Method for constructing tension calculation model of inert gas in human tissue

Abstract

The invention discloses a method for constructing a tension calculation model of inert gas in human tissues. The method comprises the following steps of: establishing a pressure change rate function of a certain tissue of a human body and performing form transformation to obtain a corresponding first-order inhomogeneous linear differential equation; constructing a standard form and a general solution form of a first-order inhomogeneous linear differential equation; the first-order inhomogeneous linear differential equation and the general solution form thereof are correspondingly assigned and substituted into the general solution form to obtain a general human body certain tissue pressure function; respectively constructing a pressure function g1 (x) of a certain tissue of the human body in a respiratory gas index pressurization scene, a pressure function g2 (x) of a certain tissue of the human body in a linear decompression scene and a pressure function g3 (x) of a certain tissue of the human body in a linear pressurization scene by using a universal pressure function of a certain tissue of the human body; and respectively constructing inert gas tension calculation models G1 (x), G2 (x) and G3 (x) of a certain tissue of the human body under the scenes of index pressurization, linear decompression and linear pressurization by using the g1 (x), g2 (x) and g3 (x) and the inert gas percentage content d.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of model construction, in particular to a method for constructing a model for calculating inert gas tension in human tissue. BACKGROUND

[0002] Diving (a person submerges below the water surface, reaches a certain depth, stays for a period of time, and then rises out of the water, which is called diving), as a means of struggle between human beings and nature, has begun in the primitive age of human beings. With the needs of production struggle, class struggle, scientific experiments, and the continuous improvement of industrial technology, diving technology has been increasingly widely applied and developed, and has become a specialized technology.

[0003] Diving has become an indispensable technology in economic construction, national defense construction, scientific research, and military operations, and shoulders many important tasks in military and civilian aspects. For example: rescue diving, salvage of sunken ships (objects), sea rescue, underwater exploration, underwater construction (laying of pipelines, cables, construction of military port wharfs, underwater special projects and facilities), cleaning of waterways, underwater reconnaissance and blasting, underwater supply, bridge construction, aquaculture, reservoir maintenance, underwater resource exploration and development (oil, natural gas, mineral resources), marine scientific research, etc., all of which require a large amount of diving operations.

[0004] The atmospheric pressure that a person bears at normal pressure is 1 ata, at 10 m underwater (here refers to seawater, and 10.3 m for freshwater), the human body bears 1 ata of atmospheric pressure and 1 ata of hydrostatic pressure, and the total environmental pressure is 2 ata; at 20 m underwater, the human body bears 1 ata of atmospheric pressure and 2 ata of hydrostatic pressure, and the total environmental pressure is 3 ata, and so on. As can be seen, during the process of diving operation, a person must breathe compressed air to balance the pressure inside and outside the body due to the simultaneous bearing of atmospheric pressure and hydrostatic pressure at the corresponding depth, and thus is in a high-pressure environment.

[0005] As for breathing air, its main components are oxygen, carbon dioxide, and nitrogen. When breathing compressed air at high pressure, the content of oxygen and carbon dioxide usually does not change much (except for "oxygen poisoning" in the case of excessively high oxygen partial pressure or "carbon dioxide poisoning" due to special accidents) due to the special adjustment function of the body. Nitrogen, as the largest component of air, is the most common inert gas (low chemical activity, does not participate in the metabolism of the body, is not utilized by the body, and exists in the body only in a simple physical dissolved state) encountered in conventional air diving (such as nitrogen, helium, neon, argon, krypton, xenon, etc.). However, the human body cannot utilize nitrogen, and there is no mechanism to regulate the content of nitrogen, and the amount of nitrogen dissolved in the body increases with the increase of nitrogen partial pressure of inhaled air, and decreases with the decrease of nitrogen partial pressure. This feature causes special problems in diving medicine.

[0006] When the body is in a high pressure environment, inert gas is constantly dissolving in various tissues in the body. With the passage of time, the total amount of inert gas dissolved in the tissues gradually increases until it reaches an equilibrium state, i.e. the amount of gas entering and leaving the tissues is equal. In this way, a certain inert gas reaches a state where it cannot increase the amount of dissolution in the tissues under a certain pressure, which is called "saturation" of the gas in the tissues under this pressure.

[0007] When the pressure drops from high to low, the amount of inert gas dissolved in the tissues at high pressure exceeds the maximum amount of dissolution of the gas in the tissues under lower pressure, but the excess part of the inert gas is still dissolved in the tissues, which is called "supersaturation".

[0008] When the tension of the inert gas dissolved in the tissues is higher than the external air pressure, the inert gas will be released from the tissues to gradually balance the tension of the inert gas in the tissues with the external air pressure, which is called "desaturation".

[0009] The process of saturation and desaturation of inert gas in the tissues is completed through the respiratory and blood circulation systems.

[0010] When breathing compressed air, the nitrogen partial pressure in the alveoli also rises accordingly. When the blood flows through the alveoli, nitrogen dissolves into the blood according to the pressure difference between it and the nitrogen tension in the blood, and the nitrogen tension in the blood also rises. The blood saturated with a certain amount of nitrogen flows to the tissues, and the nitrogen tension in the blood is higher than that in the tissues, so nitrogen diffuses from the blood to the tissues. When the blood flows back from the tissues to the alveoli, nitrogen in the alveoli again dissolves into the blood. This cycle continues. Finally, the nitrogen partial pressure in the alveoli and the nitrogen tension in the blood and tissues tend to be in equilibrium, i.e. complete saturation is reached. This process is called the saturation process of nitrogen.

[0011] When the ambient pressure is reduced to a certain level, the partial pressure of nitrogen in the alveoli is reduced accordingly. The tension of dissolved nitrogen in the blood is higher than the partial pressure of nitrogen in the alveoli (supersaturation of nitrogen in the blood), so nitrogen diffuses from the blood into the alveoli (desaturation of nitrogen in the blood). When this part of blood flows back to the tissues, the tension of nitrogen previously dissolved in the tissues is higher than that in the blood, so nitrogen continues to diffuse from the tissues into the blood (desaturation of nitrogen in the tissues). The blood circulates again to the alveoli, and the nitrogen brought from the tissues diffuses again into the alveoli. This process is called the desaturation process of nitrogen. This process is repeated until the nitrogen tension in the tissues and the partial pressure of nitrogen in the alveoli gradually reach equilibrium, i.e. complete desaturation. It should be noted that this is a form of desaturation, i.e. the gas in the dissolved state circulates through the blood and respiratory system, gradually diffuses from the tissues, and finally leaves the body through the alveoli. Such desaturation does not harm the body, so it is called "safe desaturation". The decompression that can cause inert gas "safe desaturation" is called "safe decompression". Another form of desaturation is that the reduction of ambient pressure exceeds the safe decompression range, so that the tension of dissolved inert gas in the tissues and blood exceeds the ambient pressure too much, and the dissolved inert gas in the tissues and blood, i.e. "in situ", escapes to form bubbles, which can cause "decompression sickness".

[0012] Decompression sickness is a disease in which the body is exposed to a certain pressure environment for a certain period of time, and the external pressure is reduced too quickly and too greatly, which is enough to make the originally dissolved inert gas in the body tissues escape into the gaseous phase to form bubbles, leading to a series of pathological reactions.

[0013] It mainly occurs in the following situations: (1) diving operations (including simulated diving in dry and wet hyperbaric chambers); (2) high pressure (caisson, tunnel) operations; (3) submarine crew members from a sunken submarine escaping from the sea bottom; (4) flight personnel riding non-pressurized cabins, or simulating flight ascent to high altitude in low pressure chambers, or in high altitude pressurized cabins with closed failure; (5) high pressure oxygen therapy chamber work, etc.

[0014] In order to prevent the occurrence of decompression sickness as much as possible, it is necessary to study the rules of inert gas saturation and desaturation in human tissues. When the body is exposed to a high pressure environment, the nitrogen tension difference between the alveoli and the tissues is the largest, and the nitrogen saturation rate is the fastest; then, as the process of nitrogen saturation in the tissues gradually develops, the nitrogen tension also increases, and the nitrogen partial pressure difference between the alveoli and the tissues gradually decreases. In addition, when the body is saturated at high pressure, the nitrogen partial pressure difference between the tissues and the alveoli is the largest at the moment of decompression, and the desaturation rate is the fastest; then, as the decompression and desaturation of nitrogen in the tissues, the nitrogen tension decreases, and the nitrogen partial pressure difference between the tissues and the alveoli gradually decreases. Therefore, it can be seen that the saturation and desaturation rates of nitrogen in the body are not the same at different stages, but decrease with the decrease of the nitrogen partial pressure difference between the alveoli and the tissues.

[0015] The various tissue components of the human body are different from each other, and the blood distribution also has great differences. Therefore, the inert gas saturation speed of different tissues is different. In order to be convenient for application, Haldane roughly classifies the whole body tissue into five categories according to the time required to reach half saturation based on the air diving depth (60m or less) and the underwater exposure time and the corresponding experimental data at that time. The classification of the tissue is assumed, so it is called "theoretical tissue". The half saturation time of the five theoretical tissues is 5min, 10min, 20min, 40min and 75min respectively, and the mathematical model is actually: S=(1-0.5 t )×100%, wherein S is the saturation, and t is the assumed time unit. This mathematical model is most suitable for calculating the underwater stay stage, that is, when a person maintains at a certain depth of water, the environmental pressure remains unchanged. The problem is that the change of environmental pressure is continuous, and the person cannot directly be in the water pressure of a certain depth or instantaneously out of the environment of a certain depth.

[0016] The current mathematical model cannot calculate the way in which the environmental pressure increases in some form (uniform pressure or exponential pressure), but only approximately calculates the diving time and the stay time as the working time, and directly substitutes into the mathematical model for calculation. It is only an approximate calculation, and the calculated nitrogen tension is larger. The person also has this problem in the ascending process. In order to solve this problem, the mathematical model for calculating the inert gas tension of the tissue is established based on the theory that the diffusion speed of the gas is proportional to the pressure difference, which is recognized in physics and medicine, and the theoretical inert gas tension of the tissue at any time during the linear pressure increase, linear pressure decrease and exponential pressure increase process can be accurately calculated. SUMMARY

[0017] The present application provides a method for constructing a model for calculating the inert gas tension in human tissue.

[0018] The present application solves the above technical problems by the following technical solutions:

[0019] The present application provides a method for constructing a model for calculating the inert gas tension in human tissue, characterized in that it comprises the following steps:

[0020] S1, establishing a pressure change rate function of a certain tissue of the human body based on the theory that the diffusion speed of the gas is proportional to the pressure difference;

[0021] S2, performing formal transformation on the pressure change rate function of the certain tissue of the human body to obtain a corresponding first-order non-homogeneous linear differential equation;

[0022] S3, constructing a standard form and a general solution form of the first-order non-homogeneous linear differential equation;

[0023] S4, corresponding assignment is made to the first-order non-homogeneous linear differential equation and its general solution form, and the general human body certain tissue pressure function is obtained;

[0024] S5, using the general human body certain tissue pressure function, the human body certain tissue pressure function g1(x) under the respiratory gas exponential pressurization scene, the human body certain tissue pressure function g2(x) under the respiratory gas linear decompression scene, and the human body certain tissue pressure function g3(x) under the respiratory gas linear pressurization scene are respectively constructed;

[0025] S6, using the human body certain tissue pressure function g1(x) and the percentage content of the inert gas, the human body certain tissue inert gas tension calculation model G1(x) under the respiratory gas exponential pressurization scene is constructed;

[0026] Using the human body certain tissue pressure function g2(x) and the percentage content of the inert gas, the human body certain tissue inert gas tension calculation model G2(x) under the respiratory gas linear decompression scene is constructed;

[0027] Using the human body certain tissue pressure function g3(x) and the percentage content of the inert gas, the human body certain tissue inert gas tension calculation model G3(x) under the respiratory gas linear pressurization scene is constructed.

[0028] The positive progress effect of the present application is that:

[0029] The present application is based on the theory that the diffusion speed of gas is proportional to the pressure difference, and establishes a mathematical model for calculating the inert gas tension of the tissue, which can accurately calculate the theoretical inert gas tension such as nitrogen tension of a certain tissue at any moment during the linear pressurization, linear decompression and exponential pressurization of the environmental pressure. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flow chart of the inert gas tension calculation model construction method for human tissue of the preferred embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0032] As shown in Figure 1 The inert gas tension calculation model construction method for human tissue provided by the embodiments of the present application includes the following steps:

[0033] Step 101, based on the theory that the diffusion speed of gas is proportional to the pressure difference, the pressure change rate function of a certain tissue of human body is established, denoted as formula (1):

[0034] g'(x) = k [f(x) - g(x)] (1)

[0035] In the formula, f(x) is the pressure of respiratory gas (environmental gas), unit: m; g(x) is the pressure of a certain tissue in the body, unit: m; g'(x) is the pressure change rate of a certain tissue in the body, unit: m / s; k is defined as a saturation coefficient, dimensionless, and k is defined to be greater than 0, when f(x) is greater than g(x), g'(x) is greater than 0, when f(x) is less than g(x), g'(x) is less than 0, and k = ln2 / t is calculated, t is the half-saturation time of a certain tissue in the body, unit: s.

[0036] Step 102, the form of the pressure change rate function of a certain tissue of human body formula (1) is transformed to obtain a corresponding first-order non-homogeneous linear differential equation denoted as formula (2):

[0037] g'(x) + k·g(x) = k·f(x) (2)

[0038] Step 103, the standard form of the first-order non-homogeneous linear differential equation formula (2) is constructed, denoted as formula (3) and its general solution form is denoted as formula (4):

[0039]

[0040] Step 104, the first-order non-homogeneous linear differential equation formula (2) and its general solution form formula (4) are assigned values, then P(x) = k, Q(x) = kf(x), and formula (4) is substituted to obtain a general human tissue pressure function denoted as formula (5):

[0041] g(x) = e -kx (∫kf(x)e kx dx+C) (5)

[0042] In the formula, C is an arbitrary constant, which needs to be determined by the initial condition.

[0043] Step 105, using the general human tissue pressure function formula (5), a certain tissue pressure function g1(x) of human body under the scene of exponential increase of respiratory gas, a certain tissue pressure function g2(x) of human body under the scene of linear decrease of respiratory gas, and a certain tissue pressure function g3(x) of human body under the scene of linear increase of respiratory gas are constructed respectively.

[0044] 1) Exponential increase of respiratory gas (environmental gas) pressure

[0045] Use scene: the diver is in the pressurized cabin, and the cabin pressure is controlled to increase exponentially.

[0046] Taking exponential compression function, pressure doubles every n seconds, set Where P0 is the initial pressure of breathing gas.

[0047] Substitute into equation (5), get

[0048] The value of g(0) is generally known, x=0s into equation (6) get

[0049]

[0050]

[0051] Substitute C into equation (6), build the pressure function g1(x) of human tissue in the exponential compression scenario of breathing gas:

[0052]

[0053] If the pressure of human tissue has been fully balanced with the ambient pressure at the beginning of compression, then g(0)=P0; If the test personnel exist repeated diving / pressure increase and decrease at the beginning of compression, the value of g(0) should be fully considered in actual situation.

[0054] When g(0)=P0 is substituted into equation (7), get

[0055]

[0056] Substitute equation (9) into equation (6), get

[0057]

[0058] 2) Breathing gas (ambient gas) linear decompression

[0059] Use scenario A: divers from a large depth to a certain shallow depth at a constant speed;

[0060] Use scenario B: divers in the compression chamber, control the cabin pressure to reduce at a constant speed.

[0061] The mathematical model corresponding to the linear decompression of breathing gas is f(x)=P1-ax, where P1 is the initial pressure of breathing gas, a is a constant, a represents the ambient pressure decreases a meters per second.

[0062] Substitute f(x)=P1-ax into equation (5), get

[0063]

[0064] The value of g(0) is generally known, x=0s into equation (11) get

[0065] ​

[0066] At this point, g(0) is the tissue pressure value before decompression. Substituting equation (12) into equation (11), we construct the tissue pressure function g2(x) of the human body under the linear decompression scenario of respiratory gas:

[0067]

[0068] 3) Linear pressurization of respiratory gases (ambient gases)

[0069] Use case A: A diver descends from a shallow depth to a certain greater depth at a constant speed;

[0070] Use Case B: A diver is in a pressurized chamber, and the chamber pressure is being increased at a constant rate.

[0071] The mathematical model corresponding to the linear pressurization of the breathing gas is f(x) = P0 + bx, where P0 is the initial pressure of the breathing gas, b represents a constant, and b represents the increase of the ambient pressure by b meters per second.

[0072] Substituting f(x) = P0 + bx into equation (5), we get

[0073]

[0074] The value of g(0) is generally known. Substituting x = 0s into equation (14) yields...

[0075]

[0076] Substituting equation (15) into equation (14) yields

[0077]

[0078] If the pressure of human tissue is already fully balanced with the environmental pressure at the start of pressurization, then g(0) = P0. If, at the start of pressurization, the test personnel are subject to repeated diving / decompression, the value of g(0) should fully consider the actual situation.

[0079] When g(0) = P0, at this time

[0080] Step 106: Construct a calculation model for the tension of an inert gas in a human tissue under the exponential pressurization scenario of respiratory gases, using the pressure function g1(x) of a certain human tissue and the percentage content d of the inert gas. The model is G1(x) = d * g1(x).

[0081] A calculation model for the tension of an inert gas in a human tissue under a linear decompression scenario is constructed using the pressure function g2(x) of a certain human tissue and the percentage content d of the inert gas. The model is G2(x) = d * g2(x).

[0082] A human tissue pressure function g3(x) and the percentage content d of the inert gas are used to construct a human tissue inert gas tension calculation model G3(x)=d*g3(x) under the linear pressurization of respiratory gas.

[0083] When calculating the nitrogen tension of human tissue, d is 0.79.

[0084] The present application is based on the theory that the diffusion speed of gas is proportional to the pressure difference to establish a mathematical model for calculating the inert gas tension of tissue, which can accurately calculate the theoretical inert gas tension such as nitrogen tension of certain tissue at any time during the linear pressurization, linear depressurization and exponential pressurization of environmental pressure.

[0085] The final mathematical model is shown in Table 1. When calculating the nitrogen tension of tissue, only 0.79 needs to be multiplied.

[0086] Table 1 Mathematical model

[0087]

[0088] Although the specific embodiments of the present application are described above, those skilled in the art should understand that these are only illustrative, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A method for constructing a model for calculating tension of an inert gas in human tissue, characterized by, It comprises the following steps: S1, based on the theory that the diffusion speed of gas is proportional to the pressure difference, a human body certain tissue pressure change rate function is established; S2, the human body certain tissue pressure change rate function is transformed in form to obtain a corresponding first-order non-homogeneous linear differential equation; S3, a standard form of the first-order non-homogeneous linear differential equation and a general solution form thereof are constructed; S4, the first-order non-homogeneous linear differential equation and the general solution form thereof are correspondingly valued and substituted into the general solution form to obtain a general human body certain tissue pressure function; S5, the general human body certain tissue pressure function is used to construct a human body certain tissue pressure function g1(x) under a respiratory gas exponential pressurization scenario, a human body certain tissue pressure function g2(x) under a respiratory gas linear depressurization scenario, and a human body certain tissue pressure function g3(x) under a respiratory gas linear pressurization scenario; S6, the human body certain tissue pressure function g1(x) and the percentage content of the inert gas are used to construct a human body certain tissue inert gas tension calculation model G1(x) under the respiratory gas exponential pressurization scenario; The human body certain tissue pressure function g2(x) and the percentage content of the inert gas are used to construct a human body certain tissue inert gas tension calculation model G2(x) under the respiratory gas linear depressurization scenario; The human body certain tissue pressure function g3(x) and the percentage content of the inert gas are used to construct a human body certain tissue inert gas tension calculation model G3(x) under the respiratory gas linear pressurization scenario.

2. The method for constructing a calculation model for inert gas tension in human tissue as described in claim 1, characterized in that, S1, based on the theory that the diffusion speed of gas is proportional to the pressure difference, a human body certain tissue pressure change rate function is established and denoted as formula (1): g'(x)=k[f(x)-g(x)] (1) In the formula, f(x) is the respiratory gas, i.e., the environmental gas pressure, with a unit of m; g(x) is the pressure of a certain tissue in the body, with a unit of m; g'(x) is the pressure change rate of a certain tissue in the body, with a unit of m / s; k is defined as a saturation coefficient, which is dimensionless, and k is defined to be greater than 0; when f(x) is greater than g(x), g'(x) is greater than 0; when f(x) is less than g(x), g'(x) is less than 0; it is calculated that k=ln2 / t, t is the half-saturation time of a certain tissue in the body, with a unit of s; S2, the human body certain tissue pressure change rate function is transformed in form to obtain a corresponding first-order non-homogeneous linear differential equation denoted as formula (2): g'(x)+k·g(x)=k·f(x) (2) S3, a standard form of the first-order non-homogeneous linear differential equation is constructed and denoted as formula (3), and a general solution form thereof is denoted as formula (4): S4, formula (4) and formula (2) are correspondingly valued, then P(x)=k and Q(x)=kf(x) are substituted into formula (4) to obtain a general human body certain tissue pressure function denoted as formula (5): g(x) = e -kx (∫kf(x)e kx dx + C) (5) In the formula, C is an arbitrary constant, which needs to be determined through an initial condition; In S5, the exponential pressure function is taken, the pressure is doubled every n seconds, and let where P0 is the initial pressure of the breathing gas, and Substituting equation (5) into equation (4), we get The value of g(0) is generally known, x=0s is substituted into formula (6) to obtain C is substituted into formula (6) to construct a human body certain tissue pressure function g1(x) under a respiratory gas exponential pressurization scenario: If the human tissue pressure has been fully balanced with the ambient pressure at the beginning of the pressurization, g(0) = P0, if the test personnel exist repeated diving / pressure increase / decrease at the beginning of the pressurization, the value of g(0) should be fully considered in the actual situation; In S6, a calculation model G1(x) = d*g1(x) of the inert gas tension of the human tissue in the breathing gas pressurization scenario is constructed.

3. The method for constructing a calculation model for inert gas tension in human tissue as described in claim 2, characterized in that, In S5, the mathematical model of the linear decompression of the breathing gas is f(x) = P1-ax, where P1 is the initial pressure of the breathing gas, f(x) = P1-ax is substituted into formula (5), and The value of g(0) is generally known, x = 0s is substituted into formula (11), and At this time, g(0) is the tissue pressure value before decompression, formula (12) is substituted into formula (11), and the pressure function g2(x) of the human tissue in the linear decompression scenario of the breathing gas is constructed: In S6, a calculation model G2(x) = d*g2(x) of the inert gas tension of the human tissue in the linear decompression scenario of the breathing gas is constructed.

4. The method of claim 3, wherein the inert gas tension in human tissue is calculated by the following equation: ###0001### wherein, P is the inert gas tension in human tissue, P0 is the inert gas tension in the air, and H is the height of the human body. The linear decompression scenario of the breathing gas includes: Use scenario A: the diver uniformly ascends from a great depth to a certain shallow depth; Use scenario B: the diver is in a pressurized cabin, and the cabin pressure is uniformly reduced.

5. The method of claim 2, wherein the inert gas tension calculation model of human tissue is constructed by using the following equation: ###0002### where, P is the inert gas tension, C is the constant, and T is the temperature. In S5, the mathematical model of the linear pressurization of the breathing gas is f(x) = P0+bx, where P0 is the initial pressure of the breathing gas, f(x) = P0+bx is substituted into formula (5), and The value of g(0) is generally known, x = 0s is substituted into formula (14), and Formula (15) is substituted into formula (14), and If the human tissue pressure has been fully balanced with the ambient pressure at the beginning of the pressurization, g(0) = P0, if the test personnel exist repeated diving / pressure increase / decrease at the beginning of the pressurization, the value of g(0) should be fully considered in the actual situation; In S6, a calculation model G3(x) = d*g3(x) of the inert gas tension of the human tissue in the linear pressurization scenario of the breathing gas is constructed.

6. The method for constructing a calculation model for inert gas tension in human tissue as described in claim 5, characterized in that, The linear pressurization scenario of the breathing gas includes: Use scenario A: the diver uniformly descends from a shallow depth to a certain great depth; use scenario B: the diver is in a pressurized cabin, and the cabin pressure is uniformly increased.

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