CN112569440B - Dynamic calibration device for zero position of flow sensor of anesthesia machine and dynamic calibration method thereof - Google Patents

Abstract

The invention discloses a dynamic calibration device for the zero position of a flow sensor of an anesthesia machine and a dynamic calibration method thereof. The expiratory flow sensor can be zeroed during inhalation and the inspiratory flow sensor can be zeroed during exhalation. It realizes real-time zero calibration when the anesthesia machine is working without stopping the machine for zero calibration; the inspiratory and expiratory flow sensor zero calibration can be completed in one ventilation cycle. Inhalation and exhalation are performed alternately, and zero calibration and measurement are also performed alternately. After each zero calibration, it can be used immediately for the next flow measurement. Even if zero drift occurs during use, it can be eliminated immediately, truly achieving It achieves real-time, non-stop and dynamic zero calibration; and the zero calibration is carried out automatically without manual operation, eliminating zero calibration errors caused by human factors.

Description

Dynamic calibration device for zero position of flow sensor of anesthesia machine and dynamic calibration method thereof

Technical field

The invention relates to an anesthesia machine, and in particular to a dynamic calibration device for the zero position of a flow sensor of the anesthesia machine and a dynamic calibration method thereof.

Background technique

The anesthesia machine is a life support system used in hospital operating rooms to provide general anesthesia to surgical patients. Its main function is to provide respiratory management, oxygen supply, and inhalation of anesthetics for the patient. The anesthesia machine ventilates the patient at a certain frequency and measures the volume of gas the patient inhales (hereinafter referred to as the inhalation volume) and the volume of gas discharged (hereinafter referred to as the tidal volume). In actual use, inhaled volume and tidal volume are important clinical parameters.

Both inspiratory volume and tidal volume are measured via flow sensors. When the patient inhales, the actual measured value of the inspiratory flow sensor is integrated to obtain the inhalation volume; when the patient exhales, the actual measured value of the expiratory flow sensor is integrated to obtain the tidal volume. It can be seen that the accuracy of inhalation volume and tidal volume is determined by the measurement accuracy of the flow sensor. Normally, the flow sensor can achieve higher accuracy requirements after calibration. However, after being used for a period of time, the flow sensor will drift to zero, causing a large error in the measured tidal volume. At this time, the flow sensor must be inspected. Zero calibration (hereinafter referred to as zero calibration), and zero calibration must be performed when the flow sensor is blocked, so the original ventilation must be stopped before it can be performed. Under normal circumstances, the anesthesia machine cannot be stopped midway after being connected to the patient and starting ventilation, otherwise the patient will suffocate. Therefore, the zero calibration of the flow sensor can only be performed in standby, which can only solve the problem of zero drift before use. If zero drift occurs due to various factors in actual use, nothing can be done.

Contents of the invention

In view of the problems existing in the prior art, the present invention provides a dynamic calibration device for the zero position of the flow sensor of an anesthesia machine and a dynamic calibration method thereof. The air flow sensor performs zero calibration to achieve real-time zero calibration while the anesthesia machine is working without stopping the machine for zero calibration. It is calibrated to zero in every breathing cycle, which can overcome zero drift during use. Moreover, zero calibration is performed automatically without manual operation, eliminating zero calibration errors caused by human factors.

The technical solution of the present invention is: a dynamic calibration device for the zero position of the flow sensor of an anesthesia machine, including an inhalation end bellows and an expiration end bellows;

One end of the inhalation end bellows and the expiration end bellows are connected through each other, and a patient's breathing port is provided at the connection;

The other end of the suction end bellows is connected to the air outlet of the suction end one-way valve through a first connecting pipeline, and the air inlet of the suction end one-way valve is connected to the patient circuit. The first connecting pipeline is provided with a suction air flow sensor;

The other end of the inspiratory end bellows is connected to the air inlet of the expiratory end one-way valve through a second connecting pipe, and the air outlet of the exhaled end one-way valve is connected to the patient circuit. The second connecting pipe is provided with an exhalation valve. air flow sensor;

The inspiratory flow sensor is connected to the microcontroller through a first digital-to-analog converter;

The exhalation flow sensor is connected to the microcontroller through a second digital-to-analog converter.

The present invention also provides a dynamic calibration method for the zero position of the flow sensor of the anesthesia machine implemented by the dynamic calibration device for the zero position of the flow sensor of the anesthesia machine. During inhalation, the flow rate flowing through the expiratory flow sensor is 0 ; During exhalation, the flow rate flowing through the inspiratory flow sensor is 0; during inhalation, the expiratory flow sensor is zeroed, and during exhalation, the inspiratory flow sensor is zeroed.

Further, the exhalation flow sensor is zero-calibrated during inhalation. The specific steps are as follows:

Step 1. When the anesthesia machine inhales, the signal measured by the expiratory flow sensor is converted into a digital signal through the second digital-to-analog converter and sent to the microcontroller. The microcontroller processes the digital signal to obtain the flow rate of the expiratory flow sensor. AD value at zero time;

Step 2: Predict the AD value of the expiratory flow sensor when the flow rate is zero obtained in step 1. If the difference from the zero AD value of the last expiratory flow sensor is within the threshold range, the calibration is considered to be correct. Zero is valid, and the zero AD value of the expiratory flow sensor will be used as the new zero AD value of the expiratory flow sensor;

Step 3: When subsequently measuring the expiratory flow rate, subtract the new expiratory flow sensor zero AD value obtained in step 2 from the actual measured AD value of the expiratory flow sensor to obtain a Δ value;

Step 4: Calculate the actual expiratory flow value according to the calibration curve of the expiratory flow sensor; the calibration curve is the corresponding relationship curve between the Δ value and the flow value.

Further, the inspiratory flow sensor is zero-calibrated during exhalation. The specific steps are as follows:

Step 1. When the anesthesia machine exhales, the signal measured by the inspiratory flow sensor is converted into a digital signal through the first digital-to-analog converter and transmitted to the microcontroller. The microcontroller processes the digital signal to obtain the flow rate of the inspiratory flow sensor. AD value at zero time;

Step 2: Predict the AD value of the inspiratory flow sensor obtained in step 1 when the flow rate is zero. If the difference from the previous zero AD value of the inspiratory flow sensor is within the threshold range, the calibration is considered to be correct. Zero is valid, and the zero AD value of the inspiratory flow sensor will be used as the new zero AD value of the inspiratory flow sensor;

Step 3. When subsequently measuring the inspiratory flow rate, subtract the new inspiratory flow sensor zero AD value obtained in step 2 from the actual measured AD value of the inspiratory flow sensor to obtain a Δ value;

Step 4: Calculate the actual inspiratory flow value according to the calibration curve of the inspiratory flow sensor; the calibration curve is the corresponding relationship curve between the Δ value and the flow value.

Further, the threshold value is ±100AD value.

Furthermore, during the dynamic zero calibration process, the AD value of the zero flow rate is predicted. If the difference from the zero AD value of the last zero calibration exceeds the threshold, the processing result of this zero calibration is abandoned and the zero position is not changed. Update, and the alarm prompts that the automatic zero calibration of the flow sensor failed.

Furthermore, the inhalation one-way valve and the exhalation one-way valve are self-checked when the machine is turned on. If reverse air leakage is detected, an alarm will be issued to remind the user to check the one-way valve, and for the one-way valve with reverse air leakage Automatically shield the dynamic zeroing process during actual work.

The beneficial effects of the present invention are: providing a dynamic calibration device for the zero position of the flow sensor of an anesthesia machine and a dynamic calibration method thereof, which can zero-calibrate the expiratory flow sensor during inhalation, and calibrate the inspiratory flow sensor during exhalation. Perform zero calibration to achieve real-time zero calibration while the anesthesia machine is working without stopping the machine for zero calibration.

Zero calibration of the inspiratory and expiratory flow sensors can be completed in one ventilation cycle. Inhalation and exhalation are performed alternately, and zero calibration and measurement are also performed alternately. After each zero calibration, it can be used immediately for the next flow measurement. Even if zero drift occurs during use, it can be eliminated immediately, truly achieving This enables real-time, non-stop, dynamic zero calibration.

Moreover, zero calibration is performed automatically without manual operation, eliminating zero calibration errors caused by human factors.

Description of the drawings

Figure 1 is a schematic structural diagram of the dynamic calibration device for the zero position of the flow sensor of the anesthesia machine.

In the picture: 1 is the inspiratory flow sensor, 2 is the expiratory flow sensor, 3 is the inspiratory end one-way valve, 4 is the expiratory end one-way valve, 5 is the inspiratory end bellows, 6 is the expiratory end bellows. , 7 is the patient's breathing port, 8 is the first digital-to-analog converter, and 9 is the second digital-to-analog converter.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Figure 1 is a schematic diagram of the patient side of anesthesia machine ventilation. When the anesthesia machine ventilation is working, during the inhalation stage, the gas flows from the patient circuit to the patient. Due to the role of CV2, the airflow will not go through the B2 path, but can only flow into the patient from the B1 path, so the airflow direction during inhalation is: Patient circuit → CV1 → SE1 → B1 → Patient. At this time, SE1 can measure the flow rate. By integrating this flow rate, the inhalation volume is obtained. There is no flow through SE2, so theoretically the flow rate measured by SE2 is 0; during exhalation In this stage, the gas flows from the patient to the patient circuit. Because of the function of CV1, the air flow will not go through the B1 path, but can only flow into the patient from the B2 path. Therefore, when exhaling, the air flow direction is: patient → B2 → SE2 → CV2 → patient circuit , at this time SE2 can measure the flow, and integrate this flow to get the tidal volume. There is no flow flowing through SE1, so theoretically the flow measured by SE1 is 0.

Among them: SE1 is the inspiratory flow sensor 1, SE2 is the expiratory flow sensor 2, CV1 is the inspiratory end one-way valve 3, CV2 is the expiratory end one-way valve 4.

According to the above principle, it can be seen that during inhalation, the flow rate flowing through SE2 is 0, and during exhalation, the flow rate flowing through SE1 is 0. Therefore, the expiratory flow sensor can be zeroed during inhalation. Zero the inspiratory flow sensor.

When the anesthesia machine inhales, the signal measured by SE2 is converted into a digital signal through A/D and sent to the microcontroller. The microcontroller processes the digital signal to obtain the AD value of SE2 when the flow rate is zero, and performs the AD value on this Prejudgment, if the difference from the last SE2 zero AD value is within a reasonable range (±100AD value), this zero calibration will be considered valid, and this AD value will be used as the new SE2 zero AD value. When subsequently measuring expiratory flow, subtract the SE2 zero AD value from the SE2 measured AD value to obtain a Δ value, and then calculate the actual value based on the calibration curve of SE2 (the calibration curve is the corresponding relationship curve between the Δ value and the flow value). expiratory flow value. The above processing process realizes the dynamic zero calibration of SE2 during the inhalation process.

When the anesthesia machine exhales, the signal measured by SE1 is converted into a digital signal through A/D and sent to the microcontroller. The microcontroller processes the digital signal to obtain the AD value of SE1 when the flow rate is zero, and performs the AD value on this Prejudgment, if the difference from the last SE1 zero AD value is within a reasonable range (±100AD value), this zero calibration will be considered valid, and this AD value will be used as the new SE1 zero AD value. When subsequently measuring the inspiratory flow rate, subtract the zero AD value of SE1 from the actual measured AD value of SE1 to obtain a Δ value, and then calculate the actual inspiratory flow value based on the calibration curve of SE1. The above processing process realizes the dynamic zero calibration of SE1 during exhalation.

In order to ensure the effectiveness and accuracy of dynamic zero calibration and prevent zero calibration distortion caused by reverse leakage of the one-way valve, the following processing can be done: ① During the dynamic zero calibration process, predict the AD value of the zero flow rate. If the zero AD value of the last zero calibration deviates too much, the processing result of this zero calibration will be abandoned, the zero position will not be updated, and an alarm will prompt that the automatic zero calibration of the flow sensor failed. ② Carry out self-check on the one-way valve when starting up. If reverse air leakage is detected, an alarm will be issued to remind the user to check the one-way valve. For the one-way valve with reverse air leakage, the dynamic zero calibration will be automatically blocked during actual operation. process to avoid causing greater errors.

It can be seen from the above that the zero calibration of the inspiratory and expiratory flow sensors can be completed in one ventilation cycle. Inhalation and exhalation are performed alternately, and zero calibration and measurement are also performed alternately. After each zero calibration, it can be used immediately for the next flow measurement. Even if zero drift occurs during use, it can be eliminated immediately, truly achieving This enables real-time, non-stop, dynamic zero calibration.

Using the above-mentioned dynamic calibration device for the zero position of the flow sensor of the anesthesia machine and its dynamic calibration method, the expiratory flow sensor can be zeroed during inhalation, and the inspiratory flow sensor can be zeroed during exhalation, thus achieving a smooth operation of the anesthesia machine. Zero calibration can be performed in real time while working without shutting down the machine. It is calibrated to zero in every breathing cycle, which can overcome zero drift during use. Moreover, zero calibration is performed automatically without manual operation, eliminating zero calibration errors caused by human factors.

The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications can also be made. should be regarded as the protection scope of the present invention.

Claims (4)

1. A dynamic calibration method for the zero position of the flow sensor of an anesthesia machine, which is characterized by: zeroing the expiratory flow sensor during inhalation, and zeroing the inspiratory flow sensor during exhalation; When the anesthesia machine is working for ventilation, during the inhalation stage, the gas flows from the patient circuit to the patient. Due to the function of the one-way valve at the expiration end, the air flow will not go through the bellows at the expiration end, but can only flow from the bellows at the inhalation end. All the way flows into the patient, so the airflow direction during inhalation is: patient circuit → inspiratory end one-way valve → inspiratory flow sensor → inspiratory end bellows → patient. At this time, the inspiratory flow sensor can measure the flow rate and use this flow rate The inhalation volume is obtained by integrating. There is no flow through the expiratory flow sensor, so the flow measured by the expiratory flow sensor is 0; during the expiration phase, the gas flows from the patient to the patient circuit because of the function of the one-way valve at the inhalation end. , the airflow will not go through the inspiratory end bellows, but can only flow into the patient from the expiratory end bellows, so when exhaling, the airflow direction is: patient → expiratory end bellows → expiratory flow sensor → exhalation End one-way valve → patient circuit. At this time, the expiratory flow sensor can measure the flow. By integrating this flow, the tidal volume is obtained. There is no flow through the inspiratory flow sensor, so the flow measured by the inspiratory flow sensor is 0. ; The specific steps for zeroing the expiratory flow sensor during inhalation are as follows: Step 1. When the anesthesia machine inhales, the signal measured by the expiratory flow sensor is converted into a digital signal through the second digital-to-analog converter and sent to the microcontroller. The microcontroller processes the digital signal to obtain the flow rate of the expiratory flow sensor. AD value at zero time; Step 2: Predict the AD value of the expiratory flow sensor when the flow rate is zero obtained in step 1. If the difference from the zero AD value of the last expiratory flow sensor is within the threshold range, the calibration is considered to be correct. Zero is valid, and the zero AD value of the expiratory flow sensor will be used as the new zero AD value of the expiratory flow sensor; Step 3: When subsequently measuring the expiratory flow rate, subtract the new expiratory flow sensor zero AD value obtained in step 2 from the actual measured AD value of the expiratory flow sensor to obtain a Δ value; Step 4: Calculate the actual expiratory flow value according to the calibration curve of the expiratory flow sensor; the calibration curve is the corresponding relationship curve between the Δ value and the flow value; The specific steps for zeroing the inspiratory flow sensor during exhalation are as follows: Step 1. When the anesthesia machine exhales, the signal measured by the inspiratory flow sensor is converted into a digital signal through the first digital-to-analog converter and transmitted to the microcontroller. The microcontroller processes the digital signal to obtain the flow rate of the inspiratory flow sensor. AD value at zero time; Step 2: Predict the AD value of the inspiratory flow sensor obtained in step 1 when the flow rate is zero. If the difference from the previous zero AD value of the inspiratory flow sensor is within the threshold range, the calibration is considered to be correct. Zero is valid, and the zero AD value of the inspiratory flow sensor will be used as the new zero AD value of the inspiratory flow sensor; Step 3. When subsequently measuring the inspiratory flow rate, subtract the new inspiratory flow sensor zero AD value obtained in step 2 from the actual measured AD value of the inspiratory flow sensor to obtain a Δ value; Step 4: Calculate the actual inspiratory flow value according to the calibration curve of the inspiratory flow sensor; the calibration curve is the corresponding relationship curve between the Δ value and the flow value. 2. The dynamic calibration method for the zero position of the flow sensor of an anesthesia machine according to claim 1, characterized in that: the threshold value is ±100AD value. 3. The dynamic calibration method for the zero position of the flow sensor of an anesthesia machine according to claim 1, characterized in that: during the dynamic zero calibration process, the AD value of the zero flow rate is pre-judged. If it is different from the zero value of the last zero calibration, If the difference between the AD values exceeds the threshold, the zero calibration result will be abandoned, the zero position will not be updated, and an alarm will appear indicating that the automatic zero calibration of the flow sensor failed. 4. The dynamic calibration method for the zero position of the flow sensor of an anesthesia machine according to claim 1, characterized in that: when starting up, the inhalation one-way valve and the exhalation one-way valve are self-checked. If a reverse direction is detected, If there is air leakage, an alarm will be issued to remind the user to check the one-way valve, and for the one-way valve with reverse air leakage, the dynamic zeroing process will be automatically blocked during actual operation.