JP5360897B2 - Anesthesia system and method of operating anesthesia system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anesthetic system that compensates for loss of ventilation quantity when the measured-rate control is used. <P>SOLUTION: The anesthetic system 1 includes: a bellows position sensor 6d which measures the distance of downward movements of the bellows top 6c from the ceiling of a chamber 6b which encases a bellows 6a; a memory to store the data of the movement quantity of the bellows top and a functional sectional area resulting from dividing a prescribed injection quantity of drive gas by this movement quantity of the bellows top 6c in the form of a data table or an approximate calculation formula referred to by the control software, when the prescribed quantity of drive gas is injected into the space between the bellows 6a and the chamber 6b beforehand; a control part 7 to determine the system compliance including gas leak quantities, based on the data of the prescribed movement quantity and functional sectional area and changes in the inner pressure of the respiratory circuit arising from sending the drive gas before the system is connected to the respiratory tract of a patient; and a drive gas generator 5 to supply the bellows-in chamber 6 with the drive gas where the ventilation quantity loss having arisen from the system compliance is added. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an anesthesia system and a method for operating an anesthesia system.

  Conventionally, anesthesia ventilators responsible for patient respiratory management in general anesthesia are roughly classified into two types: (1) a gas driven bellows-in-chamber ventilator and (2) an electrically driven piston ventilator. The thing of patent document 1 is proposed as a prior art of a bellows-in-chamber type ventilator.

The former controls the amount of driving gas, while the latter controls the moving distance of the piston.
Although each has its characteristics, the compensation method for the tidal volume loss caused by the influence of the pressure-volume compliance of the respiratory circuit, hereinafter referred to as “system compliance” in accordance with clinical practice, is greatly different.
JP 2000-325480 A

  By the way, the bellows-in chamber, which is mainly used as an anesthesia ventilator today, is a type called an inverted type in which the bellows rises in the expiratory phase. Function (2) Even if a leak in the respiratory circuit or gas shortage occurs, it does not immediately become abnormal ventilation operation, and it is easy to detect the state, (3) The bellows rises passively in response to patient exhalation Therefore, the synchronism with the patient is excellent. (4) Since the bellows is driven by the driving gas, it has an advantage of being able to cope with both metered amount control and pressure control without difficulty. On the other hand, the bellows originally does not have a stable cross-sectional area, so that the driving amount cannot be measured accurately. Therefore, there has been a limit to the measurement of system compliance without relying on other means such as a differential pressure detection type flow sensor having a limit in accuracy. For this reason, there has been a problem that it is difficult to compensate with sufficient accuracy the loss of ventilation due to system compliance at the time of metered control.

  On the other hand, in the piston type ventilator, the driving amount = the cross-sectional area × the moving distance, and the measurement of the system compliance is relatively easy and the reliability is high. However, the piston type ventilator is usually driven by an electric motor, and (1) there is no synchrony with the patient exhalation, and (2) it works normally even if there is a leak in the breathing circuit. There are drawbacks such as generating a large negative pressure due to gas shortage, and (3) being unsuitable for sub pressure control that requires agile control of the flow rate because the mass of the piston is large.

  Accordingly, the present invention has been made in view of the above problems, and even when a bellows-in-chamber type ventilator is used, a loss of ventilation due to system compliance at the time of metered amount control is compensated with sufficient accuracy. An object of the present invention is to provide an anesthesia system and a method for operating the anesthesia system.

In order to solve the above problems, an anesthesia system of the present invention is an anesthesia system including a circulation type breathing circuit including a fresh gas on-off valve that prevents a fresh gas steady flow from being added to an intake air amount and a bellows-in chamber. Measuring means for measuring the distance that the bellows top moves downward from the ceiling of the chamber surrounding the bellows;
Control software having a functional cross-sectional area obtained by injecting a predetermined amount of driving gas into the space between the bellows and the chamber, and moving the bellows top and dividing the predetermined amount of driving gas by the moving amount of the bellows top As a data table or approximate calculation formula that can be referred to, memory stored in advance prior to factory shipment, data referenced therefrom, and changes in breathing circuit internal pressure caused by sending drive gas before connecting to the patient airway And calculating means for obtaining a system compliance including a leak amount, and a supply means for supplying a driving gas to which the ventilation amount lost by the system compliance including the leak amount is added in advance to the bellows-in chamber after being connected to the patient airway. .

  According to the present invention, even if a bellows-in-chamber type ventilator is used by sending in advance a part of the ventilation amount lost due to system compliance including the leak amount, the bellows-in-chamber type ventilator is used. While maintaining the advantage of the ventilator, it is possible to compensate for the loss of ventilation volume at the time of metered volume control with sufficient accuracy.

Further, in the above invention, the computing means is a bellows top when the inside of the chamber is pressurized with a driving gas with the patient connection end closed before being connected to the patient airway, and the breathing circuit internal pressure is stabilized at a constant pressure Ppl. The amount of movement is DB, and the pressure when the pressure is released and the bellows is stable in contact with the ceiling of the chamber is PEEP, and the value corresponding to the DB is referred to from the data table or the approximate calculation formula. When the bellows drive amount and the functional cross-sectional area are VB and SB, the system compliance CS including the leak amount is obtained by the following formula, and this is particularly called the initial system compliance CSi.
CSi = VB / (Ppl-PEEP) = (SB × DB) / (Ppl-PEEP)
When the supply means connects the patient connection end to the patient airway and drives the bellows-in chamber with the drive gas VB, if the intake plateau pressure Ppl and the end-expiratory pressure PEEP are assumed, the difference between Ppl and PEEP is given to the CSi. It is supplied as the amount of driving gas added by the multiplied amount, CSi × (Ppl-PEEP).

  In the above invention, the calculating means continues the time for maintaining the breathing circuit internal pressure Ppl when the inside of the chamber is pressurized with the driving gas VB for a predetermined time, and further after the expansion of the breathing circuit is completed for a predetermined time. The T (second) pressurization is continued, and the leak amount VL = SB × ΔDB × 60 / T per minute of the breathing circuit can be obtained and displayed from the change amount ΔDB of the bellows top movement amount DB during that time.

  The operation method of the anesthesia system according to the present invention is an operation method of the anesthesia system including a circulation type breathing circuit including a fresh gas on-off valve that prevents a fresh gas steady flow from being added to the intake amount and a bellows-in chamber. A measuring step of measuring the distance by which the bellows top moves downward from the ceiling of the chamber enclosing the bellows by a measuring means; a functional cross-sectional area obtained by dividing the predetermined amount of the driving gas by the amount of movement of the bellows top; Based on the reference step in which the control software refers to the data table or approximate calculation formula of the movement amount, the reference data, and the change in the internal pressure of the breathing circuit caused by sending the driving gas before connecting to the patient airway, After calculating the system compliance including the leak amount and connecting to the patient airway, the leak amount is calculated. Previously plus the driving gas ventilation lost without system compliance; and a supply step of supplying to said bellows in the chamber.

  According to the present invention, it is possible to compensate for a ventilation loss during sub-volume control by sending in advance a part of the ventilation lost by system compliance including a leak.

In the above invention, in the calculation step, the pressure in the breathing circuit when the inside of the chamber is pressurized with the driving gas VB with the patient connection end closed before being connected to the patient airway is Ppl, and the pressure is released. When the pressure when the bellows is stable in contact with the ceiling of the chamber is PEEP, the functional cross-sectional area is SB, and the movement amount DB of the bellows top is the system compliance CS including the leak amount by In particular, this is called initial system compliance CSi.
CSi = VB / (Ppl-PEEP) = (SB × DB) / (Ppl-PEEP)
In the supplying step, the patient connection end is connected to the patient airway, the pressure in the breathing circuit when the inside of the chamber is pressurized with the driving gas VB is Ppl, the pressure is released, and the bellows is in contact with the ceiling of the chamber Assuming that the pressure when the pressure is stable is PEEP, an amount obtained by multiplying the CSi by the difference between Ppl and PEEP, that is, a driving gas amount obtained by adding CSi × (Ppl−PEEP) is supplied.

  Further, in the above invention, the time for maintaining the breathing circuit internal pressure Ppl when the inside of the chamber is pressurized with the driving gas VB is continued for a predetermined time, and after the expansion of the breathing circuit is completed, the predetermined time T (second) is further added. The method further includes the step of determining and displaying the leak amount VL = SB × ΔDB × 60 / T per minute of the breathing circuit from the change ΔDB of the movement amount DB of the bellows top during that time.

  According to the present invention, even when a bellows-in-chamber type ventilator is used, the loss of ventilation volume during metered amount control is compensated with sufficient accuracy while maintaining the advantage of the bellows-in-chamber type ventilator. An anesthesia system and a method for operating the anesthesia system can be provided.

It is a block diagram of the whole anesthesia system which shows embodiment of this invention centering on a piping system. It is a figure for demonstrating the operation | movement of inhalation in the bellows-in chamber, and expiration. It is a simplified diagram for explaining the principle of initial system compliance measurement. It is an acquisition method and data example of the data table or approximate calculation formula of the functional cross-sectional area SB and the movement amount DB of the bellows top. It is a figure explaining the measurement method of initial system compliance CSi and leak amount VL per minute concretely.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an entire anesthesia system showing an embodiment of the present invention centering on a piping system. As shown in FIG. 1, the anesthesia system 1 includes an anesthetic gas supply unit 2, a circulation type breathing circuit 3 including a bellows-in chamber 6, a surplus gas discharge circuit 4, and a driving gas generator 5.
The bellows-in chamber 6 is a main component of the ventilator (artificial respirator) along with the driving gas generator 5, but the breathing air passes through the inside of the bellows-in chamber 6, so that one part of the breathing circuit 3 is used. In this application, the following explanation will be made based on this concept.

The anesthetic gas supply unit 2 adds either nitrous oxide gas (N ₂ O) or air to oxygen (O ₂ ) or oxygen (O ₂ ), and vaporizes a volatile anesthetic in the vaporizer 26. The mixed gas is mixed and supplied to the breathing circuit 3 as fresh gas. The breathing circuit 3 is a circulation breathing circuit, and mixes fresh gas supplied from the anesthetic gas supply unit 2 and circulating air after absorbing and removing carbon dioxide from the exhaled air of the patient A, and sends them to the patient A as inspiration. The surplus gas discharge circuit 4 sucks the surplus gas from the surplus gas discharge valve 32 so as not to leak into the room via the surplus gas interface 33 and to prevent the harmful suction pressure from being exerted on the breathing circuit 3. To the source.

The anesthetic gas supply unit 2 includes oxygen (O ₂ ), nitrous oxide gas (N ₂ O), and air (AIR) pressure reducing valves 16, 18, 20, flow control valves 13, 14, 15, and a flow meter 21. 22 and 23, volatile anesthetic vaporizer 26, O ₂ flush valve 27 The vaporizer 26 introduces a mixed gas of oxygen (O ₂ ), nitrous oxide gas (N ₂ O), and air (AIR), and volatile anesthetics such as halothane, enflurane, isoflurane, sevoflurane, desflurane, etc. Vaporize and mix. The O ₂ flush valve 27 is provided so that oxygen can be supplied to the breathing circuit 3 without going through the pressure reducing valve, the flow rate adjusting valve / flow meter and the vaporizer 26.

The oxygen (O ₂ ) pressure reducing valve 16 uses oxygen gas (O ₂ ) from an existing O ₂ supply pipe or oxygen gas (O ₂ ) from an O ₂ cylinder via a cylinder pressure reducing valve 17. Supply piping corresponding to each case is connected. Also in the nitrous oxide gas (N ₂ O) pressure reducing valve 18, the existing N ₂ O If the supply pipe utilizing nitrous oxide gas (N ₂ O), or cylinder pressure reducing valve 19 N ₂ O gas cylinder via a The supply piping corresponding to each of the cases where nitrous oxide gas (N ₂ O) is used is connected. A supply pipe for introducing air from an existing AIR supply pipe is connected to the air (AIR) pressure reducing valve 20.

  The breathing circuit 3 includes an inhalation valve 10 that allows only inhalation to the patient, an exhalation valve 11 that allows only exhalation from the patient, a carbon dioxide absorption canister 12, a fresh gas on / off valve 28, a breathing circuit switching valve 29, an APL valve 30, and the like. It is a circulation type breathing circuit including. The inhalation / expiration passes through the bellows-in chamber 6 and is included in the breathing circuit 3.

  The carbon dioxide absorption canister 12 absorbs and removes carbon dioxide from the exhaled breath of the patient A, and circulates and uses the regenerated exhaled air that does not contain the carbon dioxide. The carbon dioxide absorption canister 12 is filled with a carbon dioxide absorbent such as soda lime. The fresh gas on-off valve 28 is an on-off valve that prevents the steady flow of fresh gas from being added to the amount of inspiration, and introduces fresh gas sent from the anesthetic gas supply unit 2 into the breathing bag during inspiration, and a breathing circuit during exhalation. 3 for introduction.

  An explanation of the operation of the bellows-in chamber is shown in FIG. Reference numeral 6 denotes a bellows-in chamber in which a bellows 6a that can be vertically expanded and contracted to supply internal gas to the breathing circuit 3 is arranged in a chamber 6b that is a transparent pressure vessel. The bellows 6a is usually made of a thin soft rubber or the like, and has a structure that can be expanded and contracted extremely sensitively by a pressure difference between the inside and the outside (inside the chamber).

The inside and outside of the bellows 6a (inside the chamber) are connected via a pop-off valve 6e having two gas inlets and outlets, and the gas inlet is received inside the pop-off valve 6e by receiving the pressure in the chamber. A diaphragm that opens and closes is provided.
In the intake phase, as shown in FIG. 2A, the surplus gas discharge valve 32 is closed, and the diaphragm of the pop-off valve 6e is allowed to flow inside and outside the bellows 6a by the pressure of the driving gas sent from the driving gas generator 5. The bellows 6 a is contracted by the driving gas that is shut off and flows into the chamber, and the inhaled gas is pushed out to the breathing circuit 3.
In the expiratory phase, the surplus gas discharge valve 32 is opened as shown in FIG. 5B, and when the surplus gas is discharged from the breathing circuit 3 and passes through the pop-off valve 6e, the diaphragm becomes a resistance and the bellows 6a. A constant differential pressure, for example, about 2 hPa is generated inside and outside. As a result, the bellows 6a swells and rises.

  The bellows-in chamber 6 is provided with a bellows position sensor 6d as measuring means. The bellows position sensor 6d measures the distance DB that the bellows top 6c moves downward from the ceiling of the chamber 6b that encloses the bellows top 6c, and sends the measured movement amount data to the control unit 7. The bellows position sensor 6d is constituted by, for example, a wire linear encoder, an ultrasonic or optical position sensor, a magnetostrictive displacement sensor, or the like.

  The breathing bag 33 is a compressible bag for manually sending inspiration to the patient A, and the anesthesia system 1 also serves as a reservoir for temporarily storing fresh gas during inhalation while using the ventilator. To do. The breathing bag 33 is prepared in various sizes according to the amount of inhaled air sent to the patient A, and can be exchanged as appropriate.

  The breathing circuit switching valve 29 switches the operation state of the anesthesia system 1 to automatic operation (ventilator operation) using the driving gas generator 5 that supplies gas for driving the bellows-in chamber 6 or manual operation using the breathing bag 33. . The APL valve 30 is provided in a flow path from the breathing circuit 3 to the surplus gas discharge circuit 4, and is used for pressure adjustment in the breathing circuit 3 during manual operation.

  The control unit 7 functions as a calculation unit and controls the operating state of the anesthesia system 1. The control unit 7 includes at least a signal input / output unit, a human interface, arithmetic processing means such as a microprocessor / CPU / MPU, and a memory as a storage unit. As a controller for the ventilator function and the monitor function, the control unit 7 processes signals from the human interface, the flow sensor 8, and the bellows position sensor 6d, and a surplus gas discharge valve 32, a fresh gas on-off valve 28, a breathing circuit switching valve 29, The driving gas generator 5 and the like are controlled. Moreover, if the control part 7 uses the device which has a signal input-output in the anesthetic gas supply part 2 and can be controlled, it can also take charge of flow measurement and flow volume adjustment.

  Between the breathing circuit 3 and the surplus gas discharge circuit 4, there is a surplus gas discharge valve 32. The surplus gas discharge valve 32 is closed at the time of inhalation during the automatic operation, that is, the use of the ventilator, and is opened at the time of exhalation. The opening and closing of the surplus gas discharge valve 32 is controlled by the control unit 7. Further, the gas discharged through the surplus gas discharge valve 32 is sucked by the suction source and then released as it is to the atmosphere, or decomposes and / or adsorbs an anesthetic, nitrous oxide gas or the like as necessary. From the atmosphere.

The inhalation valve 10 existing in the circulation type breathing circuit 3 operates so as to allow the flow of gas (inspiration) to the patient A but restrict the reverse flow. Similarly, the exhalation valve 11 operates so as to allow the flow of gas from the patient A (exhalation) but restrict the reverse flow. A part of the exhalation is carried to the carbon dioxide absorption canister 12 and the remaining part is discharged as surplus gas.
The driving gas generator 5 can select either a controlled amount control with the ventilation amount as a control target or a controlled pressure control with the ventilation pressure as a control target, and is controlled by the control unit 7.

FIG. 3 shows elements necessary for explaining the system compliance especially when the ventilator is used. FIG. 4 shows the driving amount VB, the moving amount DB, and the functional sectional area SB in the bellows-in chamber 6 in particular. A method for obtaining a data table or an approximate calculation formula describing the relationship will be described.
In the following, the principle explanations of [determination and storage of functional cross section SB], [measurement of system compliance CS and compensation of ventilation loss], and [measurement of leak amount per minute of breathing circuit] will be added.

[Determination and storage of functional cross section SB]
In FIG. 4, when the air amount VB is injected into the space between the bellows 6a and the chamber 6b with a syringe (drive gas generator 5) having a calibrated volume scale from the minimum amount to the maximum amount in the use range, The top 6c moves DB downward. A value obtained by dividing VB at this time by the movement amount DB of the bellows top 6c is defined as a functional cross-sectional area SB.
That is, the functional cross-sectional area SB is expressed by the following equation.
・ SB = VB / DB
The data table of the bellows top displacement DB and the functional cross-sectional area SB obtained by the above method, or an approximate calculation formula thereof, is stored in the memory in the control unit 7 and is referred to when necessary for control by the control software. Is done.
Further, when the bellows-in chamber 6 is actually operated by the driving gas generator 5, the VB injected by the syringe calls the corresponding SB from the memory based on the measured DB value, and drives the bellows. It is calculated and displayed as a quantity VB = SB × DB.

[Measurement of system compliance CS and compensation of ventilation loss]
In FIG. 3, the internal pressure of the breathing circuit 3 when the inside of the chamber 6b is pressurized with the driving gas VB is Ppl, and the pressure when the pressure is released and the bellows 6a is in contact with the ceiling of the chamber 6b and is stable is PEEP. When doing so, the control unit 7 obtains the system compliance CS including the leak amount by the following equation based on the data of the functional cross-sectional area SB.
CS = (VB-VI) / (Ppl-PEEP) = (SB × DB-VI) / (Ppl-PEEP)
As shown in FIG. 3, in the state where the patient connection end of the flow sensor 8 is closed before connecting to the patient airway, the intake air amount VI = 0, and in particular, the system compliance at this time is called initial system compliance and is expressed as CSi,
CSi = VB / (Ppl−PEEP) = (SB × DB) / (Ppl−PEEP)
The control unit 7 controls the drive gas generator 5 to send the drive gas, which is preliminarily added with a part of the ventilation amount CSi × (Ppl-PEEP) lost in the initial system compliance CSi, to the bellows-in chamber 6. It is possible to compensate for ventilation loss during metered volume control.

[Measurement of leak rate per minute of breathing circuit]
Further, the control unit 7 sufficiently extends the time for maintaining the Ppl, and continues to pressurize for a certain time T (seconds) after the expansion of the breathing circuit 3 is completed, and the amount of movement DB of the bellows top 6c during that time The amount of leakage VL = SB × ΔDB × 60 / T per minute of the breathing circuit 3 can be obtained from the amount of change ΔDB and displayed on a display (not shown).

Next, the operation will be described with reference to FIGS.
(1) First, as shown in FIG. 3, the patient connection end of the flow sensor 8 of the breathing circuit 3 is closed.
(2) Drive gas is sent from the drive gas generator 5 into the chamber 6b to pressurize the bellows 6a.
(3) As shown in FIG. 5, when pressurizing so that the internal pressure of the breathing circuit 3 becomes Ppl, the bellows top 6c moves downward by DB due to air compression and expansion of the circuit material. Moreover, the stable internal pressure PEEP of the breathing circuit 3 after releasing the pressurization is recorded.
At this time, the movement amount DB is measured by a bellows position sensor 6d attached to the bellows top 6c, and the control unit 7 calculates the functional cross-sectional area SB and the bellows driving amount from the data table or the approximate calculation formula as values corresponding to the DB. Get VB.

(4) Next, the control part 7 calculates | requires the initial stage system compliance of the respiration circuit 3 by CSi = VB / (Ppl-PEEP) from the result of said (1)-(3).
(5) When artificial respiration is performed with controlled volume control that sends a constant tidal volume, the loss of tidal volume due to system compliance is CSi x (Ppl-PEEP), so this loss is added to the driving gas in advance. Then, by driving the bellows-in chamber 6, a desired tidal volume can be obtained.

(6) In the case of (3), the time for maintaining the internal pressure Ppl of the breathing circuit 3 when the inside of the chamber 6b is pressurized with the drive gas VB is sufficiently extended, and further constant after the expansion of the breathing circuit 3 is completed. Pressurization is continued for a time T (seconds), and the amount of leak VL = SB × ΔDB × 60 / T per minute of the three respiratory cycles is obtained from the amount of change DB in DB during that time.

  Furthermore, an example of a method of measuring the initial system compliance CSi · leakage amount VL per minute will be described more specifically with reference to FIG. For example, the breathing operation is performed three times by sub-pressure control that maintains the inspiratory pressure Ppl of the breathing circuit at a constant value, for example, 30 hPa. The first time is a leveling operation, and immediately before that, as shown in FIG. 5A, it is confirmed that the bellows top 6c reaches the ceiling in the chamber 6b and is stable for the first time t1, Calibration DB = 0 is performed. In the first half of the next second and third inspiration phases, for example, during a period of t2 = 4 seconds, the air compression and the expansion of the circuit material are stabilized and the pressure of the entire breathing circuit 3 is equalized, as shown in FIG. Thus, the initial system compliance CSi of the breathing circuit 3 including the leak amount is measured. In the second half of the subsequent intake phase, for example, during a period of t3 = 6 seconds, as shown in FIG. 5C, if there is a leak, the bellows 6a is driven further downward to maintain 30 hPa. The amount of decrease for 6 seconds is converted into the amount VL for 1 minute. The results of the second and third times can be averaged to obtain the initial system compliance CSi and the leak amount VL per minute.

  According to the present embodiment, the mechanical advantage of the bellows-in-chamber type ventilator is achieved, and the distance control of the piston type ventilator is realized by adding a device for measuring the position of the bellows, thereby improving the disadvantages of both. can do.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications may be made within the scope of the gist of the present invention described in the claims. It can be changed. The operation method of the anesthesia system of the present invention is realized by the anesthesia system 1, and the measurement step, the storage step, the calculation step, and the supply step are controlled by the control unit 7 that executes a predetermined program.

DESCRIPTION OF SYMBOLS 1 Anesthesia system 2 Anesthesia gas supply part 3 Breathing circuit 4 Excess gas discharge circuit 5 Drive gas generator 6 Bellows in chamber 6a Bellows 6b Chamber 6c Bellows top 6d Bellows position sensor 6e Pop-off valve 7 Control part 8 Flow sensor 10 Intake valve 11 Exhalation Valve 12 Carbon dioxide absorption canister 26 Vaporizer 28 Fresh gas on-off valve

Claims (6)

In an anesthesia system including a circulatory breathing circuit having a fresh gas on / off valve that prevents a steady flow of fresh gas from being added to the inspiratory amount and a bellows-in chamber,
Measuring means for measuring the distance that the bellows top moves downward from the ceiling of the chamber that wraps the bellows;
When a predetermined amount of driving gas is injected into the space between the bellows and the chamber, the control software can refer to the movement amount of the bellows top and the functional cross-sectional area data obtained by dividing the predetermined amount by the movement amount. As a simple data table or approximate calculation formula, memory stored in advance before shipment from the factory,
Calculation to determine the system compliance including the leak amount based on the data table or approximate calculation formula of the movement amount and the functional cross-sectional area and the change in the internal pressure of the breathing circuit caused by sending the driving gas before connecting to the patient airway Means,
An anesthesia system comprising: a supply unit configured to supply a driving gas to which a ventilation amount lost in system compliance including the leakage amount is added in advance after being connected to a patient airway to the bellows-in chamber. The calculation means pressurizes the chamber with a driving gas with the patient connection end closed before connecting to the patient airway, and the amount of movement of the bellows top when the pressure in the breathing circuit is stabilized at a constant pressure Ppl. DB, the pressure when the pressure is released and the bellows is in contact with the ceiling of the chamber and the pressure is stable, PEEP, the value corresponding to the DB, the bellows driving amount referred from the data table or the approximate calculation formula When the functional cross-sectional area is VB and SB, the system compliance CS including the leak amount is obtained by the following formula, and this is particularly called the initial system compliance CSi,
CSi = VB / (Ppl-PEEP) = (SB × DB) / (Ppl-PEEP)
2. The anesthesia system according to claim 1, wherein the supply unit uses CSi × (Ppl-PEEP) as the driving gas to be added after being connected to a patient airway. The calculation means continues the time for maintaining the breathing circuit internal pressure Ppl when the inside of the chamber is pressurized with the driving gas VB for a predetermined time, and further adds the predetermined time T (seconds) after the expansion of the breathing circuit is completed. The pressure per minute, and the amount of change ΔDB of the movement amount DB of the bellows top during that time, the leak amount VL = SB × ΔDB × 60 / T per minute of the breathing circuit can be obtained and displayed. 2. The anesthesia system according to 2. In a method of operating an anesthesia system including a circulation breathing circuit having a fresh gas on-off valve that prevents a steady flow of fresh gas from being added to the intake amount and a bellows-in chamber,
A measuring step of measuring a distance by which the bellows top moves downward from a ceiling of a chamber enclosing the bellows by a measuring unit;
When a predetermined amount of driving gas is injected into the space between the bellows and the chamber, the control software can refer to the movement amount of the bellows top and the functional cross-sectional area data obtained by dividing the predetermined amount by the movement amount. As a simple data table or approximate calculation formula, a storage step for storing in advance before factory shipment;
Calculation to determine the system compliance including the leak amount based on the data table or approximate calculation formula of the movement amount and the functional cross-sectional area and the change in the internal pressure of the breathing circuit caused by sending the driving gas before connecting to the patient airway Steps,
And a supply step of supplying the bellows-in chamber with a driving gas on which a ventilation amount lost due to the system compliance is added in advance after connection to a patient airway. In the calculation step, the amount of movement of the bellows top when the inside of the chamber is pressurized with a driving gas with the patient connection end closed before being connected to the patient airway, and the pressure in the breathing circuit is stabilized at a constant pressure Ppl. DB, the pressure when the pressure is released and the bellows is in contact with the ceiling of the chamber and the pressure is stable, PEEP, the value corresponding to the DB, the bellows driving amount referred from the data table or the approximate calculation formula When the functional cross-sectional area is VB and SB, the system compliance CS including the leak amount is obtained by the following formula, and this is particularly called the initial system compliance CSi,
CSi = VB / (Ppl-PEEP) = (SB × DB) / (Ppl-PEEP)
5. The method of operating an anesthesia system according to claim 4, wherein in the supplying step, the added driving gas is CSi × (Ppl-PEEP). The time for maintaining the breathing circuit internal pressure Ppl when the inside of the chamber is pressurized with the driving gas VB is continued for a predetermined time, and after the expansion of the breathing circuit is completed, pressurization is continued for a predetermined time T (seconds). 6. The method according to claim 5, further comprising the step of obtaining and displaying a leak amount VL = SB × ΔDB × 60 / T per minute of the breathing circuit from a change amount ΔDB of the movement amount DB of the bellows top. To operate the anesthesia system.

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