A mixed cavity type human energy metabolism detection device and method

Abstract

The present invention discloses a mixing chamber type human energy metabolism detection device and method. The detection device includes a test gas circuit part, an analysis gas circuit part, a control unit and a computer. The test gas circuit is used for flow detection and collection, physical averaging, dilution and discharge of the exhaled gas of the subject; the analysis gas circuit part is used for oxygen and carbon dioxide concentration detection and sensor calibration of the subject's respiratory gas; the control unit is responsible for the control and signal acquisition of each pump and valve in the device; the computer is responsible for data collection, calculation and analysis, human-computer interaction and result display. The detection method is to first carry out gas concentration calibration, then implement metabolic testing of spontaneously breathing subjects based on gas collection hoods or mechanically ventilated subjects based on ventilators, and finally calculate and display metabolic indicators based on the measured gas component concentrations and flow parameters. The present invention can be applied to two human metabolism detection application scenarios: mechanical ventilation and spontaneous breathing. The test is safe and easy to implement in engineering.

Description

Technical Field

[0001] The present invention relates to the field of human energy metabolism detection, and in particular to a mixing chamber type human energy metabolism detection device and method. Background Art

[0002] Human energy metabolism refers to the replacement of old and new life substances in the human body and the conversion of human energy. Human energy metabolism detection is widely used in weight management, prevention and diagnosis of metabolic diseases, personalized nutritional support and other medical fields. The principle of indirect calorimetry is an internationally recognized "gold standard" for detecting human energy metabolism. It estimates energy consumption by measuring the oxygen consumption and carbon dioxide production of the human body.

[0003] At present, the main metabolic measurement methods based on indirect calorimetry are:

[0004] (1) Douglas bag method. This traditional method is achieved by collecting human respiratory gas over a period of time into a closed air bag for analysis. It has high accuracy and is regarded as the "gold standard" for measuring the accuracy of indirect energy metabolism testers. However, due to its complex operation, poor comfort and real-time performance, it is rarely used in clinical practice.

[0005] (2) Hood dilution method. When this method is used, the subject wears a gas collecting hood, and the human respiratory gas is mixed and diluted with the air in the hood and then sent to the corresponding analysis unit for flow and concentration detection to complete the calculation of metabolic indicators. It has the advantages of high comfort, simple implementation, and good accuracy, and is widely used in clinical practice. However, patients in the ICU often need to use a ventilator, nasal cannula or mask to inhale oxygen for respiratory support, and cannot use a hood. Therefore, the hood dilution method cannot support metabolic measurements of subjects under mechanical ventilation;

[0006] (3) Breath-by-breath method. This method is a monitoring method that directly collects real-time respiratory gas concentration and flow rate data without a mixing and dilution process. The flow and concentration signals of metabolic detection equipment based on this method are measured in real time. It is recognized as the best real-time method and can adapt to human energy metabolism measurement in a variety of application scenarios. However, when this method is applied to spontaneously breathing subjects, they often need to wear a mask, which makes them uncomfortable and has the risk of leakage. When applied to mechanically ventilated subjects, placing a flow sensor in the ventilator patient circuit will increase respiratory resistance and there is a risk of affecting the normal operation of the ventilator. In terms of engineering implementation, the dynamic characteristics of gas concentration sensors and the accuracy of related algorithms are extremely high. The response time of commonly used commercial sensors cannot meet the requirements, and the technical barriers to developing sensors with high precision and fast response are high, which is not easy to implement in engineering;

[0007] (4) Micro-mixing chamber method. This method collects human respiratory gas into a micro-mixing chamber through a collection device such as a breathing mask for real-time analysis, thereby realizing the calculation of metabolic indicators. The gas concentration signal is measured after physical mixing and averaging in the micro-mixing chamber, which reduces the requirements for the dynamic characteristics of the gas concentration sensor. However, like the hood dilution method, it cannot support the metabolic measurement of subjects during mechanical ventilation due to its method limitations.

[0008] In view of the shortcomings of existing human energy metabolism detection, it is necessary to design a metabolic detection device and method that is compatible with both mechanically ventilated subjects and spontaneously breathing subjects, and which does not rely on high-frequency oxygen sensors and carbon dioxide sensors in engineering implementation, does not affect the normal operation of the ventilator during testing, and can achieve accurate human energy metabolism detection with high safety and comfort. Summary of the invention

[0009] The purpose of the present invention is to propose a metabolic detection method and device suitable for two application scenarios of mechanically ventilated and spontaneously breathing subjects, which reduces the dynamic characteristics requirements of gas concentration sensors, has high safety and high comfort, and specifically relates to a mixing chamber human energy metabolism detection device and method.

[0010] In view of the above, one of the purposes of the present invention is to provide a mixing chamber type human energy metabolism detection device. The specific description is as follows:

[0011] A mixed cavity type human energy metabolism detection device, which consists of a test gas circuit part, an analysis gas circuit part, a control unit and a computer. The test gas circuit is used for flow detection and the collection, physical averaging, dilution and discharge of the subject's exhaled gas; the analysis gas circuit part is used for oxygen and carbon dioxide concentration detection of the subject's breath and calibration of oxygen sensors and carbon dioxide sensors; the control unit is responsible for the control of each pump and valve in the device and the signal collection of each sensor; the computer is responsible for data collection, calculation and analysis, human-computer interaction during testing and result display.

[0012] The test air circuit is composed of a mixing tank, an exhaust fan, a flow sensor, a main switch valve, an air collecting hood and connecting pipes. The air collecting hood is only used when testing a subject with spontaneous breathing. The exhaust fan provides negative air pressure for the test air circuit. The air outlet is connected to the ambient air, and the air inlet is connected to the air outlet of the flow sensor through an air pipe. The air inlet of the flow sensor, the air outlet of the main switch valve and the air outlet of the mixing tank are connected to each other through an air pipe tee, and the air inlet of the main switch valve is connected to the ambient air through an air circuit. The air inlet of the mixing tank collects exhaled air from the human body, and the air outlet of the mixing tank is connected to the air pipe passage between the air inlet of the flow sensor and the air outlet of the main switch valve through an air pipe. Specifically, when used on subjects with mechanical ventilation, the main switch valve is opened, the air inlet of the mixing tank is connected to the ventilator outlet pipe, and the exhaust fan extracts the mixed gas of ambient air and the exhaled air of the subject through the main switch valve and the mixing tank, and discharges it into the air; when used on subjects with spontaneous breathing, the air inlet of the mixing tank is connected to the air outlet of the air collecting hood, the air inlet of the hood is connected to the air, the main switch valve is closed, and the exhaust fan extracts the mixed gas of the exhaled air of the subject and the ambient air in the air collecting hood, and discharges it into the air. Among them, the exhaust fan acts as a negative pressure driver, and the flow sensor acts as a flow signal observer, forming a feedback PID exhaust flow control to achieve constant flow exhaust of the mixed dilution gas exhaled by the human body.

[0013] The analysis gas circuit part is composed of a gas concentration analysis unit and a gas concentration calibration unit. The gas concentration analysis unit includes a gas circuit switching module, an electronic pressure controller, an oxygen sensor, a carbon dioxide sensor, and an air pump, which is used to bypass the gas extraction sampling oxygen and carbon dioxide concentration signals; the gas concentration calibration unit includes a first high-pressure calibration gas source, a second high-pressure calibration gas source, a first pressure reducing valve, a second pressure reducing valve, a first switch valve, a second switch valve, a first three-way pressure relief device and a second three-way pressure relief device, which provide a calibration gas path for the oxygen sensor and the carbon dioxide sensor.

[0014] The gas concentration analysis unit is connected to the air pump, carbon dioxide sensor, oxygen sensor, electrical pressure controller and air path switching module in sequence through the air pipe to form a gas concentration sampling and calibration air flow path. The air pump outlet is connected to the air; the oxygen sensor and the carbon dioxide sensor are used to detect the oxygen and carbon dioxide gas concentration signals in the air flow path respectively; the electronic pressure controller is used to control the air pressure of the oxygen sensor inlet; the air path switching module has six air path interfaces a, b, c, d, e and f, the a port is connected to the air outlet of the exhaust fan or not connected, the b port is connected to the mixing tank, the c port is connected to the ambient air or the ventilator inhalation air pipeline, the d port is a common port, the e port is connected to the first group of calibration gas sources in the calibration unit, and the f port is connected to the second group of calibration gas sources in the calibration unit. The air path switching module can control the selection of five gas air flow paths of ad, bd, cd, ed and fd. Specifically, the air pump is used to provide the negative pressure of the gas concentration sampling and calibration air flow path. After the air flow in the path is stabilized by the electronic pressure controller, the gas at the d port of the air path switching module is extracted and analyzed. Specifically, when used on subjects undergoing mechanical ventilation, port A is connected to the exhaust fan outlet, port C is connected to the ventilator inhalation air circuit, and the gas circuit switching module selects to open the three gas flow paths AD, BD, and CD at different times, and samples the oxygen and carbon dioxide concentrations of the subject's exhaled mixed gas buffered by a mixing tank and diluted with ambient air, the subject's exhaled gas buffered by a mixing tank, and the ventilator inhaled gas in different times; when used on subjects undergoing spontaneous breathing, port A is not connected, port C is connected to ambient air, and the gas circuit switching module selects to open the two gas flow paths BD and CD at different times, and samples the oxygen and carbon dioxide concentrations of the subject's exhaled gas diluted by the hood and ambient air in different times.

[0015] The gas concentration calibration unit is connected in sequence through an air pipe to a first high-pressure calibration gas source, a first pressure reducing valve, a first switch valve, a first three-way pressure relief device and an e port of an air path switching module to form a first group of calibration air flow paths, and a second high-pressure calibration gas source, a second pressure reducing valve, a second switch valve, a second three-way pressure relief device and an f port of an air path switching module to form a second group of calibration air flow paths, providing two types of calibration air flow paths for the oxygen sensor and the carbon dioxide sensor in the gas concentration analysis unit. Specifically, when the first set of calibration gas is used to calibrate the concentration of the oxygen sensor and the carbon dioxide sensor in the gas concentration analysis unit, the first high-pressure calibration gas source is first opened, and then the calibration gas is decompressed by the first pressure reducing valve to the first switch valve, then the first switch valve is opened, and finally the calibration gas is decompressed by the first three-way pressure relief device to the e port of the gas path switching module; when the second set of calibration gas is used to calibrate the concentration of the oxygen sensor and the carbon dioxide sensor in the gas concentration analysis unit, the second high-pressure calibration gas source is first opened, and then the calibration gas is decompressed by the second pressure reducing valve to the second switch valve, then the second switch valve is opened, and finally the calibration gas is decompressed by the second three-way pressure relief device to the f port of the gas path switching module. Preferably, the volume percentage of the first high-pressure calibration gas source is 60% oxygen and 40% nitrogen; the volume percentage of the second high-pressure calibration gas source is 16% oxygen, 5% carbon dioxide, and 79% nitrogen.

[0016] The second object of the present invention is to provide a mixed chamber human energy metabolism detection method. Based on the above detection device, the specific steps are described as follows:

[0017] Step 1: The operator carries out gas concentration calibration of the oxygen sensor and the carbon dioxide sensor. First, when calibrating the first group of gases, the first high-pressure calibration gas source and the first switch valve are opened, and the gas circuit switching module selects to open the ed airflow path, and the high-pressure gas source is first decompressed by the first pressure reducing valve, and then decompressed by the first three-way pressure relief device and sent to the e port of the gas circuit switching module, so as to realize the first group of calibration airflow paths, ventilate and wait for the airflow to stabilize, collect the average gas concentration over a period of time, and complete the range point calibration of the oxygen sensor and the zero point calibration of the carbon dioxide sensor; then, when calibrating the second group of gases, the second high-pressure calibration gas source and the second switch valve are opened, and the high-pressure gas source is first decompressed by the second pressure reducing valve, and then decompressed by the second three-way pressure relief device and sent to the f port of the gas circuit switching module, so as to realize the second group of calibration airflow paths, ventilate and wait for the airflow to stabilize, collect the average gas concentration over a period of time, and complete the zero point calibration of the oxygen sensor and the range point calibration of the carbon dioxide sensor. Finally, close each high-pressure calibration gas source and valve to end the gas concentration calibration of the oxygen sensor and the carbon dioxide sensor;

[0018] Step 2: The subject completes user registration and login on the computer, makes preparations for the metabolic test, and starts the test.

[0019] When used on subjects with mechanical ventilation: the main switch valve is opened, port a is connected to the exhaust fan outlet, port c is connected to the ventilator inhalation air pipeline, and the air inlet end of the mixing tank is connected to the ventilator outlet through the ventilator pipeline. The exhaled air of the subject is discharged into the mixing tank through the ventilator exhalation port. After the gas concentration in the mixing tank is physically averaged, it is extracted and discharged into the air together with the air at the inlet end of the main switch valve. The gas path switching module selects to open the three gas flow paths of ad, bd, and cd in a time-sharing manner. The gas concentration analysis unit samples the carbon dioxide concentration of the subject's exhaled mixed gas buffered by the mixing tank and diluted with ambient air, the oxygen and carbon dioxide concentration of the subject's exhaled gas buffered by the mixing tank, and the oxygen concentration of the ventilator's inhaled gas in a time-sharing manner.

[0020] When used on subjects with spontaneous breathing: the main switch valve is closed, port a is not connected, port c is connected to ambient air, the subject wears a gas collecting hood, the air inlet of the gas collecting hood is connected to air, and the air outlet of the gas collecting hood is connected to the air inlet of the mixing tank through the ventilator pipeline. The exhaled gas of the subject in the gas collecting hood is mixed with air and then extracted into the mixing tank. After the gas concentration in the mixing tank is physically averaged, it is discharged into the air through the exhaust fan. The gas path switching module selects to open the two gas flow paths bd and cd in a time-sharing manner, and the gas concentration analysis unit samples the oxygen and carbon dioxide concentrations of the exhaled gas of the subject diluted by the hood and the ambient air in turn in a time-sharing manner.

[0021] Step 3: The computer calculates the metabolism-related indicators: oxygen uptake rate, carbon dioxide production rate based on the data collected and uploaded by the control unit. The formula derivation is expressed as follows:

[0022] Carbon dioxide production rate (VCO2):

[0023] (1)

[0024] Oxygen uptake rate (VO2):

[0025] (2)

[0026] Respiratory Quotient (RQ):

[0027] (3)

[0028] Among them, FeCO2 is the carbon dioxide concentration of the subject's exhaled air (%); FiCO2 is the carbon dioxide concentration of the subject's inhaled air (%). Generally, the carbon dioxide concentration in air or ventilator inhaled gas is extremely low, and the default value is 0; Ve is the flow rate of exhaled air (L / Min); Vi is the flow rate of inhaled air (L / Min); FiO2 is the oxygen concentration of the subject's inhaled air (%); FeO2 is the oxygen concentration of the subject's exhaled air (%).

[0029] Because the molecular weight of inert gases such as nitrogen does not participate in the exchange when the human body breathes, the molecular weight of nitrogen in the inhaled and exhaled air is equal, so for the breathing process, equation (4) holds.

[0030] (4)

[0031] When used in mechanically ventilated subjects:

[0032] Carbon dioxide is only produced by the human body. The carbon dioxide production rate can be obtained by sampling after air dilution treatment at the mixing tank buffer and main switch valve, that is:

[0033] Carbon dioxide production rate (VCO2):

[0034] (5)

[0035] Where FdCO2 is the carbon dioxide concentration (%) of the exhaled mixed gas of the subject after buffering in the mixing tank and diluting with ambient air; Q is the constant extraction flow rate (L / Min) of the exhaust fan.

[0036] Combining equations (1), (2), (3) and (4) we can get:

[0037] (6)

[0038] According to the transformation of formula (3), the oxygen uptake rate (VO2) is:

[0039] ;

[0040] When used in spontaneously breathing subjects:

[0041] Combining equations (1), (2), (3) and (4) we can get:

[0042] Carbon dioxide production rate (VCO2):

[0043] (7)

[0044] Oxygen uptake rate (VO2):

[0045] (8)

[0046] Beneficial effects achieved by the present invention:

[0047] 1. The present invention realizes the measurement of human energy metabolism of subjects with spontaneous breathing based on a hood and subjects under mechanical ventilation based on a ventilator through a test gas circuit controlled by a main switch valve;

[0048] 2. The present invention physically averages the exhaled air of the human body through a mixing tank and physically dilutes the exhaled air of the human body through the ambient air at the main switch valve, thereby reducing the dynamic performance requirements for the oxygen sensor and the carbon dioxide sensor, making human metabolism detection and analysis easier to implement in engineering;

[0049] 3. The present invention detects human energy metabolism by collecting exhaust gas from a ventilator, rather than sampling human respiratory gas in a bypass channel of the ventilator's patient circuit to detect human energy metabolism, thereby avoiding interference with the operation of the ventilator and making the detection of human energy metabolism of subjects under mechanical ventilation safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of a mixing chamber type human energy metabolism detection device of the present invention;

[0051] Figure 2 This is a schematic diagram of the structure of the connection between the metabolic detection device of the present invention and the metabolic detection device during the metabolic test of a subject undergoing mechanical ventilation;

[0052] Figure 3 It is a schematic diagram of the structure of connection between a spontaneously breathing subject and the metabolic detection device of the present invention during metabolic testing.

[0053] The names of the reference numerals are: 1-exhaust fan, 2-flow sensor, 3-main switch valve, 4-mixing tank, 5-gas path switching module, 6-electronic pressure controller, 7-oxygen sensor, 8-carbon dioxide sensor, 9-exhaust pump, 10-first three-way pressure relief device, 11-first switch valve, 12-first pressure reducing valve, 13-second three-way pressure relief device, 14-second switch valve, 15-second pressure reducing valve, 16-second high-pressure calibration gas source, 17-first high-pressure calibration gas source, 18-ventilator, 19-gas collecting hood. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0055] See also Figure 1 This embodiment provides a mixing chamber type human energy metabolism detection device, including a test gas circuit part, an analysis gas circuit part, a control unit and a computer.

[0056] The test gas circuit part is composed of a mixing tank 4, an exhaust fan 1, a flow sensor 2, a main switch valve 3 and a connecting pipeline. The exhaust fan 1 is connected to the ambient air at its outlet, and its inlet is connected to the outlet of the flow sensor 2 through an air pipe; the inlet of the flow sensor 2, the outlet of the main switch valve 3 and the outlet of the mixing tank 4 are connected to each other through an air pipe tee, and the inlet of the main switch valve 3 is connected to the ambient air through an air circuit; the inlet of the mixing tank 4 collects exhaled air from the human body, and the outlet of the mixing tank 4 is connected to the air pipe passage between the inlet of the flow sensor 2 and the outlet of the main switch valve 3 through an air pipe. Preferably, the mixing tank 4 is a 3L cavity.

[0057] The exhaust fan 1 is a negative pressure generator, and the flow sensor 2 is a flow signal observer, which constitutes and executes feedback PID exhaust flow control to achieve constant flow exhaust of the mixed dilution gas exhaled by the human body. Preferably, the constant flow is set to 50L / Min.

[0058] The analysis gas path part is composed of a gas concentration analysis unit and a gas concentration calibration unit. The gas concentration analysis unit includes a gas path switching module 5, an electronic pressure controller 6, an oxygen sensor 7, a carbon dioxide sensor 8, and an air pump 9, which are used to bypass the gas extraction sampling oxygen and carbon dioxide concentration signals; the gas concentration calibration unit includes a first high-pressure calibration gas source 17, a second high-pressure calibration gas source 16, a first pressure reducing valve 12, a second pressure reducing valve 15, a first switch valve 11, a second switch valve 14, a first three-way pressure relief device 10 and a second three-way pressure relief device 13, which provide a calibration gas path for the oxygen sensor 7 and the carbon dioxide sensor 8.

[0059] The gas concentration analysis unit is connected to the air pump 9, the carbon dioxide sensor 8, the oxygen sensor 7, the electrical pressure controller 6 and the air path switching module 5 in sequence through the air pipe to form a gas concentration sampling and calibration air flow path. The air pump 9 is connected to the air outlet; the electronic pressure controller 6 is used to control the air pressure of the oxygen sensor 7 inlet; the air path switching module 5 has six air path interfaces a, b, c, d, e and f, the a port is connected to the air outlet of the air exhaust fan 1 or not connected, the b port is connected to the mixing tank 4, the c port is connected to the ambient air or the inhalation air pipeline of the ventilator, the d port is a common port, the e port is connected to the first group of calibration air flow paths in the calibration unit, and the f port is connected to the second group of calibration air flow paths in the calibration unit. The air path switching module 5 can control the selection of five gas air flow paths, namely ad, bd, cd, ed and fd. Specifically, the air pump 9 is used to provide a negative pressure for the gas concentration sampling and calibration air flow path. After the air flow in the path is stabilized by the electronic pressure controller 6, the gas at the d port of the air path switching module 5 is extracted and analyzed. Preferably, the gas flow rate of the sampling calibration gas flow passage is set and controlled at 180 mL / Min by the electronic pressure controller 6 .

[0060] The gas concentration calibration unit is connected in sequence through an air pipe to form a first set of calibration gas flow paths by connecting the first high-pressure calibration gas source 17, the first pressure reducing valve 12, the first switch valve 11, the first three-way pressure relief device 10 and the gas path switching module 5 e port, and the second set of calibration gas flow paths is formed by the second high-pressure calibration gas source 16, the second pressure reducing valve 15, the second switch valve 14, the second three-way pressure relief device 13 and the gas path switching module 5 f port, providing two calibration gas flow paths for the oxygen sensor 7 and the carbon dioxide sensor 8 in the gas concentration analysis unit. Preferably, the gas volume percentage of the first high-pressure calibration gas source 17 is 60% oxygen and 40% nitrogen; the gas volume percentage of the second high-pressure calibration gas source 16 is 16% oxygen, 5% carbon dioxide, and 79% nitrogen.

[0061] A mixed cavity type human energy metabolism detection method, specifically comprising the following steps:

[0062] Step 1: The operator carries out gas concentration calibration of the oxygen sensor 7 and the carbon dioxide sensor 8. First, during the first group of gas calibration, the first high-pressure calibration gas source 17 and the first switch valve 11 are opened, and the gas circuit switching module 5 selects to open the ed airflow path, and the high-pressure gas source is first decompressed by the first pressure reducing valve 12, and then decompressed by the first three-way pressure relief device 10 and sent to the e port of the gas circuit switching module 5, so as to realize the first group of calibration airflow paths, and complete the range point calibration of the oxygen sensor 7 and the zero point calibration of the carbon dioxide sensor 8 after ventilation for a period of time; then, during the second group of gas calibration, the second high-pressure calibration gas source 16 and the second switch valve 14 are opened, and the high-pressure gas source is first decompressed by the second pressure reducing valve 15, and then decompressed by the second three-way pressure relief device 13 and sent to the f port of the gas circuit switching module 5, so as to realize the second group of calibration airflow paths, and complete the zero point calibration of the oxygen sensor 7 and the range point calibration of the carbon dioxide sensor 8 after ventilation for 1 minute. Finally, close each high-pressure calibration gas source and valve to end the gas concentration calibration of the oxygen sensor 7 and the carbon dioxide sensor 8;

[0063] Step 2: The subject completes user registration and login on the computer, makes preparations for the metabolic test, and starts the test.

[0064] See also Figure 2, when applied to metabolic testing of mechanically ventilated subjects: the main switch valve 3 is opened, port a is connected to the exhaust fan 1 outlet, port c is connected to the ventilator 18 inhalation air pipeline, and the air inlet end of the mixing tank 4 is connected to the ventilator 18 outlet through the ventilator pipeline. The exhaled air of the subject is discharged into the mixing tank 4 through the exhalation port of the ventilator 18, and after the physical averaging of the gas concentration in the mixing tank, it is extracted and discharged into the air together with the air at the inlet end of the main switch valve 3. The gas path switching module 5 selects to open the three gas flow paths of ad, bd, and cd in a time-sharing manner, and the gas concentration analysis unit samples the carbon dioxide concentration of the subject's exhaled mixed gas buffered by the mixing tank 4 and diluted with ambient air, the oxygen and carbon dioxide concentration of the subject's exhaled gas buffered by the mixing tank 4, and the oxygen concentration of the ventilator inhaled gas in a time-sharing manner.

[0065] See also Figure 3 , when applied to metabolic testing of spontaneously breathing subjects: the main switch valve 3 is closed, port a is not connected, port c is connected to ambient air, the subject wears an air collecting hood 19, the air inlet of the air collecting hood 19 is connected to air, and the air outlet of the air collecting hood 19 is connected to the air inlet end of the mixing tank 4 through a ventilator pipeline. The exhaled gas of the subject in the air collecting hood 19 is mixed with air and then extracted into the mixing tank 4, and after the gas concentration in the mixing tank is physically averaged, it is discharged into the air through the exhaust fan. The gas path switching module 5 selects to open the two gas flow paths bd and cd in a time-sharing manner, and the gas concentration analysis unit sequentially samples the oxygen and carbon dioxide concentrations of the exhaled gas of the subject and the ambient air diluted by the hood in a time-sharing manner;

[0066] Step 3: The computer calculates the metabolism-related indicators: oxygen uptake rate, carbon dioxide production rate based on the data collected and uploaded by the control unit. The calculation formula is as follows:

[0067] When used in mechanically ventilated subjects:

[0068] Carbon dioxide production rate (VCO2): ;

[0069] Respiratory Quotient (RQ): ;

[0070] Oxygen uptake rate (VO2): ;

[0071] When used in spontaneously breathing subjects:

[0072] Carbon dioxide production rate (VCO2): ;

[0073] Oxygen uptake rate (VO2): ;

[0074] Respiratory Quotient (RQ): ;

[0075] Among them, FdCO2 is the carbon dioxide concentration of the mixed gas exhaled by the subject after buffering in the mixing tank and diluting with ambient air; Q is the constant extraction flow rate of the exhaust fan; FeO2 is the oxygen concentration of the exhaled gas of the subject; FeCO2 is the carbon dioxide concentration of the exhaled gas of the subject; FiO2 is the oxygen concentration of the inhaled gas of the subject.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A mixing chamber type human energy metabolism detection device, characterized in that: It includes a test gas circuit part, an analysis gas circuit part, a control unit and a computer; The test gas circuit part is used for flow detection and collection, physical averaging, dilution and discharge of the exhaled air of the subject; The analytical gas circuit part is used for detecting the oxygen and carbon dioxide concentrations of the subject's breath and calibrating the oxygen sensor and the carbon dioxide sensor; The control unit is responsible for controlling each pump and valve in the device and collecting signals from each sensor; The computer is responsible for data collection, calculation and analysis, human-computer interaction during testing and result display; the test air circuit part is composed of a mixing tank (4), an exhaust fan (1), a flow sensor (2), a main switch valve (3) and a connecting pipeline; the exhaust fan (1) is connected to the ambient air at its outlet end, and its inlet end is connected to the outlet end of the flow sensor (2) via an air pipe; the inlet end of the flow sensor (2), the outlet end of the main switch valve (3) and the outlet end of the mixing tank (4) are connected to each other via an air pipe tee, and the inlet end of the main switch valve (3) is connected to the ambient air via an air circuit; the inlet of the mixing tank (4) collects exhaled air from the human body, and the outlet of the mixing tank (4) is connected to the air pipe passage between the inlet end of the flow sensor (2) and the outlet end of the main switch valve (3) via an air pipe; The analysis gas path portion is composed of a gas concentration analysis unit and a gas concentration calibration unit. The gas concentration analysis unit comprises a gas path switching module (5), an electronic pressure controller (6), an oxygen sensor (7), a carbon dioxide sensor (8), and an air pump (9), and is used for bypassing the gas extraction sampling oxygen and carbon dioxide concentration signals; the gas concentration calibration unit comprises a first high-pressure calibration gas source (17), a second high-pressure calibration gas source (16), a first pressure reducing valve (12), a second pressure reducing valve (15), a first switch valve (11), a second switch valve (14), a first three-way pressure relief device (10), and a second three-way pressure relief device (13), and provides a calibration gas path for the oxygen sensor (7) and the carbon dioxide sensor (8); The gas concentration analysis unit is connected in sequence via an air pipe to an air pump (9), a carbon dioxide sensor (8), an oxygen sensor (7), an electronic pressure controller (6) and an air path switching module (5), thereby forming an air flow path for gas concentration sampling and calibration; the air outlet of the air pump (9) is connected to air; the electronic pressure controller (6) is used to control the air pressure at the air inlet of the oxygen sensor (7); the air path switching module (5) has six air path interfaces a, b, c, d, e and f, the a port is connected to the air outlet of the air exhaust fan (1) or is not connected, and the b port is connected to The mixing tank (4) has a port c connected to ambient air or a breathing machine inhalation air pipeline, a port d being a common port, a port e connected to a first group of calibration airflow paths in a calibration unit, and a port f connected to a second group of calibration airflow paths in a calibration unit. The air path switching module (5) can control and select five gas airflow paths, namely ad, bd, cd, ed, and fd. The air pump (9) is used to provide a negative pressure for the gas concentration sampling calibration airflow path. After the airflow in the path is stabilized by the electronic pressure controller (6), the gas at the port d of the air path switching module (5) is extracted and analyzed. The gas concentration calibration unit is a first group of calibration gas flow paths formed by sequentially connecting a first high-pressure calibration gas source (17), a first pressure reducing valve (12), a first switch valve (11), a first three-way pressure relief device (10) and an e port of a gas path switching module (5) through a gas pipe, and a second group of calibration gas flow paths formed by connecting a second high-pressure calibration gas source (16), a second pressure reducing valve (15), a second switch valve (14), a second three-way pressure relief device (13) and an f port of a gas path switching module (5), thereby providing two calibration gas flow paths for an oxygen sensor (7) and a carbon dioxide sensor (8) in the gas concentration analysis unit.

2. The device according to claim 1, characterized in that The exhaust fan (1) is a negative air pressure generator, and the flow sensor (2) is a flow signal observer, which form and execute feedback PID exhaust flow control to achieve constant flow exhaust of the mixed dilution gas exhaled by the human body.

3. A detection method of the mixing chamber type human energy metabolism detection device according to claim 1 or 2, characterized in that: The method comprises the following steps: Step 1: The operator performs gas concentration calibration of the oxygen sensor (7) and the carbon dioxide sensor (8); first, during the first group of gas calibration, the first high-pressure calibration gas source (17) and the first switch valve (11) are opened, and the gas path switching module (5) selects to open the ed gas flow path, and the high-pressure gas source is first depressurized by the first pressure reducing valve (12), and then depressurized by the first three-way pressure relief device (10) and then sent to the e port of the gas path switching module (5), so as to realize the first group of calibration gas flow paths, and after the gas flow is ventilated and stabilized, the gas concentration average value within a period of time is collected to complete the range point calibration of the oxygen sensor (7) and the carbon dioxide sensor (8 ) zero point calibration; then, when the second group of gas is calibrated, the second high-pressure calibration gas source (16) and the second switch valve (14) are opened, the high-pressure gas source is first depressurized by the second pressure reducing valve (15), and then depressurized by the second three-way pressure relief device (13) before being sent to the f port of the gas path switching module (5), so as to realize the second group of calibration gas flow path, ventilate and wait for the gas flow to stabilize, collect the average gas concentration over a period of time to complete the zero point calibration of the oxygen sensor (7) and the range point calibration of the carbon dioxide sensor (8); finally, close each high-pressure calibration gas source and valve, and end the gas concentration calibration of the oxygen sensor (7) and the carbon dioxide sensor (8); Step 2: The subject completes user registration and login on the computer, makes preparations before the metabolic test, and starts the test; When used on a subject undergoing mechanical ventilation: the main switch valve (3) is opened, port a is connected to the outlet of the exhaust fan (1), port c is connected to the inhalation air pipeline of the ventilator, and the inlet end of the mixing tank (4) is connected to the outlet of the ventilator through the ventilator pipeline; the exhaled air of the subject is discharged into the mixing tank (4) through the exhalation air outlet of the ventilator, and after the gas concentration of the mixing tank is physically averaged, it is extracted together with the air at the inlet end of the main switch valve (3) and discharged into the air, the gas path switching module (5) selects to open three gas flow paths ad, bd, and cd in a time-sharing manner, and the gas concentration analysis unit sequentially samples the carbon dioxide concentration of the exhaled mixed gas of the subject buffered by the mixing tank (4) and diluted with ambient air, the oxygen and carbon dioxide concentrations of the exhaled gas of the subject buffered by the mixing tank (4), and the oxygen concentration of the inhaled gas of the ventilator in a time-sharing manner; When used on a subject who is breathing spontaneously: the main switch valve (3) is closed, port a is not connected, port c is connected to ambient air, the subject wears an air collecting hood, the air inlet of the air collecting hood is connected to air, and the air outlet of the air collecting hood is connected to the air inlet of the mixing tank (4) through a ventilator pipeline. The exhaled air of the subject in the air collecting hood is mixed with air and then drawn into the mixing tank (4), and after the gas concentration in the mixing tank is physically averaged, it is discharged into the air through an exhaust fan; the gas path switching module (5) selects to open the two gas flow paths bd and cd in a time-sharing manner, and the gas concentration analysis unit sequentially samples the oxygen and carbon dioxide concentrations of the exhaled air of the subject diluted by the hood and the ambient air in a time-sharing manner; Step 3: The computer calculates the metabolism-related indicators based on the data collected and uploaded by the control unit: oxygen uptake rate, carbon dioxide production rate; the calculation formula is as follows: When used in mechanically ventilated subjects: Carbon dioxide production rate VCO2: ; Respiratory Quotient RQ: ; Oxygen uptake rate VO2: ; When used in spontaneously breathing subjects: Carbon dioxide production rate VCO2: ; Oxygen uptake rate VO2: ; Respiratory Quotient RQ: ; Among them, FdCO2 is the carbon dioxide concentration of the mixed gas exhaled by the subject after buffering in the mixing tank and diluting with ambient air; Q is the constant extraction flow rate of the exhaust fan; FeO2 is the oxygen concentration of the exhaled gas of the subject; FeCO2 is the carbon dioxide concentration of the exhaled gas of the subject; FiO2 is the oxygen concentration of the inhaled gas of the subject.

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