment, the variable increment based on at least the first status and the second status.

13. The respiratory therapy system or apparatus according to claim 8, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of a previous increment.

14. The respiratory therapy system or apparatus according to any of claims 2 to 13, wherein the controller is further configured to deliver the flow of gases to the user at an operating oxygen concentration level.

15. The respiratory therapy system or apparatus according to claim 14, wherein the controller is further configured to: receive or determine, based on data from the one or more sensors, a third patient parameter indicative of a blood oxygen saturation of the patient; and for delivering the flow of gases and if the blood oxygen saturation is determined to be below a stable threshold, adjust an oxygen concentration level in the flow of gases to the operating oxygen concentration level to improve the blood oxygen saturation to at least the stable threshold.

16. The respiratory therapy system or apparatus according to claim 15, wherein the controller is configured to adjust the oxygen concentration level prior to performing the steps at the intervals.

17. The respiratory therapy system or apparatus according to claim 15, wherein the controller is configured to adjust the oxygen concentration level simultaneously with performing the steps at the intervals.

18. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further i lid second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

19. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; based on the first status indicating that the respiratory rate is stable and the second status indicating that the heart rate is stable, maintaining the operating flow rate, performing an iterative process of continuing to receive or determine said first patient parameter and said second patient parameter, and determine, at further intervals, said first status and said second status; and based on the first status indicating the respiratory rate is no longer stable and/or the second status indicating the heart rate is no longer stable, adjusting the operating flow rate at said further intervals until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

20. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and a controller, wherein the controller is configured to: receive or determine, based on data received from the one or more sensors, the first patient parameter and the second patient parameter; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

21. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to: receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; and control the operating flow rate of the flow generator based on the received or determined first patient parameter and second patient parameter.

22. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to, based on the first status and the second status, adjust the operating flow rate continually until the first status indicates that the respiratory rate is stable and the second status indicates that the heart rate is stable.

23. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, wherein the controller is further configured to, at intervals: progressively apply a plurality of flow rate values for the flow of gases; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determine a first status of the respiratory rate based at least on the first patient parameter and the first patient parameter received or determined at one or more previous intervals; determine a second status of the heart rate based at least on the second patient parameter and the second patient parameter received or determined at the one or more previous intervals; wherein the controller is further configured to: determine a first stable region corresponding to the first status indicating the respiratory rate is stable, the first stable region being subsequent to a first non-stable region corresponding to the first status indicating the respiratory rate is non-stable; determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being before a second non-stable region corresponding to the second status indicating the heart rate is non-stable; and determine a flow rate value that is within the first stable region and the second stable region as an operating flow rate for the flow of gases.

24. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; compare the respiratory rate to a first threshold range associated with the respiratory rate; compare the heart rate to a second threshold range associated with the heart rate; and in response to determination of at least one of the respiratory rate being outside of the first threshold range or the heart rate being outside of the second threshold range, adjust the flow rate to effect the respiratory rate within the first threshold range and the heart rate within the second threshold range.

25. The respiratory apparatus according to claim 24, wherein the controller is configured to repeat the process at intervals.

26. The respiratory apparatus according to claim 24 or 25, wherein, for receiving or determining the respiratory rate and the heart rate, the controller is configured to: receive or determine the respiratory rate based on first data from a first sensor; and receive or determine the heart rate based on second data from a second sensor.

27. The respiratory apparatus according to claim 24 or 25, wherein, for receiving or determining the respiratory rate and the heart rate, the controller is configured to receive or determine the respiratory rate and the heart rate based on data from a single sensor.

28. The respiratory apparatus according to any of claims 24 to 27, wherein the controller is further configured to, after the respiratory rate is effected within the first threshold range and the heart rate is effected within the second threshold range, perform a calibration of the flow rate at defined time intervals.

29. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator to generate the flow of gases at a flow rate, the controller being further configured to perform a process to: at intervals, progressively increase the flow rate by a regular increment, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine, based on the respiratory rate and the heart rate received or determined at the intervals, the flow rate that satisfies at least one condition of: a minimum respiratory rate, or a minimum heart rate, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold, and control the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

30. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user; and a controller configured to control operation of the flow generator, the controller being further configured to: continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; operate the flow generator in a first mode to: generate the flow of gases at an initial flow rate; increase the initial flow rate by a defined increment over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is to be delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, receive or determine, based on data from the one or more sensors, the respiratory rate and the heart rate; determine, based on the respiratory rate and the heart rate received or determined for the range of flow rates, a desired respiratory rate and a desired heart rate, and in response to the desired respiratory rate and the desired heart rate being determined, operate the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate.

31. The respiratory apparatus according to claim 30, wherein the controller is configured, for determining the desired respiratory rate and the desired heart rate, to determine, as the desired respiratory rate and the desired heart rate, the respiratory rate and the heart rate that satisfy at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum respiratory rate, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum heart rate, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the respiratory rate satisfying a first threshold and the heart rate satisfying a second threshold.

32. The respiratory apparatus according to claim 30 or 31, wherein the controller is further configured to, after generating the flow of gases at the flow rate corresponding to the desired respiratory rate and the desired heart rate, perform, at defined time intervals, a calibration of the flow rate corresponding to the desired respiratory rate and the desired heart rate.

33. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, and further configured to, at intervals, perform the steps of: receiving or determining, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the user and a second patient parameter indicative of a heart rate of the user; determining a first status of the respiratory rate based at least on said first patient parameter and the first patient parameter received or determined at one or more previous intervals; determining a second status of the heart rate based at least on said second patient parameter and the second patient parameter received or determined at the one or more previous intervals; determining whether to adjust or maintain the operating flow rate based on the first status and the second status, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, wherein the controller is further configured to repeat the steps throughout a therapy session for the respiratory therapy to adjust or maintain the operating flow rate throughout the therapy session.

34. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, perform the steps of: receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indictive of a heart rate of the patient; determining a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter determining whether to adjust or maintain the operating flow rate based on the cardiorespiratory index ; and based on determining that said operating flow rate be adjusted, operate the flow controller to adjust the operating flow rate depending on the cardiorespiratory index, and based on determining that said operating flow rate be maintained, operate the flow controller to maintain the operating flow rate at the present operating flow rate.

35. The apparatus according to claim 34, wherein the cardiorespiratory index is determined using a predefined first patient parameter and a predefined second patient parameter.

36. The apparatus according to claim 35, wherein the predefined first patient parameter and/or the predefined second patient parameter is determined based on one or more of the following: received patient characteristics; a received clinician-set respiratory rate; a clinicianset first patient parameter; a clinician-set heart rate; a clinician-set second patient parameter; historical patient data; historical data relating to other patients; a default value.

37. The apparatus according to claim 35 or 36, wherein the cardiorespiratory index is based on a difference between the received or determined first patient parameter and the predefined first patient parameter and a difference between the received or determined second patient parameter and the predefined second patient parameter.

38. The apparatus according to any one of claims 34 to 37, wherein operating the flow generator to adjust the operating flow rate comprises operating the flow controller to adjust the operating flow rate to reduce the cardiorespiratory index to a minimum or within a predefined cardiorespiratory index threshold.

39. The apparatus of claim 38, wherein operating the flow generator to adjust the operating flow rate comprises operating the flow generator to increase or decrease the operating flow rate by one or more increments dependent on the cardiorespiratory index.

40. The apparatus of claim 39, wherein the increment is a variable increment based on the cardiorespiratory index.

41. The apparatus according to any one of claims 34 to 40, wherein determining whether to adjust or maintain the operating flow rate is based on the cardiorespiratory index being outside a predefined cardiorespiratory index threshold.

42. The apparatus of any one of claims 34 to 41, wherein the controller is configured to signal a warning responsive to the received or determined first patient parameter being outside a predefined first patient parameter range and/or the received or determined second patient parameter being outside a predefined second patient parameter range.

43. The apparatus according to any one of claims 34 to 42, wherein the controller is configured to operate the flow generator to deliver the gas flow to the patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more of the following: received patient characteristics; a received clinician-set operating flow rate; a predetermined operating flow rate in a midrange between a minimum operating flow rate and a maximum operating flow rate; a predefined or default operating flow rate stored in a memory.

44. The apparatus according to any one of claims 34 to 43, the controller configured to operate the flow generator to, after maintaining the operating flow rate, perform a calibration of the operating flow rate at defined time intervals.

45. The apparatus according to claim 44, wherein the controller is configured to perform the calibration at each defined time interval of the defined time intervals, by: determining the cardiorespiratory index at the maintained operating flow rate; determining, at a first flow rate higher than the maintained operating flow rate, the cardiorespiratory index; determining, at a second flow rate lower than the maintained operating flow rate, the cardiorespiratory index; and operating the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, at the first flow rate and at the second flow rate relative to each other.

46. The apparatus according to claim 45, wherein the controller is configured to perform the calibration at the each defined time interval, by: determining, at a third flow rate higher than the first flow rate, the cardiorespiratory index; determining, at a fourth flow rate lower than the second flow rate, the cardiorespiratory index; and operate the flow generator to adjust or maintain the maintained operating flow rate depending on a comparison of the cardiorespiratory index at the maintained operating flow rate, the third flow rate and the fourth flow rate relative to each other.

47. The apparatus according to any one of claims 34 to 46, wherein the controller is configured to base the cardiorespiratory index on a time-averaged first patient parameter over a first measurement period and a time-averaged second patient parameter over a second measurement period.

48. The apparatus according to any one of claims 34 to 47, wherein the controller is configured to: determine a status of the patient based at least on the cardiorespiratory index, wherein determining the status comprises performing a comparison comparing the cardiorespiratory index determined at the present interval to the cardiorespiratory index determined at one or more previous intervals.

49. The apparatus according to claim 48, wherein the status indicates that the respiratory rate and/or the heart rate is increasing, or is decreasing, or is substantially stable, based on said comparison.

50. The apparatus according to claim 49, wherein the controller is configured to determine whether to adjust the operating flow rate by determining that the operating flow rate be adjusted based on the status indicating that one of the respiratory rate or the heart rate is decreasing and that the other of the heart rate or the respiratory rate is substantially stable.

51. The apparatus according to any one of claims 34 to 50, wherein the controller is configured to operate the flow generator over a therapy session or a predefined period.

52. The apparatus according to any one of claims 34 to 51, wherein the controller is configured to: receive or determine, based on data from one or more sensors, a third patient parameter indicative of a blood oxygen saturation level of the patient; and if the blood oxygen saturation level is determined to be below a stable threshold, operate the flow generator adjust an oxygen concentration level in the gas flow to the operating oxygen concentration level to improve the blood oxygen saturation level to at least the stable threshold.

53. The apparatus according to claim 52, wherein the controller is configured to operate the flow generator to adjust the blood oxygen saturation level prior to performing the steps at the intervals.

54. The apparatus according to claim 52, wherein the controller is configured to operate the flow generator to adjust the blood oxygen saturation level simultaneously with performing the steps at the intervals.

55. The apparatus according to any one of claims 34 to 54, wherein the controller is configured to determine whether to adjust or maintain the operating flow rate by determining whether the cardiorespiratory index corresponds to a local minimum respiratory rate and/or a local minimum heart rate.

56. The apparatus according to claim 55, wherein the controller is configured to operate the flow generator to adjust the operating flow rate depending on the cardiorespiratory index to correspond with a local minimum for the respiratory rate or a local minimum for the heart rate.

57. The apparatus according to any one of claim 34 to 56, wherein the controller is configured to adjust the operating flow rate by adjusting the operating flow rate to adjust the cardiorespiratory index to a local minimum.

58. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, operate the flow generator to progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receive or determine, based on data received from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the patient based at least on said cardiorespiratory index and the cardiorespiratory index determined at one or more previous intervals ; based on the status indicating the respiratory rate and/or the heart rate is stable, operate the flow generator to maintain the operating flow rate, and perform an iterative process of continuing to receive or determine said respiratory rate, said heart rate and cardiorespiratory index, and determine, at further intervals, said status; and based on the status indicating the respiratory rate and/or the heart rate is no longer stable, operate the flow controller to adjust the operating flow rate at said further intervals until the status indicates that the respiratory rate and/or the heart rate is stable.

59. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: at intervals, operate the flow generator to progressively apply a plurality of flow rate values for the gas flow; at each of the plurality of flow rate values, receive or determine, based on data from one or more sensors, a first patient parameter indicative of a respiratory rate of the patient and a second patient parameter indicative of a heart rate of the patient; determine a cardiorespiratory index based on the received or determined first patient parameter and the received or determined second patient parameter; determine a status of the respiratory rate based at least on the cardiorespiratory index and the cardiorespiratory index received or determined at one or more previous intervals; determine a first stable region corresponding to the status indicating the respiratory rate is stable, the stable region being subsequent to a non-stable region corresponding to the status indicating the respiratory rate is non-stable and/or determine a second stable region corresponding to the second status indicating the heart rate is stable, the second stable region being subsequent to a second non-stable region corresponding to the status indicating the heart rate is non-stable; determine a flow rate value that is within the first stable region and/or the second stable region as the operating flow rate for the gas flow.

60. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and perform a process comprising: receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; compare the cardiorespiratory index to a threshold range associated with the cardiorespiratory index; and in response to determination of the cardiorespiratory index being outside of the threshold range, operate the flow generator to adjust the flow rate to effect the cardiorespiratory index within the threshold range .

61. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at a flow rate; and perform a process comprising: at intervals, operate the flow generator to progressively increase or decrease the flow rate by a regular increment or decrement, at each of the intervals, receive or determine, based on data from one or more sensors, a respiratory rate of the user and/or a heart rate of the user; at each of the intervals, determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; determine, based on the cardiorespiratory index determined at the intervals, the flow rate that satisfies at least one condition of: a minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, or a second inflection point associated with the heart rate, or the cardiorespiratory index satisfying a threshold, and operating the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition.

62. The apparatus according to claim 61, wherein the controller is configured such that, in response to determining the cardiorespiratory index failing to satisfy the threshold, repeating the process to operate the flow generator to adjust the flow rate to effect the cardiorespiratory index satisfying the threshold.

63. The apparatus according to claim 61 or 62, wherein the controller is configured to control the flow generator to generate the flow of gases at an initial operating flow rate based on one or more of the following: received patient characteristics; a received clinician-set predefined respiratory rate and/or heart rate; a predetermined respiratory rate and/or heart rate.

64. The apparatus according to any one of claims 61 to 63, wherein the controller is configured to, after operating the flow generator to generate the flow of gases at the flow rate that satisfies the at least one condition, perform, at defined time intervals, a calibration of the flow rate that satisfies the at least one condition.

65. A respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller configured to control operation of the flow generator, the controller being further configured to: operate the flow generator to deliver a gas flow to the patient via a patient interface at an operating flow rate; and continuously receive or determine, based on data from one or more sensors, a respiratory rate of the user and a heart rate of the user; determine a cardiorespiratory index based on the received or determined respiratory rate and the received or determined heart rate; operate the flow generator in a first mode comprising: generate the flow of gases at an initial flow rate; increase and/or decrease the initial flow rate by a defined increment or decrement over a range of flow rates, wherein the flow of gases at each flow rate over the range of flow rates is delivered to the user for a predefined time interval; for the each flow rate for the predefined time interval, determine, based on data from the one or more sensors, the cardiorespiratory index; determine, based on the cardiorespiratory index determined for the range of flow rates, a desired cardiorespiratory index , and in response to determining the desired cardiorespiratory index, operating the flow generator in a second mode to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index .

66. The apparatus according to claim 65, wherein the controller is configured to determine the desired cardiorespiratory index as the desired cardiorespiratory index, when the cardiorespiratory index that satisfies at least one condition of: a minimum respiratory rate, and the heart rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a minimum heart rate, and the respiratory rate corresponding to the flow rate that is associated with the minimum cardiorespiratory index, or a first inflection point associated with the respiratory rate, and the heart rate corresponding to the flow rate that is associated with the first inflection point, or a second inflection point associated with the heart rate, and the respiratory rate corresponding to the flow rate that is associated with the second inflection point, or the cardiorespiratory index satisfying a threshold.

67. The apparatus according to claims 65 or 66, wherein the controller is configured to, after operating the flow generator to generate the flow of gases at the flow rate corresponding to the desired cardiorespiratory index, perform, at defined time intervals, a calibration of the flow rate corresponding to the desired cardiorespiratory index.

68. The apparatus according to any one of claims 65 to 67, wherein the controller is configured to monitor the cardiorespiratory index for an efficacy assessment period and determining an efficacy measure based on a change in the cardiorespiratory index over the efficacy assessment period.

69. The apparatus of claim 68, wherein the efficacy measure comprises one or more of the following: an indication that the treatment is sufficient based on the cardiorespiratory index reducing over the efficacy assessment period; an indication that the treatment is insufficient based on the cardiorespiratory index increasing or remaining stable over the efficacy assessment period.

70. An apparatus according to any one of claims 65 to 69, comprising one or more of the following: a humidifier coupled to an outlet of the flow generator; a memory; a user interface; a communications module; a patient interface.

71. A respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: the respiratory apparatus according to any one of claims 3 to 17, 19 and 21 to 70; one or more sensors configured to measure a first patient parameter indicative of a respiratory rate of the user or respiratory rate of the user, and/or a second patient parameter indicative of a heart rate of the user or a heart rate of the user.

72. The system of claim 71, wherein the sensors comprise one or more of the following: a electromechanical film sensor; a piezoelectric sensor; a non-contact sensor.