CN108133653B - Human lung gas exchange simulation method and device - Google Patents

Abstract

The invention discloses a human lung gas exchange simulation method and device, which can be used for verification and production inspection of human gas exchange testing equipment. The invention simulates the human lung breathing function by controlling the movement of the cylinder piston, and simulates the gas metabolism of the human body by quantitatively releasing a specific concentration of carbon dioxide into the cylinder, with high simulation accuracy and good repeatability. At the same time, the analog output can be changed by adjusting the parameter settings of the device, which is suitable for simulating different gas metabolism rates. The invention can be used for the system calibration, inspection and verification of human respiration and gas metabolism measuring instruments, and has the advantages of simple structure and accurate and reliable results.

Description

A kind of human lung gas exchange simulation method and device

technical field

The invention relates to the field of human energy metabolism testing, in particular to a human lung gas exchange simulation method and device.

Background technique

The measurement of gas exchange in the human lungs in the resting state, that is, the resting state oxygen consumption and carbon dioxide production can be used to estimate the resting energy of the human body and the consumption rate of the three major energy substrates (carbohydrate, fat and protein). At the same time, the pulmonary gas exchange test device cooperates with load equipment such as treadmills and power cars to test the oxygen uptake and carbon dioxide output of the human body under different exercise loads. It can also be used as a tool for the assessment of cardiopulmonary function and non-invasive diagnosis of diseases. Therefore, the gas exchange test equipment is an important tool for physical health assessment and exercise ability assessment.

However, on the one hand, it is affected by many aspects such as calibration gas and equipment accuracy, sensor performance and sampling error. If there is no reliable test and verification, it is difficult to ensure the validity of the gas exchange energy metabolism test device; on the other hand, the general test process of gas metabolism is relatively long. , and the data of human gas energy metabolism changes dynamically, so it is difficult to compare and verify the same type of equipment in real person test. Therefore, it is necessary to design a corresponding simulator for the verification and inspection of this type of equipment. In recent inventions such as CN 206075672U, a breathing ventilation simulation verification device is provided, but it is still unable to simulate human oxygen consumption and carbon dioxide production, and still cannot meet the verification requirements of gas energy metabolism devices.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a human lung gas exchange simulation method and device to simulate human lung ventilation and gas metabolism exchange, which can be used for research and development verification and production inspection of human energy metabolism testing instruments.

In order to achieve the above object, the scheme adopted in the present invention is:

A human lung gas exchange simulation device, the device is composed of a soft air bag, a one-way valve, a T-joint, an electronic flow rate controller, a pressure reducing valve, and a standard gas to form a metabolic gas generating unit, which is used to simulate the gas exchange of human lungs Function, in which the pressure reducing valve is installed on the standard gas tank and connected to the electronic flow rate controller through the conduit, and the electronic flow rate controller is connected to the bottom of the soft air bag through the conduit, and one end of the check valve is installed beside the T-joint On the mouth, one end is connected to a soft air bag; a human breathing simulation unit is composed of a turntable, a first bearing, a U-shaped connecting rod, a fixed base, a second bearing, a third bearing, a straight connecting rod, a bearing guide groove, a piston and a cylinder. In order to simulate the breathing and ventilation function of human lungs, one end of the U-shaped connecting rod is fixed on the fixed base by the second bearing, and the other end is connected to the end of the straight connecting rod through the third bearing. It protrudes into the U-shaped groove in the middle of the U-shaped connecting rod. The position of the bearing guide groove is fixed. The straight connecting rod is limited by the two bearings of the bearing guide groove. The piston is located inside the cylinder. One end is connected to the straight connecting rod. A pass-through interface.

Among them, the turntable has a bar-shaped opening, the first bearing can be moved and fixed in the bar-shaped opening, and the distance r between it and the center of the turntable can be adjusted. In addition, the horizontal position of the turntable and the center of the second bearing is the same, and the vertical height is adjustable. . The stroke of the piston can be changed by adjusting the position of the first bearing and the vertical height b of the turntable.

Among them, the turntable converts the circular motion of the turntable into the linear motion of the straight connecting rod through the third bearing and the U-shaped connecting piece, and at the same time uses the bearing guide groove to limit the straight connecting rod up and down.

Among them, the one-way valve is used to isolate the soft air bag and the cylinder. When the cylinder is exhausted, the one-way valve is closed to prevent the exhaust gas from entering the soft air bag, and the standard gas is gradually accumulated in the soft air bag; , the accumulated gas in the soft air bag is sucked into the cylinder, and part of the outside air is also sucked in together.

A method for simulating human lung gas exchange, by adjusting the stroke of the cylinder to simulate different breathing and ventilation volumes of the human body; The flow controller controls the speed of the injected gas mixture to simulate different energy metabolism rates.

The beneficial effects obtained by the present invention:

1. A human lung gas exchange simulation method and device of the present invention can simulate human lung ventilation function and complex lung gas exchange by injecting a mixture of carbon dioxide and nitrogen with specific components, supplemented by a simple dynamic structure, and the The system has high accuracy and can be used for the accuracy, repeatability verification and production inspection of key measurement parameters of the human energy metabolism tester.

2. A human lung gas exchange simulation method and device of the present invention can change the ventilation volume of each breath by changing the stroke of the straight link 17, change the ventilation frequency by changing the rotation speed of the turntable 12, and change the ventilation frequency by setting the electronic flow rate controller 4. Oxygen uptake and carbon dioxide consumption per minute of analog output. Therefore, it is suitable for simulating different gas energy metabolism rates.

3. A human lung gas exchange simulation method and device of the present invention adopts a one-way valve 3 and a soft air bag 1. When the piston 8 is exhausted, the gas will not enter the soft air bag 1, so it will not affect ventilation. When the piston 8 inhales, the soft air bag 1 contracts freely. When the air in the bag is evacuated, the piston 8 can still draw air from the air into the cylinder 7. During the whole process, the pressure in the bag changes very little. , the interference to the electronic flow rate controller 4 is very small, and the accuracy of the flow rate control is ensured.

4. A human lung gas exchange simulation method and device of the present invention, the turntable 12 converts the circular motion into the linear motion of the straight connecting rod 17 through the third bearing 11 and the U-shaped connecting piece 10. Compared with the traditional crank-slider structure, the Method The adjustable travel range of the straight link is larger.

Description of drawings

1 is a schematic structural diagram of a human body breathing gas exchange simulation device of the present invention;

FIG. 2 is a schematic diagram of the principle of a human breathing gas exchange simulation device according to the present invention.

The reference numbers in the figure represent: 1. Soft air bag; 2. T-joint; 3. Check valve; 4. Electronic flow rate controller; 5. Pressure reducing valve; 6. Standard gas; 7. Cylinder; 8. Piston; 9, Bearing guide groove; 10, U-shaped connecting rod; 11, Third bearing; 12, Turntable; 13, First bearing; 14, Bar opening; 15, Second bearing; 16, Fixed base; 17, Straight connecting rod.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

A specific embodiment of the present invention A human lung gas exchange simulation device is shown in FIG. 1, including: a soft air bag 1, a T-joint 2, a one-way valve 3, an electronic flow rate controller 4, a pressure reducing valve 5, a standard Gas 6, cylinder 7, piston 8, bearing guide groove 9, U-shaped connecting rod 10, third bearing 11, turntable 12, first bearing 13, bar opening 14, second bearing 15, fixed base 16 and straight connecting rod 17.

The device is composed of a soft air bag 1, a one-way valve 3, a T-joint 2, an electronic flow rate controller 4, a pressure reducing valve 5, and a standard gas 6 to form a metabolic gas generating unit, which is used to simulate the gas exchange function of human lungs. The pressure reducing valve 5 is installed on the standard gas 6 gas tank, and is connected to the electronic flow rate controller 4 through the conduit, and the electronic flow rate controller 4 is connected to the bottom of the soft air bag 1 through the conduit, and one end of the one-way valve 3 is installed in the T type. On the side opening of the joint 2, one end is connected to the soft air bag 1; The groove 9, the piston 8 and the cylinder 7 form a human breathing simulation unit, which is used to simulate the breathing and ventilation function of the human lung. One end of the U-shaped connecting rod 10 is fixed on the fixed base 18 by the second bearing 15, and the other end is passed through the third bearing 11. Connected to the end of the straight connecting rod 17, the first bearing 13 is installed on the bar-shaped opening 14 of the turntable 12, and protrudes into the U-shaped groove in the middle of the U-shaped connecting rod 10, the position of the bearing guide groove 9 is fixed, and the straight connecting rod 17 is supported by the bearing The two bearings of the guide groove 9 are limited up and down, the piston 8 is located inside the cylinder 7, one end is connected to the straight connecting rod 17, and the outlet of the cylinder 7 is connected to a straight-through interface of the T-joint.

The turntable 12 has a bar-shaped opening 14 in which the first bearing 13 can be moved and fixed, and the distance r between it and the center of the turntable 12 can be adjusted. The height b is adjustable, and the stroke of the piston 7 can be changed by adjusting the position of the first bearing 13 and the vertical height b of the turntable 12 .

The turntable 12 converts the circular motion of the turntable 12 into the linear motion of the straight connecting rod 17 through the third bearing 11 and the U-shaped connecting piece 10 , and at the same time uses the bearing guide groove 9 to limit the straight connecting rod up and down.

The one-way valve 3 is used to isolate the soft air bag 1 and the cylinder 7. When the cylinder is exhausted, the one-way valve 3 is closed to prevent the exhaust gas from entering the soft air bag 1, and the standard gas is gradually accumulated in the soft air bag 1; When the cylinder is pumped, the accumulated gas in the soft air bag 1 is sucked into the cylinder, and part of the outside air is also sucked in together.

A human lung gas exchange simulation method, by adjusting the stroke of the cylinder 7, to simulate different breathing and ventilation volumes of the human body; by releasing a mixture of carbon dioxide and nitrogen into the cylinder to simulate the human body's gas metabolism, that is, the production of carbon dioxide and the consumption of oxygen in the human body, and by The electronic flow rate controller 4 controls the speed of the injected gas mixture to simulate different energy metabolism rates.

Simulate human body gas metabolism, that is, simulate human body carbon dioxide production and oxygen consumption. The specific calculation method is as follows: As shown in Figure 2, the pull standard piston 8 is equivalent to the "inhalation" process. There are two sources of inhalation, part of which comes from fixed components standard gas, and the other part comes from air. The standard gas intake velocity is f, the air intake velocity is g, and the CO2 concentration of the standard gas is x (the concentration of N2 is 1-x). The gas from the two sources is "inhaled" and mixed in the cylinder 7, and the gas is "exhaled" as the piston 8 pushes. Obviously, the speed of exhalation VE=f+g. The O2 and CO2 concentrations of "inhaled" air are: FiO2 and FiCO2, respectively, where FiCO2 is approximately equal to 0. The "exhaled" gas concentrations of O2 and CO2 are: FeO2 and FeCO2, respectively.

VE=f+g;

FeCO2=(f*x+g*FiCO2)/(f+g);

FeO2=g*FiO2/(f+g);

Most of the gas exchange detection equipment does not detect the inhaled gas flow. It is considered that the amount of nitrogen inhaled and exhaled by the measured human body is unchanged, and the volume of gas inhaled into the human body can be calculated:

VI=VE(1-FeO2-FeCO2)/(1-FiO2-FiCO2); (balance with N2)

VCO2=VE*FeCO2-VI*FiCO2

=VE*FeCO2-[VE(1-FeO2-FeCO2)/(1-FiO2-FiCO2)]*FiCO2

=VE*[FeCO2-FiCO2*(1-FeO2-FeCO2)/(1-FiO2-FiCO2)];

VO2=VI*FiO2-VE*FeO2

=[VE(1-FeO2-FeCO2)/(1-FiO2-FiCO2)]*FiO2-VE*FeO2

=VE*[FiO2*(1-FeO2-FeCO2)/(1-FiO2-FiCO2)-FeO2];

In fact, the CO2 concentration FiCO2 in the air can be considered to be 0, thus:

FeCO2=(f*x+g*FiCO2)/(f+g)=f*x/VE;

FeO2=g*FiO2/(f+g)=g*FiO2/VE;

VCO2=VE*[FeCO2-FiCO2*(1-FeO2-FeCO2)/(1-FiO2-FiCO2)]

=VE*FeCO2=f*x; Formula (1)

VO2=VE*[FiO2*(1-FeO2-FeCO2)/(1-FiO2-FiCO2)-FeO2]

=FiO2*f*(1-x)/(1-FiO2); Formula (2)

Usually when verifying, we take the standard gas CO2 concentration x=FiO2=21%, at this time:

VCO2=f*x=0.21*f;

VO2=FiO2*f*(1-x)/(1-FiO2)=f*FiO2=f*x=0.21f;

At this time RQ=1.

In fact, when the CO2 concentration in the air is considered to be 0, the CO2 emission VCO2=f*x, that is, the CO2 emission is actually the amount of carbon dioxide in the injected standard gas. The CO2 injected in the above simulation process is equivalent to the amount of CO2 excluded. process. This analog approach is valid for exhaled-only metabolic measurement systems, and not available for inspiratory or bidirectional gas measurement systems. The reason is that the oxygen uptake here is actually simulated and virtual, and there is no real oxygen consumption. However, for a metabolic measurement system that only detects exhalation, the inhalation concentration uses the O2 concentration of the air, and the exhalation concentration is the concentration of the gas exhausted through the cylinder 7. It can be seen from the process simulated by the above schematic diagram that the O2 concentration in the exhaled gas is The concentration is diluted by the injected standard gas, and then balanced with N2. The calculated VI is the total volume, which is larger than the volume "inhaled" from the air, thus simulating a process of oxygen uptake.

A method for simulating human lung gas exchange, the specific action process is as follows: the turntable 12 is fixed on the rotating shaft of the motor and is driven by the motor, the vertical height of the motor can be adjusted up and down, that is, the vertical distance b from the second bearing 15 can be adjusted, and the motor can be adjusted at the same time. The rotation speed can also be set and changed; the first bearing 13 is fixed on the bar-shaped opening 14 of the turntable 12, and the distance r between the two centers can be adjusted by changing the fixed position of the first bearing 13; the bottom of the U-shaped connecting rod 10 is fixed by the second bearing 15 On the fixed base 16, the turntable 12 drives the U-shaped connecting rod 10 to rotate through the first bearing 13, and is then transmitted to the straight connecting rod 17 by the third bearing 11 fixed on the straight connecting rod 17, and the straight connecting rod 17 is guided in the bearing guide. The horizontal reciprocating movement is carried out under the restriction of the groove 9, which drives the sealing piston 8 to reciprocate periodically in the cylinder 7, and the gas is inhaled and discharged from the T-joint 2, simulating the inhalation and exhaust action of human lung gas.

The standard gas 6 (mixed gas of carbon dioxide and nitrogen) is injected into the soft air bag 1 from the gas cylinder through the pressure reducing valve and the electronic flow rate controller 4, and the specific injection rate can be adjusted by setting the electronic flow rate controller 4; The air bag 1 and the equipment to be tested are connected through a T-joint 2. There is a one-way valve 3 at the opening of the T-joint 2 connected to the soft air bag 1, allowing the gas to flow from the soft air bag 1 to the outside. Therefore, during the movement of the piston 8, the one-way valve 3 is opened, and all the gas of the soft air bag 1 is sucked into the cylinder 7, and at the same time, part of the outside air is also sucked into the cylinder 7, and the exhaust gas is exhausted when the piston 8 moves. During this period, the inhaled mixed gas is discharged to the outside through the T-shaped valve.

A human lung gas exchange simulation method, the specific calculation method of the device setting parameters is as follows:

According to formula (2) and formula (3), it can be known that the output VCO2/VO2 to be simulated is only related to the concentration x of carbon dioxide in the standard gas 6, and VCO2/VO2 is called the respiratory exchange rate. The carbon dioxide concentration ratio x required in the standard gas 6, and the balance gas is nitrogen.

According to the simulated demand of carbon dioxide discharge VCO2 per minute and the concentration x of carbon dioxide in the calibration gas, the speed setting value f of the electronic flow rate controller 4 is calculated according to formula (1).

According to the simulated ventilation speed VE requirements and the cylinder inner diameter A, the rotation speed n of the turntable 12 and the round-trip distance L of the piston 8 are calculated by formula (3):

VE=f+n*(L*A) Formula (3)

The relationship between the travel distance L, the center distance r from the turntable 12 to the first bearing 13, and the vertical distance b from the turntable 12 to the second bearing 15 is:

可知:

Known:

Where: a is the vertical distance from the straight connecting rod 17 to the turntable 12 ; b is the vertical distance from the second bearing 15 to the turntable 12 . According to formula (4), it can be calculated that the distance from the first bearing 13 to be adjusted to the center of the turntable 12 is r.

A human lung gas exchange simulation device, the initial setting and starting method of the specific equipment are as follows: adjusting the fixed position of the first bearing 13 in the strip opening 14, changing the distance from the first bearing 13 to the center of the turntable 12 to be r; starting the turntable 12, set the motor speed to n; set the constant flow rate of the electronic flow rate controller 4 to f. Then, connect the device to be tested and verified through the T-type connector 2 to start the verification of the device to be tested.

A human lung gas exchange simulation device, the calculation formula of the device to simulate oxygen uptake is shown in formula (1), the error depends on the accuracy of the electronic flow rate controller and the standard gas concentration, and the electronic flow rate controller for simulating the human body oxygen uptake The range of 4 is 0 to 2L, the flow rate controller 4 with an error of less than 1% is selected, and the calibration gas with a carbon dioxide concentration error of less than 1%, the overall error of the oxygen uptake simulated by the system does not exceed 2%, and the accuracy fully meets the current human body gas. Validation requirements for metabolic devices.

Claims (2)

1. A human lung gas exchange simulation device is characterized in that: the device comprises a metabolic gas generating unit consisting of a soft air bag (1), a one-way valve (3), a T-shaped joint (2), an electronic flow rate controller (4), a pressure reducing valve (5) and standard gas (6) and is used for simulating the gas exchange function of human lungs, wherein the pressure reducing valve (5) is installed on a gas tank of the standard gas (6) and is connected to the electronic flow rate controller (4) through a conduit, the electronic flow rate controller (4) is connected to the bottom of the soft air bag (1) through the conduit, one end of the one-way valve (3) is installed on a side port beside the T-shaped joint (2), and the other end of the one-way valve is connected with the; a human body respiration simulation unit consists of a turntable (12), a first bearing (13), a U-shaped connecting rod (10), a fixed base (18), a second bearing (15), a third bearing (11), a straight connecting rod (17), a bearing guide groove (9), a piston (8) and a cylinder (7) and is used for simulating the respiration and ventilation functions of human lungs, wherein one end of the U-shaped connecting rod (10) is fixed on the fixed base (18) through the second bearing (15), the other end of the U-shaped connecting rod is connected to the tail end of the straight connecting rod (17) through the third bearing (11), the first bearing (13) is arranged on a strip-shaped opening (14) of the turntable (12) and protrudes into a U-shaped groove in the middle of the U-shaped connecting rod (10), the bearing guide groove (9) is fixed in position, the straight connecting rod (17) is vertically limited by two bearings of the bearing guide groove (9), the piston (8) is positioned in the, the outlet of the air cylinder (7) is connected with a straight-through interface of the T-shaped joint;

the rotary table (12) is provided with a strip-shaped opening (14), the first bearing (13) can move and be fixed in the strip-shaped opening (14), the distance r between the first bearing and the circle center of the rotary table (12) can be adjusted, in addition, the horizontal position of the circle center of the rotary table (12) is the same as that of the circle center of the second bearing (15), the vertical height b is adjustable, and the stroke of the piston (7) can be changed by adjusting the position of the first bearing (13) and the vertical height b of the rotary table (12);

the rotary table (12) converts the circular motion of the rotary table (12) into the linear motion of the straight connecting rod (17) through the third bearing (11) and the U-shaped connecting piece (10), and meanwhile, the bearing guide groove (9) is used for limiting the straight connecting rod up and down;

the one-way valve (3) is used for isolating the soft air bag (1) from the cylinder (7), when the cylinder exhausts, the one-way valve (3) is closed, the exhausted gas is not allowed to enter the soft air bag (1), and the standard gas is gradually accumulated in the soft air bag (1); when the cylinder is exhausted, the accumulated gas in the soft air bag (1) is sucked into the cylinder, and part of the external air is sucked together.

2. A method for simulating the exchange of gas in a human lung, using the apparatus for simulating the exchange of gas in a human lung according to claim 1, wherein: different breathing ventilation volumes of the human body are simulated by adjusting the stroke of the air cylinder (7); the carbon dioxide and nitrogen mixed gas is released into the cylinder, so that the human body gas metabolism is simulated, namely the human body carbon dioxide generation and oxygen consumption are realized, the speed of injecting the mixed gas is controlled by the electronic flow rate controller (4), and different energy metabolism rates are simulated.