Respiration loop flow sensor calibration gas circuit, system and calibration method

Abstract

The invention relates to the field of medical instruments, and discloses a breathing circuit flow sensor calibration gas circuit, system and calibration method.The breathing circuit flow sensor calibration gas circuit comprises a gas source module, and a flow monitoring module, a gas switching valve, a calibration branch, an inspiration branch, an expiration branch, a manual machine control development, a mechanical ventilation driving device and a waste gas purification system which are sequentially connected with the gas source module in series; the gas source module provides calibration gas, the flow monitoring module adjusts the calibration gas into standard flow gas, the standard flow gas is sequentially conveyed to the inspiration branch and the expiration branch to complete calibration of a breathing loop flow sensor, and the standard flow calibration gas is exhausted after being purified through the waste gas purification system. A flow sensor of an original flow monitoring module of an anaesthesia machine is used as a standard flow sensor, and an original flow adjusting device and an original gas on-off device of the flow monitoring module are used for adjusting calibration gas for guaranteeing flow, so that the flow sensor of a breathing loop is calibrated; a standard flow sensor does not need to be additionally arranged or an external standard flow sensor does not need to be connected.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more particularly to a calibration air path and automatic calibration system for a breathing circuit flow sensor, and also to a calibration method applied to the automatic calibration system for the breathing circuit flow sensor. Background Technology

[0002] The respiratory circuit flow sensor in an anesthesia machine is primarily used to measure the inspiratory and expiratory flow rates of the patient during anesthesia. Data from the inspiratory flow sensor provides feedback to control the expiratory valve, allowing for mechanical ventilation at preset flow rates, pressures, and tidal volumes. Data from the expiratory flow sensor calculates the patient's expiratory flow rate, tidal volume, and other respiratory mechanics parameters. Therefore, the accuracy of the respiratory circuit flow sensor significantly impacts the precision of the anesthesia machine's tidal volume control and the sensitivity of the patient's spontaneous inspiratory trigger. Large deviations in the respiratory circuit flow sensor can lead to inaccurate tidal volume readings and inaccurate spontaneous inspiratory trigger thresholds.

[0003] In existing technologies, respiratory circuit flow sensors typically use a throttling device to generate a pressure differential. A differential pressure sensor detects this pressure differential and generates an analog or digital signal. The anesthesia machine's control system receives this signal, converts it into a pressure differential value, and then uses a pressure-flow rate conversion table to calculate the flow rate. During prolonged use or cleaning and maintenance of the respiratory circuit flow sensor, the flow rate-pressure relationship can change, causing significant or inaccurate deviations in the flow rate calculated by the anesthesia machine's control system based on the pressure differential generated by the throttling device. If the flow sensor is not calibrated, the detected flow rate deviation will exceed the tolerance range, leading to inaccurate ventilation flow control by the anesthesia machine. After calibration (i.e., updating the pressure-flow rate conversion table of the anesthesia machine's control system based on the flow rate value of the diaphragm and the pressure differential across the diaphragm), the diaphragm can continue to be used, extending its service life. Therefore, regular calibration of the respiratory circuit flow sensor is necessary.

[0004] Existing anesthesia machines are generally calibrated manually by setting a standard flow sensor in the drive air circuit. The flow sensor is calibrated by removing the pleated bag inside the ventilation drive bellows and connecting it in series with the flow sensor in the breathing circuit. This operation is complicated and cumbersome, requires disassembling multiple parts, increases the wear and tear on the parts, raises the risk of leakage, and cannot achieve automated calibration. Summary of the Invention

[0005] To address the problems of repeated disassembly, complex operation, and increased risk in calibrating breathing circuit flow sensors in existing technologies, this invention provides a calibration air path and calibration method for breathing circuit flow sensors. This method enables automatic calibration of flow sensors, simplifies operation steps, avoids the risks of air leakage and errors caused by manual operation, and improves calibration accuracy.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a breathing circuit flow sensor calibration air path, comprising an air source module, a flow monitoring module and a breathing circuit connected in series with the air source module, wherein the breathing circuit includes an inspiratory branch and an expiratory branch; The gas source module provides calibration gas to the calibration gas path and delivers the calibration gas to the flow monitoring module; The flow monitoring module includes a switching valve, a proportional valve, and a standard flow sensor. The outlet of the standard flow sensor is connected to the intake branch. The switching valve is used to control the on / off of the calibration gas. The proportional valve and the standard flow sensor are used to adjust the flow rate of the calibration gas and deliver the calibration gas at the standard flow rate to the intake branch. The inhalation branch includes an inhalation flow sensor, the exhalation branch includes an exhalation flow sensor, and the inhalation branch and the exhalation branch are connected by a connecting tube. The calibration gas output by the flow monitoring module passes sequentially through the inspiratory flow sensor and the expiratory flow sensor before being discharged from the outlet of the expiratory branch.

[0007] The standard flow sensor can be an electronic flow sensor, a mechanical flow sensor, or other calibration-free flow sensors.

[0008] Furthermore, it also includes an inhalation one-way valve, an exhalation one-way valve, and a carbon dioxide absorption branch. The inhalation one-way valve is located at the front end of the inhalation branch, and the exhalation one-way valve is located at the rear end of the exhalation branch. One end of the carbon dioxide absorption device is connected to the rear end of the exhalation one-way valve, and the other end is connected to the front end of the inhalation one-way valve.

[0009] A calibration system gas discharge scheme, wherein the expiratory branch includes a water collection cup, which is detachably installed between the expiratory flow sensor and the expiratory one-way valve. The calibration gas passes sequentially through a standard flow sensor, an inspiratory flow sensor, and an expiratory flow sensor, and is discharged from the installation port after the water collection cup is detached.

[0010] Another calibration system gas exhaust scheme, the breathing circuit also includes a mechanical ventilation drive device, a manual drive device and an exhaust gas purification system; The air inlet of the mechanical ventilation drive device is connected to the air outlet of the exhalation branch, and the air outlet is connected to the exhaust gas purification system through the exhalation valve. The manual drive device includes a manual mechanical control switch valve, a manual bladder, and an APL valve. The manual mechanical control switch valve is installed on the connecting pipeline between the mechanical ventilation drive device and the exhalation path. One end of the manual bladder is connected to the exhalation branch via the manual mechanical control switch valve, and the other end is connected to the exhaust gas purification system via the APL valve. The manual mechanical control switch valve controls the switching of the gas output from the exhalation branch between the mechanical ventilation drive device and the manual bladder valve.

[0011] The specific flow direction of the calibration gas is as follows: when calibrating the inspiratory flow sensor and the expiratory flow sensor, the calibration gas passes sequentially through the standard flow sensor, the inspiratory flow sensor, the expiratory flow sensor, the manual mechanical control switch valve, the mechanical ventilation drive device, and the expiratory valve before being discharged to the exhaust gas purification system. Alternatively, the calibration gas may be sequentially passed through a standard flow sensor, an inspiratory flow sensor, an expiratory flow sensor, a manual mechanical control switch valve, a manual bladder, and an APL valve before being discharged to the exhaust gas purification system.

[0012] A calibration gas delivery system, including a calibration branch and a gas switching valve; The outlet of the flow monitoring module is connected to the inlet of the gas switching valve. The inlet of the calibration branch is connected to the outlet of the gas switching valve, and the outlet of the calibration branch is connected between the carbon dioxide absorption branch and the intake flow sensor.

[0013] Furthermore, the outlet of the calibration branch is connected between the inlet check valve and the inspiratory flow sensor. The calibration gas output by the gas source module is adjusted to a standard flow rate by the flow monitoring module and then discharged sequentially through the gas switching valve, the calibration branch, the inspiratory flow sensor, and the expiratory flow sensor.

[0014] Furthermore, an airflow switch component is provided on the carbon dioxide absorption branch. When calibrating the inspiratory flow sensor and the expiratory flow sensor, the airflow switch component prevents airflow from passing through the carbon dioxide absorption branch. The outlet of the calibration branch is connected between the carbon dioxide absorption branch and the inlet check valve. The calibration gas output by the gas source module is adjusted to the standard flow rate by the flow monitoring module, and then passes through the gas switching valve, calibration branch, inhalation check valve, inhalation flow sensor, and expiration flow sensor in sequence before being discharged.

[0015] Furthermore, the carbon dioxide absorption branch includes a carbon dioxide absorption device and a bypass valve. The bypass valve is installed in the bypass branch. One end of the bypass branch is connected to the exhalation branch, and the other end is connected to the inhalation branch. The airflow switch component is a switch valve installed in the carbon dioxide absorption branch or a one-way valve installed in the bypass branch.

[0016] Another calibration gas delivery scheme also includes an anesthetic gas delivery branch, which includes an anesthetic gas delivery device and an anesthetic branch check valve. The outlet of the flow monitoring module is connected to the inlet of the anesthetic gas delivery device. The outlet of the anesthetic gas delivery device is connected to the inspiratory flow sensor after passing through the anesthetic branch check valve and the inspiratory check valve in sequence. The carbon dioxide absorption branch is connected between the anesthetic branch check valve and the inspiratory check valve.

[0017] Specifically, an airflow switch component is provided on the carbon dioxide absorption branch. When calibrating the inspiratory flow sensor and the expiratory flow sensor, the airflow switch component prevents airflow from passing through the carbon dioxide absorption branch. The calibration gas passes sequentially through the standard flow sensor, the anesthesia branch, the anesthesia branch check valve, the inspiratory check valve, the inspiratory flow sensor, the expiratory flow sensor, the expiratory check valve, and the manual mechanical control switch valve, and is then discharged to the waste gas purification system through the mechanical ventilation drive device or the manual ventilation device.

[0018] Furthermore, the gas source module includes at least one of an oxygen branch and an air branch, the calibration gas is either oxygen or air, and the air inlet of the gas source module can be connected to an external gas or an internal gas.

[0019] Specifically, the calibration gas can be oxygen or air, and the oxygen branch and air branch correspond to the corresponding on / off valve, proportional valve and standard flow sensor in the flow monitoring module, respectively.

[0020] An automatic calibration system includes a control system, a data acquisition module, a data processing module, and a calibration gas path. The control system is connected to the calibration gas path and is used to control the output calibration gas flow rate of the calibration gas path. The data acquisition module is connected to an inspiratory flow sensor and an expiratory flow sensor in the calibration gas path, respectively, and is used to acquire the ADC values ​​output by the inspiratory flow sensor and the expiratory flow sensor. The data processing module is connected to the control system and the data acquisition module, respectively, and is used to process the data output by the control system and the data acquisition module.

[0021] A calibration method, applied to the aforementioned automatic calibration system, includes the following steps: S1 builds a calibration system by connecting a standard flow sensor, an inspiratory flow sensor, and an expiratory flow sensor in series on a single airway. The S2 control system controls the standard flow sensor to output calibration gas at a standard flow rate, and acquires the ADC values ​​output by the inspiratory flow sensor and expiratory flow sensor respectively through the data acquisition module. S3 presets the flow rate gradient and adjusts the output flow rate of the standard flow sensor in sequence. It then collects the ADC values ​​output by the corresponding inspiratory flow sensor and expiratory flow sensor by sending multiple standard flow rate nodes. S4 summarizes the multiple standard flow rates set and the corresponding ADC values ​​collected by the data acquisition module to construct a "flow rate-ADC value" data table for the inspiratory flow sensor and the expiratory flow sensor. S5 uses a data fitting algorithm to fit the "flow rate-ADC value" to construct a flow rate calculation model and complete the calibration of the inspiratory flow sensor and expiratory flow sensor.

[0022] This calibration method is based on the correspondence between a standard flow rate reference and the electrical signals of the flow sensor to be calibrated (both the inspiratory and expiratory flow sensors in this invention are flow sensors to be calibrated). The standard flow sensor provides a precise and controllable constant standard flow rate. The analog-to-digital converter (ADC) output values ​​of the flow sensor to be calibrated are collected at different standard flow rates to construct a "flow rate-ADC value" data table. Then, a mathematical model is obtained through data fitting. Finally, the actual flow rate is calculated by inverting the ADC measurement value. The process of constructing the flow rate calculation model of the flow sensor to be calibrated is the calibration process. Once the flow rate calculation model of the flow sensor to be calibrated is completed, the calibration of the flow sensor to be calibrated is completed.

[0023] Specifically, in step S1, the step of setting up the calibration system includes connecting the standard flow sensor and the inspiratory branch, connecting the inspiratory branch and the expiratory branch, and connecting the expiratory branch output end to the outside. The calibration gas can be discharged to the outside of the anesthesia system after passing through the standard flow sensor, the expiratory branch and the inspiratory branch in sequence.

[0024] During the setup of the calibration system, it is necessary to ensure that the calibration gas path is well sealed and there is no gas leakage, and to ensure that the standard flow sensor, inspiratory flow sensor and expiratory flow sensor are in the same fluid environment to avoid environmental factors from interfering with the calibration accuracy.

[0025] Specifically, in step S2, the standard flow rate is defined as the flow rate value displayed by the standard flow sensor fluctuating within a preset error range.

[0026] Specifically, the error value is set to ±0.1%F·S.

[0027] In this invention, the calibration gas flow rate of the first set of constant standard flow rate output by the standard flow sensor is denoted as F1, and the corresponding ADC value is denoted as ADC1. The data of the two are recorded and the correspondence between the standard flow rate F1 and ADC1 is established.

[0028] Specifically, in step S3, multiple standard flow rate nodes cover the measurement range of the inspiratory flow sensor and the expiratory flow sensor.

[0029] Specifically, the output flow rate of the standard flow sensor is adjusted once, and denoted as F2, F3, F4...Fn, where n≥3; for each set standard flow rate Fᵢ (i=2,3,…,n), the corresponding ADC output value ADCᵢ is recorded, and this process is repeated sequentially with F2 and ADC2, F3 and ADC3, ..., Fn. n With ADC n The corresponding data collection.

[0030] Specifically, in step S5, during the fitting process, it is also necessary to select a polynomial of appropriate order based on the distribution characteristics of the data. The polynomial includes first-order, second-order, or higher-order polynomials.

[0031] By constructing a flow rate calculation model and calibrating the inspiratory and expiratory flow rate sensors, in subsequent actual measurements, it is only necessary to collect the current ADC measurement values ​​output by the inspiratory and / or expiratory flow rate sensors and substitute them into the polynomial calculation model to quickly and accurately calculate the current actual flow rate.

[0032] The beneficial effects of this invention are: 1. By using the flow sensor of the original flow monitoring module of the anesthesia machine as the standard flow sensor, the inspiratory flow sensor and expiratory flow sensor in the breathing circuit can be calibrated using the original flow adjustment device and gas on / off device of the flow monitoring module. There is no need to add an additional standard flow sensor or connect an external standard flow sensor to complete the calibration of the flow sensor in the breathing circuit. 2. By setting up a calibration branch to directly connect the flow monitoring module with the inspiratory branch, the calibration gas can flow directly to the inspiratory branch through the calibration branch during the calibration process, without flowing through the anesthetic vaporizer, thus avoiding the risk of anesthetic drugs being carried out during calibration. 3. By outputting the calibration gas to the exhaust gas absorption system, the risk of the calibration gas carrying anesthetic gas and being directly discharged outside the anesthesia machine, thus avoiding harm to the user, can be avoided.

[0033] 4. An airflow switch is installed in the carbon dioxide absorption branch to prevent calibration gas from being directly discharged through the carbon dioxide absorption branch during calibration, which could lead to gas leakage. The standard flow sensor, inspiratory flow sensor, and expiratory flow sensor are in different fluid environments, which could cause calibration failure. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation of the present invention. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0035] Figure 1 Diagram of the calibration gas path structure for flow sensors in existing technology; Figure 2 for Figure 1 Schematic diagram of gas flow direction during medium flow sensor calibration; Figure 3 This is a structural block diagram of one embodiment of the present invention; Figure 4 for Figure 3 Schematic diagram of medium flow sensor calibration; Figure 5 This is a pneumatic circuit block diagram according to an embodiment of the present invention; Figure 6 for Figure 5 A diagram of the gas path structure in one of the diagrams; Figure 7 for Figure 6 Schematic diagram of gas flow direction during calibration; Figure 8 for Figure 6 Schematic diagram of gas flow direction during calibration; Figure 9 for Figure 5 A diagram of the gas path structure in one of the diagrams; Figure 10 for Figure 9 Schematic diagram of gas flow direction during calibration; Figure 11 for Figure 5 A diagram of the gas path structure in one of the diagrams; Figure 12 for Figure 11 Schematic diagram of gas flow direction during calibration; Figure 13 for Figure 11 Schematic diagram of gas flow direction during calibration; Figure 14 for Figure 5 A diagram of the gas path structure in one of the diagrams; Figure 15 for Figure 14 Schematic diagram of gas flow direction during calibration; Figure 16 This is a gas path structure diagram of one embodiment of the present invention; Figure 17 for Figure 16Schematic diagram of gas flow direction during calibration; Figure 18 for Figure 16 Schematic diagram of gas flow direction during calibration; Figure 19 This is a gas path structure diagram of the carbon dioxide absorption branch in this invention; Figure 20 This is a block diagram of the automatic calibration system of the present invention; Figure 21 This is a flowchart of the flow calibration method of the present invention.

[0036] The system includes: 1. Gas source module; 2. Flow monitoring module; 3. Anesthetic gas delivery device; 41. Inhalation branch; 42. Exhalation branch; 421. Water collection cup; 43. Carbon dioxide absorption branch; 431. Carbon dioxide absorption tank; 432. Bypass system; 44. Connecting pipeline; 5. Mechanical ventilation drive device; 6. Exhalation valve; 7. Waste gas purification system; 8. Manual airbag; 9. Calibration branch; T1. First switching valve; T2. Second switching valve; T3. Third switching valve. T4, First Flow Valve; T5, Second Flow Valve; T6, Manual Control Switch; T7, Gas Path Switching Valve; T8, Fourth Switch Valve; F1, First Standard Flow Sensor; F2, Second Standard Flow Sensor; F3, Inspiratory Flow Sensor; F4, Exhalation Flow Sensor; C1, First Check Valve; C2, Second Check Valve; C3, Third Check Valve; C4, Fourth Check Valve; C5, Fifth Check Valve; C6, Sixth Check Valve; C7, Seventh Check Valve. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Existing anesthesia machines typically undergo manual calibration by installing a standard flow sensor in the drive airway. This is done by removing the pleated bag inside the ventilation drive bellows and connecting it in series with the flow sensor in the breathing circuit, thus calibrating the flow sensor. Figure 1 and Figure 2As shown, the specific calibration steps are as follows: First, remove the bellows and take out the internal folded bladder, connecting the standard flow sensor in series with the breathing circuit flow sensor; then reinstall the bellows, ensuring a single-path connection between the drive circuit and the breathing circuit; next, turn the manual control switch to the machine control state, seal the patient outlet of the breathing circuit, and remove the water collection cup; finally, adjust the proportional valve of the drive gas path through the control system to adjust the drive gas to the required calibration flow value. The adjusted drive gas passes through the calibration flow sensor, carbon dioxide absorption branch, inspiratory flow sensor, and expiratory flow sensor, and is discharged to the outside through the outlet after the water collection cup is removed; during this process, the flow rate of the standard flow sensor is connected to the flow rates of the inspiratory and expiratory flow sensors, and the flow rates of the inspiratory and expiratory flow sensors are calibrated through the standard flow sensor in the drive gas path; after calibration, reinstall the water collection cup and folded bladder. This operation is complex and cumbersome, requiring repeated disassembly and reassembly of multiple components such as the bellows, folded bladder, and water collection cup, increasing the risk of leakage, shortening the lifespan of components, and failing to achieve automated calibration.

[0039] This invention uses the flow sensor of the original flow monitoring module of the anesthesia machine as the standard flow sensor. It utilizes the original flow adjustment device and gas on / off device of the flow monitoring module to calibrate the inspiratory flow sensor and expiratory flow sensor in the breathing circuit. The calibration of the breathing circuit flow sensor can be completed without adding an additional standard flow sensor or connecting an external standard flow sensor. The following is a detailed description with reference to the accompanying drawings.

[0040] like Figure 3 and Figure 4 As shown, an embodiment of a breathing circuit flow sensor calibration airway includes a gas source module 1, a flow monitoring module 2, an inspiratory branch 41 and an expiratory branch 42. The inspiratory branch 41 and the expiratory branch 42 are connected by a connecting pipe 44 to form a breathing circuit. The flow monitoring module 2 includes a standard flow sensor F, an inspiratory flow sensor F3 is installed in the inspiratory branch 41, and an expiratory flow sensor F4 is installed in the expiratory branch 42. Gas source module 1 provides calibration gas to the calibration gas path and delivers the calibration gas to flow monitoring module 2; The flow monitoring module 2 adjusts the calibration gas flow rate and outputs calibration gas at the standard flow rate, which is then discharged after passing through the inspiratory flow sensor F3 and the expiratory flow sensor F4 in sequence.

[0041] A standard flow sensor, an inspiratory flow sensor, and an expiratory flow sensor are connected in series in a gas path. Based on the principle that the flow rate is equal under the same fluid environment, the gas flow rate at the inspiratory flow sensor and the expiratory flow sensor is equal to the gas flow rate output by the standard flow sensor, so as to calibrate the inspiratory flow sensor and the expiratory flow sensor.

[0042] like Figure 5 and Figure 6 As shown, the gas source module 1 includes at least one of the oxygen branch and the air branch, that is, the calibration gas is one of oxygen or air. The air inlet of the gas source module 1 can be connected to an external gas, such as a gas cylinder or a central gas supply system, or it can use the gas generated internally by the anesthetic, such as an oxygen generator or an air compressor.

[0043] This embodiment uses three common gas source modules for anesthesia machines—oxygen branch, air branch, and nitrous oxide branch—as examples for illustration. The output calibration gas can be oxygen, air, or a mixture of air and nitrous oxide. Under normal circumstances, oxygen or air is used as the calibration gas for calibration. The gas source module 1 includes an oxygen branch, an air branch, and a nitrous oxide branch, which respectively input oxygen, air, and nitrous oxide into the flow monitoring module 2; the flow monitoring module includes a first switching valve T1, a second switching valve T2, a third switching valve T3, a first flow valve T4, a second flow valve T5, a first standard flow sensor F1, and a second standard flow sensor F2. The outlet ends of the first standard flow sensor F1 and the second standard flow sensor F2 are connected and connected to the inhalation branch 41; The first switching valve T1 of the flow monitoring module 2 corresponds to the oxygen branch of the gas source module. The oxygen output from the oxygen branch flows out of the flow monitoring module 2 after passing through the first switching valve T1, the first flow valve T4, and the first standard flow sensor F1. The second switching valve T2 of the flow monitoring module 2 corresponds to the air branch of the gas source module, and the third switching valve T3 corresponds to the nitrous oxide branch. The air output from the air branch passes through the second switching valve T2 and mixes with the nitrous oxide passing through the third switching valve T3. Then it flows out of the flow monitoring module 2 after passing through the second flow valve T5 and the second standard flow sensor F2. Among them, the first switching valve T1 is used to control the on and off of the input oxygen, the first flow valve T4 and the first standard flow sensor F1 are used to adjust the flow rate of the calibration gas to the standard flow gas, and deliver the standard flow gas to the intake branch 41. In some embodiments, the flow monitoring module 2 further includes a first one-way valve C1, a second one-way valve C2, and a third one-way valve C3, wherein the first one-way valve C1 is disposed between the first switching valve T1 and the first flow valve T4 to prevent gas from flowing back into the oxygen branch; the second one-way valve C2 is disposed between the second switching valve T2 and the second flow valve T5 to prevent gas from flowing back into the air branch; and the third one-way valve C3 is disposed between the third switching valve T3 and the second flow valve T5 to prevent gas from flowing back into the nitrous oxide branch.

[0044] The inhalation branch 41 includes an inhalation flow sensor F3 and a fifth one-way valve C5, with the inhalation one-way valve C5 located at the front end of the inhalation flow sensor F3; the exhalation branch 42 includes an exhalation flow sensor F4 and a sixth one-way valve C6, with the sixth one-way valve C6 located at the rear end of the exhalation flow sensor F4; the outlet end of the inhalation branch 41 is connected to the exhalation branch 42 via a connecting pipe 44, and the outlet end of the exhalation branch 42 is connected to the inhalation branch 41 via a carbon dioxide absorption branch 43, with one end of the carbon dioxide absorption branch 43 connected to the rear end of the sixth one-way valve C6 and the other end connected to the front end of the fifth one-way valve C5.

[0045] In this embodiment, the fifth one-way valve C5 is an inhalation one-way valve, and the sixth one-way valve C6 is an exhalation one-way valve.

[0046] In one embodiment, the outlet of the flow monitoring module 2 is connected to the inlet of the gas switching valve T7. One outlet of the gas switching valve T7 is connected to the inhalation branch 41 through the anesthetic gas delivery device 3 and the fourth one-way valve C4, wherein the anesthetic gas delivery device 3 and the fourth one-way valve C4 are the anesthetic gas delivery branches; the other outlet of the gas switching valve T7 is connected to the inhalation branch 41 through the calibration branch 9.

[0047] This embodiment also includes a mechanical ventilation drive device 5, a manual drive device, and an exhaust gas purification system 7; The air inlet of the mechanical ventilation drive device 5 is connected to the air outlet of the exhalation branch 42, and the air outlet of the mechanical ventilation drive device 5 is connected to the exhaust gas purification system 7 through the exhalation valve 6. The manual drive device includes a manual control switch T6 and a manual bladder 8. The manual control switch T6 is installed on the connecting pipeline between the mechanical ventilation drive device 5 and the exhalation path 42. One end of the manual bladder 8 is connected to the exhalation branch 42 through the manual control switch T6, and the other end is connected to the exhaust gas purification system 7 through the APL valve. The manual control switch T6 controls the gas output from the exhalation branch 42 to switch between the mechanical ventilation drive device 5 and the manual bladder 8.

[0048] In this embodiment, the outlet of calibration branch 9 is connected between the fifth one-way valve C5 and the intake flow sensor F3. Because the fifth one-way valve C5 can only allow gas to flow towards the intake flow sensor F3, the gas flowing out from the outlet of calibration branch 9 can only flow towards the intake flow sensor F3.

[0049] In this embodiment, the standard flow sensor F can be an electronic flow sensor, a mechanical flow sensor, or other calibration-free flow sensors.

[0050] The following explanation uses oxygen as the calibration gas to illustrate the specific flow direction of the calibration gas.

[0051] like Figure 7As shown, in one embodiment of the present invention, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the gas path switching valve T7 is connected to the calibration branch 9, the manual mechanical control switch T6 is closed to put the device into mechanical control ventilation, and the patient end air outlet on the connecting pipe 44 is sealed.

[0052] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the inhalation flow sensor F3, the connecting pipe 44, the exhalation flow sensor F4, the sixth one-way valve C6, the manual control switch T6, the mechanical ventilation drive device 5, and the exhalation valve 6 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0053] like Figure 8 As shown, in one optional embodiment of the present invention, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the gas path switching valve T7 is connected to the calibration branch 9, the manual control switch T6 is opened to put the device into manual control ventilation, and the patient end outlet on the connecting pipe 44 is sealed.

[0054] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the inhalation flow sensor F3, the connecting pipe 44, the exhalation flow sensor F4, the sixth one-way valve C6, the manual mechanical control switch T6, and the manual bladder 8 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0055] The calibration gas is purified by the exhaust gas purification system before being discharged, which can avoid releasing the original mixture of anesthetic gas in the breathing airway into the room and reduce the risk of anesthetic gas harming medical staff.

[0056] like Figure 9 and Figure 10 As shown, in a feasible embodiment of the calibration airway, a removable water collection cup 421 is provided between the expiratory flow sensor F4 and the sixth one-way valve T6. When calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the airway switching valve T7 is connected to the calibration branch 9, the patient end outlet on the connecting pipe 44 is sealed, and the water collection cup is removed.

[0057] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the inhalation flow sensor F3, the connecting pipe 44, and the exhalation flow sensor F4, and is then discharged from the installation port after the water collection cup 321 has been removed.

[0058] like Figure 11 As shown, the outlet of calibration branch 9 is connected between the fourth one-way valve C4 and the fifth one-way valve C5, and an airflow switch component is provided on carbon dioxide absorption branch 43.

[0059] In one feasible embodiment, the carbon dioxide absorption branch 43 includes a carbon dioxide absorption tank 431 and a bypass system 432. The bypass system includes a bypass valve and a bypass branch. The bypass valve is disposed in the bypass branch. One end of the bypass branch is connected to the exhalation branch and the inhalation branch. The airflow switch component is a seventh one-way valve C7 disposed on the bypass branch.

[0060] The bypass system 432 ensures that the breathing circuit remains unobstructed when the carbon dioxide absorption canister 431 is removed and the carbon dioxide absorbent is replaced, enabling normal ventilation for the patient.

[0061] like Figure 19 As shown, the airflow switch component can also be a fourth switch valve T8 disposed on the carbon dioxide absorption branch 43. In one embodiment, the fourth switch valve T8 is disposed between the carbon dioxide absorption canister 431 and the inhalation branch 41. In other embodiments, the fourth switch valve T8 is disposed between the carbon dioxide absorption canister 431 and the exhalation branch 42.

[0062] An airflow switch component is installed on the carbon dioxide absorption branch 43 to prevent the calibration airflow from flowing back from the carbon dioxide absorption branch 43 during calibration, ensuring that the calibration gas can only flow to the inhalation flow sensor F3.

[0063] In this embodiment, the airflow switch component is the seventh one-way valve C7 located on the bypass branch, which is used as an example.

[0064] like Figure 12 As shown in the embodiment of a calibration gas flow direction, in an optional embodiment of the present invention, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the gas path switching valve T7 is connected to the calibration branch 9, the manual control switch T6 is opened to put the device into manual control ventilation, the patient end outlet on the connecting pipe 44 is sealed, and at the same time the carbon dioxide absorption canister 431 disassembly switch is opened to disconnect the carbon dioxide absorption canister 431 from the breathing circuit, and the breathing circuit is connected to the bypass system 432.

[0065] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the fifth one-way valve C5, the inhalation flow sensor F3, the connecting pipe 44, the exhalation flow sensor F4, the sixth one-way valve C6, the manual control switch T6, and the manual bladder 8 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0066] like Figure 13 As shown, in a calibration gas flow embodiment, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the gas path switching valve T7 is connected to the calibration branch 9, the manual control switch T6 is closed to put the device into mechanical control ventilation, the patient end outlet on the connecting pipe 44 is sealed, and the carbon dioxide absorption canister 431 disassembly switch is opened to disconnect the carbon dioxide absorption canister 431 from the breathing circuit, and the breathing circuit is connected to the bypass system 432.

[0067] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the fifth one-way valve C5, the inhalation flow sensor F3, the connecting pipe 44, the exhalation flow sensor F4, the sixth one-way valve C6, the manual control switch T6, the mechanical ventilation drive device 5, and the exhalation valve 6 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0068] like Figure 14 and Figure 15 As shown, the outlet of calibration branch 9 is connected between the fourth one-way valve C4 and the fifth one-way valve C5. A detachable water collection cup 421 is provided between the expiratory flow sensor F4 and the sixth one-way valve T6. At the same time, an airflow switch component is provided on the carbon dioxide absorption branch 43. In this embodiment, the airflow switch component is the seventh one-way valve C7 provided on the bypass branch as an example.

[0069] like Figure 15 As shown, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the air path switching valve T7 is connected to the calibration branch 9, the patient end outlet on the connecting pipe 44 is sealed, the water cup is removed, and at the same time the carbon dioxide absorption canister 431 disassembly switch is opened to disconnect the carbon dioxide absorption canister 431 from the breathing circuit, and the breathing circuit is connected to the bypass system 432.

[0070] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the fifth one-way valve C5, the inhalation flow sensor F3, the connecting pipe 44, and the exhalation flow sensor F4, and is then discharged from the installation port after the water collection cup 321 has been disassembled.

[0071] It is known that when the airflow switch component is the fourth switch valve T8 installed on the carbon dioxide absorption branch 43, it is not necessary to open the carbon dioxide absorption tank 431 to remove the switch when calibrating the flow sensor. The same purpose can be achieved simply by closing the fourth switch valve T8 so that the calibration gas cannot flow through the carbon dioxide absorption branch 43.

[0072] like Figure 16 As shown, in a feasible embodiment, the outlet of the flow monitoring module 2 is directly connected to the anesthetic gas delivery device 3, the fourth one-way valve C4 is connected to the inhalation branch 41, and an airflow switch component is provided on the carbon dioxide absorption branch 43. This airflow switch component can be the seventh one-way valve C7 provided on the bypass branch, or the fourth switch valve T8 provided on the carbon dioxide absorption branch 43.

[0073] like Figure 17 As shown, taking the seventh one-way valve C7, which is set on the bypass branch, as an example, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the manual control switch T6 is opened to put the device into manual control ventilation, the patient end outlet on the connecting pipe 44 is sealed, and the carbon dioxide absorption canister 431 disassembly switch is opened to disconnect the carbon dioxide absorption canister 431 from the breathing circuit. The breathing circuit is connected to the bypass system 432, and the anesthetic gas delivery device 3 is closed to make the anesthetic gas evaporation rate 0.

[0074] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the anesthetic gas delivery device 3, the fourth one-way valve C4, the fifth one-way valve C5, the inspiratory flow sensor F3, the connecting pipe 44, the expiratory flow sensor F4, the sixth one-way valve C6, the manual control switch T6, and the manual bladder 8 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0075] In this embodiment, there is no need to add a calibration branch 9. The original gas path system of the anesthesia machine can be used. Only an airflow switch component needs to be set in the carbon dioxide absorption branch 43. During calibration, the gas is prevented from flowing through the carbon dioxide absorption branch 43 to achieve the calibration purpose. At the same time, the calibration gas is discharged after being purified by the exhaust gas purification system, which can avoid the risk of anesthetic drugs being carried in the calibration gas due to leakage of the anesthetic gas delivery device.

[0076] like Figure 18 As shown, in a calibration gas flow embodiment, when calibrating the inspiratory flow sensor F3 and the expiratory flow sensor F4, the second switch valve T2 and the third switch valve T3 are closed, the first switch valve T1 is opened, the gas path switching valve T7 is connected to the calibration branch 9, the manual control switch T6 is closed to put the device into mechanical control ventilation, the patient end outlet on the connecting pipe 44 is sealed, the carbon dioxide absorption canister 431 disassembly switch is opened to disconnect the carbon dioxide absorption canister 431 from the breathing circuit, the breathing circuit is connected to the bypass system 432, and the anesthetic gas delivery device 3 is closed to make the anesthetic gas evaporation rate 0.

[0077] The calibration gas (oxygen in this embodiment) passes sequentially through the first switching valve T1, the first one-way valve C1, the first flow valve T4, the first standard flow sensor F1, the gas path switching valve T7, the calibration branch 9, the fifth one-way valve C5, the inhalation flow sensor F3, the connecting pipe 44, the exhalation flow sensor F4, the sixth one-way valve C6, the manual control switch T6, the mechanical ventilation drive device 5, and the exhalation valve 6 before being discharged to the exhaust gas purification system 7. After being purified by the exhaust gas purification system 7, it is discharged.

[0078] When the airflow switch component is the fourth switch valve T8 installed on the carbon dioxide absorption branch 43, it is not necessary to open the carbon dioxide absorption tank 431 to remove the switch when calibrating the flow sensor. Simply close the fourth switch valve T8 to prevent the calibration gas from flowing through the carbon dioxide absorption branch 43 to achieve the same purpose.

[0079] like Figure 20 As shown, an embodiment of the automatic calibration system of the present invention includes a control system, a data acquisition module, a data processing module, and the aforementioned calibration gas path. The control system is connected to the calibration gas path and is used to control the output calibration gas flow rate of the calibration gas path. The data acquisition module is connected to the inspiratory flow sensor and the expiratory flow sensor in the calibration gas path, respectively, and is used to acquire the ADC values ​​output by the inspiratory flow sensor and the expiratory flow sensor. The data processing module is connected to the control system and the data acquisition module, respectively, and is used to process the data output by the control system and the data acquisition module.

[0080] like Figure 21As shown, an embodiment of a calibration method for calibrating a flow sensor using the automatic calibration system of the present invention includes the following steps: S1 builds a calibration system by connecting a standard flow sensor, an inspiratory flow sensor, and an expiratory flow sensor in series on a single airway. The S2 control system controls the standard flow sensor to output calibration gas at a standard flow rate, and acquires the ADC values ​​output by the inspiratory flow sensor and expiratory flow sensor respectively through the data acquisition module. S3 presets the flow rate gradient and adjusts the output flow rate of the standard flow sensor in sequence. It then collects the ADC values ​​output by the corresponding inspiratory flow sensor and expiratory flow sensor by sending multiple standard flow rate nodes. S4 summarizes the multiple standard flow rates set and the corresponding ADC values ​​collected by the data acquisition module to construct a "flow rate-ADC value" data table for the inspiratory flow sensor and the expiratory flow sensor. S5 uses a data fitting algorithm to fit the "flow rate-ADC value" to construct a flow rate calculation model and complete the calibration of the inspiratory flow sensor and expiratory flow sensor.

[0081] This calibration method is based on the correspondence between a standard flow rate reference and the electrical signals of the flow sensor to be calibrated (both the inspiratory and expiratory flow sensors in this invention are flow sensors to be calibrated). The standard flow sensor provides a precise and controllable constant standard flow rate. The analog-to-digital converter (ADC) output values ​​of the flow sensor to be calibrated are collected at different standard flow rates to construct a "flow rate-ADC value" data table. Then, a mathematical model is obtained through data fitting. Finally, the actual flow rate is calculated by inverting the ADC measurement value. The process of constructing the flow rate calculation model of the flow sensor to be calibrated is the calibration process. Once the flow rate calculation model of the flow sensor to be calibrated is completed, the calibration of the flow sensor to be calibrated is completed.

[0082] In step S1, the steps of setting up the calibration system include connecting the standard flow sensor and the inspiratory branch, connecting the inspiratory branch and the expiratory branch, and connecting the expiratory branch output to the outside. The calibration gas can be discharged to the outside of the anesthesia system after passing through the standard flow sensor, the expiratory branch and the inspiratory branch in sequence.

[0083] Water can be discharged through the installation port or through the exhaust gas purification system.

[0084] During the setup of the calibration system, it is necessary to ensure that the calibration gas path is well sealed and there is no gas leakage, and to ensure that the standard flow sensor, inspiratory flow sensor and expiratory flow sensor are in the same fluid environment to avoid environmental factors from interfering with the calibration accuracy.

[0085] In step S2, the standard flow rate is defined as the flow rate value displayed by the standard flow sensor, where the fluctuation range is less than a preset error range.

[0086] In this embodiment, the error value is set to ±0.1%F·S. It can be understood that other error ranges can also be set according to actual usage.

[0087] In this invention, the calibration gas flow rate of the first set of constant standard flow rate output by the standard flow sensor is denoted as F1, and the corresponding ADC value is denoted as ADC1. The data of the two are recorded and the correspondence between the standard flow rate F1 and ADC1 is established.

[0088] In step S3, multiple standard flow rate nodes cover the measurement ranges of the inspiratory flow sensor and the expiratory flow sensor.

[0089] The output flow rate of the standard flow sensor is adjusted once, and denoted as F2, F3, F4...Fn, where n≥3; for each set standard flow rate Fᵢ (i=2,3,…,n), the corresponding ADC output value ADCᵢ is recorded, and the process is repeated sequentially for F2 and ADC2, F3 and ADC3, ..., Fn. n With ADC n The corresponding data collection.

[0090] In step S5, during the fitting process, it is also necessary to select a polynomial of appropriate order based on the distribution characteristics of the data. The polynomial includes first-order, second-order, or higher-order polynomials.

[0091] By constructing a flow rate calculation model and calibrating the inspiratory and expiratory flow rate sensors, in subsequent actual measurements, it is only necessary to collect the current ADC measurement values ​​output by the inspiratory and / or expiratory flow rate sensors and substitute them into the polynomial calculation model to quickly and accurately calculate the current actual flow rate.

[0092] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not limiting. Those skilled in the art can make many specific modifications under the guidance of the present invention without departing from the spirit of the invention and the scope of protection of the claims, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A respiratory circuit flow sensor calibration gas circuit, characterized by: The device comprises a gas source module, a flow monitoring module and a breathing circuit connected in series, wherein the breathing circuit comprises an inhalation branch and an exhalation branch; The gas source module provides calibration gas for the calibration gas circuit and delivers the calibration gas to the flow monitoring module; The flow monitoring module comprises a switch valve, a proportional valve and a standard flow sensor, the standard flow sensor is connected to the inhalation branch, the switch valve is used to control the on-off of the calibration gas, and the proportional valve and the standard flow sensor are used to adjust the flow of the calibration gas and deliver the calibration gas with standard flow to the inhalation branch; The inhalation branch comprises an inhalation flow sensor, the exhalation branch comprises an exhalation flow sensor, and the inhalation branch and the exhalation branch are connected through a connecting pipeline; The calibration gas output by the flow monitoring module is discharged from the gas outlet of the exhalation branch after passing through the inhalation flow sensor and the exhalation flow sensor in sequence.

2. The calibration air path of claim 1, wherein: The device further comprises an inhalation check valve, an exhalation check valve and a carbon dioxide absorption branch, the inhalation check valve is arranged at the front end of the inhalation branch, the exhalation check valve is arranged at the rear end of the exhalation branch, and the carbon dioxide absorption device is connected to the rear end of the exhalation check valve at one end and to the front end of the inhalation check valve at the other end.

3. The calibration air path of claim 2, wherein: The exhalation branch comprises a water cup, the water cup is detachably installed between the exhalation flow sensor and the exhalation check valve, and the calibration gas is discharged from the installation opening of the water cup after being removed in sequence through the standard flow sensor, the inhalation flow sensor and the exhalation flow sensor.

4. The calibration air path of claim 2, wherein: The breathing circuit further comprises a mechanical ventilation driving device, a manual driving device and a waste gas purification system; The mechanical ventilation driving device is connected to the gas outlet of the exhalation branch at the gas inlet, and the gas outlet is connected to the waste gas purification system through an exhalation valve; The manual driving device comprises a manual machine-controlled switch valve, a manual bag and an APL valve, the manual machine-controlled switch valve is arranged on the connecting pipeline between the mechanical ventilation driving device and the exhalation branch, one end of the manual bag is connected to the exhalation branch through the manual machine-controlled switch valve, the other end is connected to the waste gas purification system through the APL valve, and the manual machine-controlled switch valve controls the switching of the gas output by the exhalation branch between the mechanical ventilation driving device and the manual bag.

5. The calibration air path of claim 4, wherein: When the inhalation flow sensor and the exhalation flow sensor are calibrated, the calibration gas is discharged to the waste gas purification system after passing through the standard flow sensor, the inhalation flow sensor, the exhalation flow sensor, the manual machine-controlled switch valve, the mechanical ventilation driving device and the exhalation valve in sequence; Or, the calibration gas is discharged to the waste gas purification system after passing through the standard flow sensor, the inhalation flow sensor, the exhalation flow sensor, the manual machine-controlled switch valve, the manual bag and the APL valve in sequence.

6. The calibration air path of claim 3 or 4, wherein: The device further comprises a calibration branch and a gas switching valve, the gas inlet of the gas switching valve is connected to the gas outlet of the flow monitoring module, the gas inlet of the calibration branch is connected to the gas outlet of the gas switching valve, and the gas outlet of the calibration branch is connected between the carbon dioxide absorption branch and the inhalation flow sensor.

7. The calibration air path of claim 6, wherein: The calibration branch outlet end is communicated between the inlet one-way valve and the inhalation flow sensor, and the calibration gas output by the gas source module is adjusted into standard flow gas by the flow monitoring module, and then discharged in sequence through the gas switching valve, the calibration branch, the inhalation flow sensor, and the exhalation flow sensor.

8. The calibration air path of claim 6, wherein: The carbon dioxide absorption branch is provided with a gas flow switching component, which prevents gas flow from passing through the carbon dioxide absorption branch when the inhalation flow sensor and the exhalation flow sensor are calibrated. The calibration branch outlet end is communicated between the carbon dioxide absorption branch and the inlet one-way valve, and the calibration gas output by the gas source module is adjusted into standard flow gas by the flow monitoring module, and then discharged in sequence through the gas switching valve, the calibration branch, the inhalation one-way valve, the inhalation flow sensor, and the exhalation flow sensor.

9. The calibration air path of claim 8, wherein: The carbon dioxide absorption branch includes a carbon dioxide absorption device and a bypass valve, the bypass valve is arranged in a bypass branch, one end of the bypass branch is communicated with the exhalation branch, and the other end is communicated with the inhalation branch, and the gas flow switching component is a switching valve arranged on the carbon dioxide absorption branch or a one-way valve arranged on the bypass branch.

10. The calibration air path of claim 4, wherein: The calibration branch outlet end is communicated between the carbon dioxide absorption branch and the inlet one-way valve, and the calibration gas output by the gas source module is adjusted into standard flow gas by the flow monitoring module, and then discharged in sequence through the gas switching valve, the calibration branch, the inhalation one-way valve, the inhalation flow sensor, and the exhalation flow sensor.

11. The calibration air path of claim 10, wherein: The carbon dioxide absorption branch is provided with a gas flow switching component, which prevents gas flow from passing through the carbon dioxide absorption branch when the inhalation flow sensor and the exhalation flow sensor are calibrated.

12. The calibration air path of any one of claims 1 to 11, characterized in that: The gas source module at least includes one of an oxygen branch and an air branch, the calibration gas is one of oxygen and air, and the gas inlet end of the gas source module is connected with external gas or internal gas.

13. An automatic calibration system characterized by: The control system, the data acquisition module, the data processing module, and the calibration gas circuit of any one of claims 1-12 are connected, and the control system is used for controlling the flow rate of the calibration gas circuit; the data acquisition module is connected with the inhalation flow sensor and the exhalation flow sensor in the calibration gas circuit, and is used for acquiring the ADC value output by the inhalation flow sensor and the exhalation flow sensor; and the data processing module is connected with the control system and the data acquisition module, and is used for processing the data output by the control system and the data acquisition module.

14. A calibration method applied to the automatic calibration system of claim 13, characterized in that, The following steps are included: S1: build a calibration system, and connect the standard flow sensor, the inhalation flow sensor, and the exhalation flow sensor in series on a gas circuit; The S2 control system controls the standard flow sensor to output the standard flow rate of the calibration gas, and collects the ADC values output by the inhalation flow sensor and the exhalation flow sensor through the data acquisition module; The S3 preset flow rate gradient adjusts the output flow rate of the standard flow sensor in sequence, and collects the corresponding ADC values output by the inhalation flow sensor and the exhalation flow sensor through the delivery of multiple standard flow rate nodes; The S4 collects the multiple standard flow rates and the corresponding ADC values collected by the data acquisition module, and constructs the "flow rate-ADC value" data table of the inhalation flow sensor and the exhalation flow sensor; The S5 adopts a data fitting algorithm to perform fitting processing on the "flow rate-ADC value", constructs a flow rate calculation model, and completes the calibration of the inhalation flow sensor and the exhalation flow sensor.

15. The calibration air path of claim 14, wherein: In the step S1, the step of building the calibration system includes connecting the standard flow sensor and the inhalation branch, connecting the inhalation branch and the exhalation branch, and connecting the output end of the exhalation branch to the outside, so that the calibration gas can be discharged to the outside of the anesthesia system through the standard flow sensor, the exhalation branch, and the inhalation branch in sequence; In the step S2, the standard flow rate is a flow rate value displayed by the standard flow sensor, and the fluctuation amplitude is less than a preset error range; In the step S3, the multiple standard flow rate nodes cover the range of the inhalation flow sensor and the exhalation flow sensor; In the step S5, the fitting processing process also needs to select a polynomial of a suitable order according to the distribution characteristics of the data, and the polynomial includes a first-order polynomial, a second-order polynomial, or a high-order polynomial.

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