RER estimation method, device and equipment based on PetCO2 and storage medium

Abstract

The embodiment of the invention provides a PetCO2-based RER estimation method, device and equipment and a storage medium, firstly, an upper computer sends a connection signal to measurement equipment for connection when a user state is an initial state, and then displays a user real-time expiration flow and a user Ef when the user state is converted from a quasi expiration state to a constant flow expiration state; the difference value between the real-time expiratory flow of the user and the user Ef is within a preset threshold range, then a measurement stopping instruction is sent to the measuring device when the preset time is up and the user state is an exhalation state, and the end-expiratory carbon dioxide concentration is calculated according to the real-time expiratory flow; and finally, obtaining a corresponding RER value according to the mapping relationship between the end-expiratory carbon dioxide concentration and the RER. The RER value is estimated through the end-expiratory carbon dioxide concentration, so that the measurement process is simplified, and the manufacturing cost and the maintenance cost of equipment can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of respiratory metabolism detection, and in particular to a method, device, equipment and storage medium for estimating RER based on PetCO2. Background Art

[0002] Respiratory metabolism testing is one of the important means to evaluate the energy source and consumption of the human body. Since the Douglas bag method was first proposed, it has a history of nearly 100 years. During this period, with the advancement of science and technology, a variety of measurement schemes such as the step-by-step breathing method and the mixed gas chamber method have gradually developed. The basis of these methods is four basic biomedical principles: 1. In a resting state, except for carbohydrate aerobic metabolism and fat metabolism, the amount of oxygen consumed and the amount of carbon dioxide produced by other chemical reactions can be ignored. 2. According to the chemical equation of carbohydrate aerobic metabolism, the ratio of carbon dioxide generated to oxygen consumed is 1:1. 3. The ratio of carbon dioxide generated to oxygen consumed in fat metabolism is approximately 0.7:1. 4. By measuring the oxygen content, carbon dioxide content and the total volume of inhaled and exhaled gas during a person's inhalation and exhalation at rest, the ratio of carbon dioxide production to oxygen consumption can be calculated, thereby inferring which energy source the individual mainly relies on for energy supply. At present, most of the metabolic vehicles commonly used in hospital nutrition departments use the mixed gas chamber method to determine the respiratory exchange ratio (RER) of the subject.

[0003] The Douglas bag method is the earliest technology used for indirect calorimetry and is considered the "gold standard" in this field. Its working principle is to collect all the gas expelled by the test subject during exercise in one or more pre-prepared air bags, and then analyze the total volume and composition of the gas in the air bag to estimate the energy consumption during the entire activity cycle.

[0004] In order to overcome the problem that the Douglas bag method cannot monitor in real time and can only provide average data, the step-by-step breathing method came into being with the development of computer technology and sensor technology. This method allows the specific parameters of each breath of an individual to be monitored at all times, such as flow rate, O2 / CO2 concentration, etc., and then instantly feedback the trend of metabolic rate changes in the current state.

[0005] The mixed gas chamber method is to fully mix all the gases exhaled by the subject in a space of about 5 liters, and then uniformly measure the proportion of each component. Compared with the Douglas bag method, although it is not as capable of achieving complete real-time monitoring as the step-by-step breathing method, it can also achieve the effect of more accurately reflecting the average RER in a short period of time; compared with the step-by-step breathing method, although the response speed is slightly inferior, its system design is more robust, the signal processing is relatively simple, and the requirements for sensor performance are reduced.

[0006] The advantage of the mixed air chamber method is that it can calculate the average RER value within a specific time period more accurately; for developers, this solution is easy to implement and has low hardware costs. It only needs to ensure that the test subject is in a state close to the resting heart rate and continuously measure for about 15 minutes to obtain reliable results; the price range of mainstream models on the market is roughly between RMB 300,000 and 600,000. However, its disadvantage is that for end users, the operation is complex and the conditions are harsh - not only professional knowledge is required to correctly install and calibrate the relevant instruments, but the entire measurement process is also very lengthy and difficult to meet the needs of frequent daily use; the high cost makes it difficult for ordinary consumers to afford it, and the large size of the equipment makes it inconvenient to carry out.

[0007] Therefore, although the existing respiratory metabolic detection equipment based on the mixed gas chamber method can meet the needs of the professional field to a certain extent, there are still many obstacles in its promotion to the mass market. Therefore, it is particularly necessary to develop a solution. Summary of the invention

[0008] The present application provides a PetCO2-based RER estimation method, device, equipment and storage medium. Estimating the RER value by end-tidal carbon dioxide concentration not only simplifies the measurement process, but also reduces the cost of equipment construction and maintenance costs.

[0009] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0010] In a first aspect, an embodiment of the present application provides a method for estimating RER based on PetCO2, the method being applied to a host computer connected to a measuring device, the method comprising:

[0011] When the user state is in the initial state, a connection signal is sent to the measuring device to connect;

[0012] When the user state changes from the quasi-expiratory state to the constant-flow exhalation state, the user's real-time exhalation flow and the user's Ef are displayed, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range;

[0013] When the preset time is reached and the user is in the exhalation state, a stop measurement instruction is sent to the measuring device, and the end-tidal carbon dioxide concentration is calculated based on the real-time exhalation flow;

[0014] The corresponding RER value is obtained according to the mapping relationship between end-tidal carbon dioxide concentration and RER.

[0015] In a possible implementation, the mapping relationship between end-tidal carbon dioxide concentration and RER is obtained through user personal information, and the user personal information includes expiratory flow in a constant flow expiratory state, vital capacity in a constant flow expiratory state, height, weight, gender, age, race, work and rest habits, time zone, measurement time and a mapping relationship table.

[0016] In one possible implementation, the measuring device includes a carbon dioxide sensor and a flow sensor;

[0017] The absolute error of the carbon dioxide concentration measurement value of the carbon dioxide sensor is 0.5%, the sampling frequency is greater than 5hz, and the response time is less than 500ms.

[0018] The relative error of the flow measurement value of the flow sensor is 15%, the sampling frequency is greater than 5hz, and the response time is less than 500ms.

[0019] In a possible implementation manner, the end-tidal carbon dioxide concentration and the RER are in a one-to-one mapping relationship.

[0020] In a second aspect, the present application also proposes a device for estimating RER based on PetCO2, the device comprising:

[0021] A sending module, used for sending a connection signal to the measuring device for connection when the user state is an initial state;

[0022] A measurement module, used for displaying the user's real-time exhalation flow and the user's Ef when the user's state is converted from the quasi-exhalation state to the constant-flow exhalation state, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range;

[0023] A calculation module, used to send a stop measurement instruction to the measuring device when a preset time is reached and the user is in the exhalation state, and calculate the end-tidal carbon dioxide concentration according to the real-time exhalation flow;

[0024] The generation module is used to obtain the corresponding RER value according to the mapping relationship between the end-tidal carbon dioxide concentration and the RER.

[0025] In a third aspect, the present application further proposes a computer device, comprising a processor and a memory, wherein the memory stores a computer program, and the computer program is loaded and executed by the processor to implement the RER estimation method as described in any one of the first aspects.

[0026] In a fourth aspect, the present application further proposes a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is loaded and executed by a processor to implement the RER estimation method as described in any one of the first aspects.

[0027] The above-mentioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application; and in the present application, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0028] Compared with the prior art, the embodiments of the present application provide a method, device, equipment and storage medium for estimating RER based on PetCO2. First, when the user state is in the initial state, the host computer sends a connection signal to the measuring device for connection. Secondly, when the user state is converted from the quasi-expiratory state to the constant flow expiratory state, the user's real-time expiratory flow and the user's Ef are displayed, so that the difference between the user's real-time expiratory flow and the user's Ef is within the preset threshold range. Then, when the preset time is reached and the user state is in the exhalation state, a stop measurement instruction is sent to the measuring device, and the end-tidal carbon dioxide concentration is calculated according to the real-time expiratory flow. Finally, the corresponding RER value is obtained according to the mapping relationship between the end-tidal carbon dioxide concentration and RER. Estimating the RER value by the end-tidal carbon dioxide concentration not only simplifies the measurement process, but also reduces the cost and maintenance cost of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A schematic flow chart of the RER estimation method based on PetCO2 proposed in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0033] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0034] In the prior art, the disadvantages of the mixed gas chamber method are: first, the measurement operation is too cumbersome for the user - a single measurement cannot be completed by a single user, and a single measurement takes too long. Second, the accuracy requirements for the sensor are relatively high, and the equipment is large in size, resulting in high cost and maintenance costs.

[0035] Therefore, in order to reduce the cost of the measuring equipment and simplify the user's operation, the embodiment of the present application proposes a RER estimation method, device, equipment and storage medium based on PetCO2. By requiring the user to take a deep breath, hold the breath for 10 seconds, and then blow out the gas in the body at a constant flow rate toward a measuring instrument, the timing signal data of the carbon dioxide sensor in the measuring instrument is used to calculate the corresponding RER, which can greatly reduce the cost of the equipment and maintenance costs. In addition, the user's single measurement time is shortened to less than 30 seconds, and the measurement process is as simple as possible, so that any toC end user can use this device quickly to get started, which is described in detail below.

[0036] The user's measurement phase includes and only includes 4 states, which are: initial state, quasi-expiratory state, constant flow exhalation state, and exhalation state:

[0037] Initial state (_INIT_): The human body is at rest and inhales until the lungs are just filled with gas. At this time, the concentrations of oxygen, nitrogen and carbon dioxide in the lungs are equal to the concentrations of the corresponding components in the atmosphere.

[0038] Ready state: the state reached after holding the breath for 10 seconds from the initial state. This means that at this point, the human body is ready to start exhaling at a constant speed.

[0039] Constant flow exhalation state (_EXHALE_): Starting from the quasi-expiratory state (_READY_), the individual begins to exhale at a constant rate. The "constant flow" here refers to the exhalation speed that remains unchanged throughout the exhalation process, which is determined by the vital capacity divided by the total exhalation time.

[0040] End of exhalation (_END_): The state reached when an individual continues to exhale at a constant flow rate until exhalation stops naturally due to insufficient air available in the lungs. This marks the end of a complete breathing cycle.

[0041] Define variable symbols. Ef: Expiratory flow in EXHALE. Vc: Vital capacity in EXHALE. T: Expiratory time in EXHALE. PetCO2: End-tidal carbon dioxide concentration, i.e., the carbon dioxide concentration of exhaled gas in the human body at END. PvCO2: Pulmonary venous carbon dioxide concentration, which is equal to the partial pressure of carbon dioxide dissolved in the pulmonary venous blood (in mmhg) divided by the atmospheric pressure (equal to 780 mnhg). V_total: Total gas volume in the body (in ml). V_total[_INIT_]: Total gas volume in the body at INIT. V_total[_READY_]: Total gas volume in the body at READY. V_total[_EXHALE_]: Total gas volume in the body at EXHALE. V_total[_END_]: Total gas volume in the body at END. V_O2: Oxygen content in the body (in ml). V_O2[_INIT_]: The oxygen content in the human body at _INIT_. V_O2[_READY_]: The oxygen content in the human body at _READY_.

[0042] V_CO2: The amount of carbon dioxide in the human body (unit: ml). V_CO2[_INIT_]: The amount of carbon dioxide in the human body under _INIT_. V_CO2[_READY_]: The amount of carbon dioxide in the human body under _READY_. V_CO2[_EXHALE_]: The amount of carbon dioxide in the human body under _EXHALE_ (a quantity related to the exhalation time t). V_CO2[_END_]: The amount of carbon dioxide in the human body under _END_. V_CO2(_EXHALE_): The amount of carbon dioxide exhaled by the human body under _EXHALE_ (unit: ml). V_O2(_EXHALE_): The amount of oxygen exhaled by the human body under _EXHALE_ (unit: ml). V_CO2(raise): The amount of carbon dioxide generated by the human body in a certain period of time (here specifically refers to the amount of carbon dioxide generated by the user during the process from _INIT_ to _READY_). That is, V_CO2(raise)=V_CO2[_READY_]-V_CO2[_INIT_]. V_O2(comsume): The oxygen consumption of the human body in a certain period of time (here specifically refers to the oxygen consumption of the user from _INIT_ to _READY_). That is, V_O2(comsume)=V_O2[_INIT_]-V_O2[_READY_]. RER: The respiratory quotient of the human body at rest. RER=V_CO2(raise) / V_O2(comsume). Under normal circumstances, RER∈[0.7,1].

[0043] Based on the above, it is assumed that for people of the same height, weight, gender, age, race, and work and rest habits, in the same time zone and in the same time period, the oxygen consumption rate from _INIT_ to _READY_ is the same. The calculation formula for oxygen consumption rate is oxygen consumption rate = V_O2(comsume) / V_total[_INIT_].

[0044] In any case, if the user prolongs the breath-holding time in READY, the value of VCO2[READY] / Vtotal[READY] will not change. In addition, the user's T in EXHALE is 8s. (VCO2 / Vtotal ) = PetCO2.

[0045] During the user's _EXHALE_ period, the value of (V_CO2[_EXHALE_] / V_total[_EXHALE_]) remains unchanged, and PetCO2 = PvCO2. When the human body is at rest, only the aerobic metabolism of carbohydrates and lipid metabolism involve oxygen consumption and carbon dioxide production.

[0046] In the atmosphere, only the concentrations of nitrogen, oxygen, carbon dioxide, and rare gases are considered, among which the concentration of nitrogen = 78%, the concentration of oxygen = 20%, the concentration of rare gases = 2%, and the concentration of carbon dioxide = 0%. V_total[_INIT_] = V_total[_READ_] (it has been demonstrated that V_total[_READ_] will vary with the source of energy supply to the human body, but the difference is less than V_total[_INIT_]*2% and can be ignored). PvCO2 is an indicator that can truly reflect the amount of carbon dioxide generated in the metabolism of the human body at the cellular level - V_CO2[_READY_] = PvCO2*V_total[_READ_].

[0047] It is worth noting that when a person is at rest, except for the aerobic metabolism of carbohydrates and lipid metabolism, the amount of oxygen consumed and the amount of carbon dioxide produced by the other chemical reactions are constant, or the content is very low and can be ignored. According to the chemical reaction formula of the aerobic metabolism of carbohydrates in the human body, the ratio of the carbon dioxide content generated to the oxygen content consumed is = 1:1. According to the chemical reaction formula of the lipid metabolism in the human body, the ratio of the carbon dioxide content generated to the oxygen content consumed is = 0.7:1 (approximate value). The proportion of a person's energy supply from carbohydrates is (RER–0.7) / (1-0.7), and the proportion from fat is (1-RER) / (1-0.7).

[0048] The embodiment of the present application proposes a RER estimation method based on PetCO2, which is applied to a host computer connected to a measuring device, wherein a product manufactured by using the method is divided into a hardware part and a software part.

[0049] In the hardware part, the flow sensor is used to measure the air flow through the airway, the carbon dioxide sensor detects the concentration of carbon dioxide in the gas, and the Bluetooth module allows the measuring device to communicate wirelessly with the host computer or other smart devices to transmit the collected data. The airway provides a channel for the user to breathe normally while the sensor can accurately capture information during the breathing process. The power supply powers the entire measuring electronic device to ensure that all components can operate normally. The indicator light is used to display the working status of the device, the battery level, or to remind the user when to start / stop the test. The above components are assembled in a device similar to the size of an e-cigarette, which is easy to carry and easy to use. All electronic components are integrated on a circuit board to form a compact and fully functional portable measurement tool.

[0050] The host computer is also in the hardware part, where Bluetooth receives data from the measuring electronic equipment. The data processing module is responsible for processing the received data, including but not limited to steps such as cleaning and format conversion for subsequent analysis. The display screen: displays the processed information, such as real-time RER values, historical records and other visual content for users to view.

[0051] In the software part, the data mapping table defines how to convert the raw sensor readings into meaningful information, such as how to deduce the specific RER value from the flow and CO2 concentration data. The user information management stores the personal information of each user, including but not limited to basic information such as Vc (vital capacity), Ef (efficiency factor), height, weight, gender, age, race, as well as dynamic information such as work and rest habits, time zone, specific measurement time, etc. The RER calculation interface uses an algorithm to calculate the personalized RER value based on all the relevant information collected above. This process involves complex mathematical models to ensure that the results reflect the user's actual metabolic condition as accurately as possible.

[0052] Please refer to Figure 1 , Figure 1 The flowchart of the RER estimation method based on PetCO2 proposed in the embodiment of the present application is shown, and the method comprises:

[0053] Step S1: When the user state is in the initial state, a connection signal is sent to the measuring device to connect.

[0054] In step S1, the user first logs in to the account on the host computer. After successful login, the host computer will automatically load the user's personal information and related data. The user's personal information includes the expiratory flow in the constant flow exhalation state, the vital capacity in the constant flow exhalation state, height, weight, gender, age, race, work and rest habits, time zone, measurement time and mapping relationship table. After that, in order to prepare to receive data from the measuring electronic device, the user needs to manually turn on the Bluetooth function of the host computer to ensure that wireless communication can be established between the two devices, and the user turns on the power of the measuring electronic device. At this time, the indicator light on the device will turn green, indicating that the device is powered on and in standby mode.

[0055] The measuring electronic device will automatically search and try to connect to the host computer with Bluetooth turned on. Once the two are successfully paired and connected, the indicator light on the measuring electronic device will turn blue, indicating that the Bluetooth connection has been established, and then the user takes a deep breath to reach a relatively stable baseline state (_INIT_). This state is to ensure that the user is in a resting state during measurement in order to obtain accurate breathing data. In this initial state, the user presses the "Start Measurement" button on the measuring electronic device. This operation not only starts the data collection process, but also sends a connection signal to the measuring electronic device to confirm that the host computer is ready to receive data. After pressing the "Start Measurement" button, the measuring electronic device collects data through its built-in flow sensor and carbon dioxide sensor, and sends it to the host computer for processing in real time via Bluetooth. At the same time, the indicator light of the measuring electronic device changes to yellow, indicating that the data collection task is being performed.

[0056] Step S2: When the user state is converted from the quasi-expiratory state to the constant-flow exhalation state, the user's real-time exhalation flow and the user's Ef are displayed, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range.

[0057] In step S2, a 10-second countdown is displayed on the host computer interface. The user holds his breath according to the prompt of the host computer to reach a state close to _READ_. The user needs to take a deep breath and keep holding his breath until the countdown ends. When the 10-second breath-holding countdown ends, the host computer interface will display a prompt of "start exhaling". The user starts exhaling according to the prompt of the host computer and enters the _EXHALE_ state. The measuring electronic device transmits the user's exhalation flow signal to the host computer in real time via Bluetooth. At this time, the host computer will detect a flow value significantly greater than 0.

[0058] The host computer interface will display the user's current real-time exhalation flow rate. At the same time, the host computer will also display the user's Ef value (Ef = Vc / T, where Vc is vital capacity and T is exhalation time). After that, an 8-second countdown will be displayed on the interface to help the user adjust the exhalation strength. The user adjusts his or her exhalation strength according to the difference between the real-time exhalation flow rate displayed by the host computer and his or her own Ef value, so as to make it as close to the Ef value as possible, and ensure that the difference between the two is within the preset threshold range.

[0059] Step S3: When the preset time is reached and the user is in the exhalation state, a stop measurement instruction is sent to the measuring device, and the end-tidal carbon dioxide concentration is calculated according to the real-time exhalation flow.

[0060] After the 8-second countdown displayed on the host computer interface ends, the interface will display a prompt "Measurement Completed", and the host computer will send a "Stop Measurement" command to the measuring electronic device. At this time, the user reaches the _END_ state, that is, the call-out state. After receiving the "Stop Measurement" command, the measuring electronic device will disconnect the Bluetooth connection with the host computer and change the indicator light from yellow to green, indicating that the device has stopped working and returned to the standby state.

[0061] The product's software processes the real-time signal data collected by the flow sensor and the carbon dioxide sensor during the measurement process. By analyzing this data, the software can calculate the end-tidal carbon dioxide concentration (PetCO2). Specifically, PetCO2 is the carbon dioxide concentration in the last part of the gas during exhalation, which is usually used to evaluate lung ventilation function and metabolic status.

[0062] Step S4: obtaining a corresponding RER value according to the mapping relationship between the end-tidal carbon dioxide concentration and the RER.

[0063] The mapping relationship between end-tidal carbon dioxide concentration and RER is obtained through user personal information, which includes expiratory flow in constant flow expiratory state, vital capacity in constant flow expiratory state, height, weight, gender, age, race, work and rest habits, time zone, measurement time and mapping relationship table.

[0064] The product software generates a mapping relationship between PetCO2 and RER based on user information and a mapping relationship table, which contains the corresponding relationships between different PetCO2 values ​​and RER values. These relationships are based on a large amount of data and scientific research. The software generates a mapping relationship between PetCO2 and RER specific to the user based on the above user information and mapping relationship table. This mapping relationship takes into account individual differences among users, making the calculation results more accurate.

[0065] Through the data collected in real time by the flow sensor and carbon dioxide sensor, the software has calculated the user's actual PetCO2 value. The software will compare the actually measured PetCO2 value with the previously generated mapping relationship between PetCO2 and RER to find the closest PetCO2 value and its corresponding RER value. Finally, the software will output the corresponding RER value to evaluate the user's metabolic state and energy consumption.

[0066] In one possible implementation, the measuring device includes a carbon dioxide sensor and a flow sensor;

[0067] The absolute error of the carbon dioxide concentration measurement value of the carbon dioxide sensor is 0.5%, the sampling frequency is greater than 5hz, and the response time is less than 500ms.

[0068] The relative error of the flow measurement value of the flow sensor is 15%, the sampling frequency is greater than 5hz, and the response time is less than 500ms.

[0069] The functions of the flow sensor are: First, inform the host computer of the user's exhalation status: by detecting the flow change, the flow sensor can determine whether the user has started to exhale or stopped exhaling. Second, display the difference between the user's flow value and Ef in real time: help the user exhale at a constant flow rate and ensure that a specific end point (_END_) is reached at 8 seconds.

[0070] The accuracy requirement is that the relative error is less than 15%. In the flow range of 15L / min to 55L / min, the maximum relative deviation between the sensor's measured value and the true value does not exceed 15%. For example, if the actual flow is 30L / min, the measured value should be between 25.5L / min and 34.5L / min. The sampling frequency is greater than 5Hz, and at least 5 data points are collected per second to ensure the continuity and accuracy of the data. The response time is less than 500ms. The time from the sensor detecting the flow change to outputting a stable reading does not exceed 500 milliseconds, ensuring real-time performance and fast response.

[0071] The function of the carbon dioxide sensor is to calculate PetCO2 (end-tidal carbon dioxide), establish a one-to-one mapping relationship with the data set, and thus calculate the RER (respiratory exchange rate). The value range of PetCO2 is that a normal person consumes about 6% of oxygen during the period from INIT to READY. This will cause the body to produce carbon dioxide with a concentration of 4.2% to 6% (the carbon dioxide concentration produced when fat is completely metabolized is 4.2%, and the carbon dioxide concentration produced when carbohydrates are completely metabolized is 6%).

[0072] Carbon dioxide sensor accuracy requirements: absolute error 0.5%. In the CO2 concentration range of 4.2% to 6%, the maximum deviation between the sensor's measured value and the true value does not exceed 0.5%. For example, if the actual CO2 concentration is 5%, the measured value should be between 4.975% and 5.025%. The sampling frequency is greater than 5Hz, and at least 5 data points are collected per second to ensure data continuity and accuracy. The response time is less than 500ms. The time from the sensor detecting a change in CO2 concentration to outputting a stable reading does not exceed 500 milliseconds, ensuring real-time performance and fast response.

[0073] In a possible implementation manner, the end-tidal carbon dioxide concentration and the RER are in a one-to-one mapping relationship.

[0074] Under the above defined assumptions and user measurement steps, the definition formula RER = V_CO2(raise) / V_O2(comsume) is equivalent to RER = PetCO2 / oxygen consumption rate. According to the definition of RER: RER = V_CO2(raise) / V_O2(comsume). The oxygen consumption rate of this person is obtained based on the user's physical information. Therefore, the calculation formula of RER can be written as RER = V_CO2(raise) / (V_total[_INIT_]*oxygen consumption rate). According to the definition of _INIT_, V_CO2[_INIT_] = 0. V_CO2(raise) = V_CO2[_READY_]-V_CO2[_INIT_]. V_CO2(raise) = V_CO2[_READY_]. PvCO2 can be used to measure the actual situation of carbon dioxide concentration in the human body. RER = (V_total[_INIT_]*PvCO2) / (V_total[_INIT_]*oxygen consumption rate). RER = PvCO2 / oxygen consumption rate. According to PetCO2 = PvCO2, RER = PetCO2 / oxygen consumption rate.

[0075] In summary, there is a one-to-one mapping relationship between PetCO2 and RER, which shows that under certain assumptions, RER can be directly calculated by measuring PetCO2 and known oxygen consumption rate.

[0076] In one possible embodiment, assuming that the carbon dioxide concentration in the atmosphere is 0%, in the (_INIT_) state, the carbon dioxide concentration in the human body is also defined as 0%. Therefore, in the (_READY_) state, the carbon dioxide concentration at the human body cell level is equal to the concentration of carbon dioxide produced in the body.

[0077] When the human body is in the (_READY_) state, the partial pressure of carbon dioxide in the alveoli (PvCO2) is equal to the concentration of carbon dioxide produced in the body. At this time, the value range of PetCO2 (end-tidal carbon dioxide concentration) is 4.2% to 6%, provided that the user's oxygen consumption rate is normal. Even if the oxygen consumption rate fluctuates slightly, this range will not change significantly.

[0078] This product requires that the absolute error of RER is less than 0.06. According to the previous derivation, RER is proportional to PetCO2. Therefore, in order to meet the error requirement of RER, the absolute error of PetCO2 needs to be controlled within 0.36% (the corresponding range is 2% to 10%). The filtering processing of carbon dioxide time series data by the host computer can reduce the absolute error of the sensor by 0.2%. Taking all factors into consideration, the absolute measurement error of the carbon dioxide sensor itself only needs to be less than 0.5% (corresponding to the carbon dioxide concentration measurement range of 2% to 10%).

[0079] The following is an embodiment of the present application and also proposes a RER estimation device based on PetCO2, which is used to execute each execution step and corresponding technical effect of the RER estimation method shown in the above embodiment and possible implementation method. The device includes:

[0080] A sending module, used for sending a connection signal to the measuring device for connection when the user state is an initial state;

[0081] A measurement module, used for displaying the user's real-time exhalation flow and the user's Ef when the user's state is converted from the quasi-exhalation state to the constant-flow exhalation state, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range;

[0082] A calculation module, used to send a stop measurement instruction to the measuring device when a preset time is reached and the user is in the exhalation state, and calculate the end-tidal carbon dioxide concentration according to the real-time exhalation flow;

[0083] The generation module is used to obtain the corresponding RER value according to the mapping relationship between the end-tidal carbon dioxide concentration and the RER.

[0084] This preferred embodiment provides a computer device, which can implement the steps in any embodiment of the RER estimation method provided in the embodiments of the present application. Therefore, the beneficial effects of the RER estimation method provided in the embodiments of the present application can be achieved. Please refer to the previous embodiments for details, which will not be repeated here.

[0085] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions, or by controlling related hardware through instructions, and the instructions can be stored in a computer-readable storage medium and loaded and executed by a processor. To this end, an embodiment of the present application provides a storage medium, which stores multiple instructions, and the instructions can be loaded by a processor to execute the steps of any embodiment of the RER estimation method provided in the embodiment of the present application.

[0086] The storage medium may include: a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0087] Since the instructions stored in the storage medium can execute the steps in any RER estimation method embodiment provided in the embodiments of the present application, the beneficial effects that can be achieved by any RER estimation method provided in the embodiments of the present application can be achieved. Please refer to the previous embodiments for details, which will not be repeated here.

[0088] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for estimating RER based on PetCO2, characterized in that: The method is applied in a host computer, the host computer is connected to a measuring device, and the method comprises: When the user state is in the initial state, a connection signal is sent to the measuring device to connect; When the user state changes from the quasi-expiratory state to the constant-flow exhalation state, the user's real-time exhalation flow and the user's Ef are displayed, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range; When the preset time is reached and the user is in the exhalation state, a stop measurement instruction is sent to the measuring device, and the end-tidal carbon dioxide concentration is calculated based on the real-time exhalation flow; The corresponding RER value is obtained according to the mapping relationship between end-tidal carbon dioxide concentration and RER.

2. The RER estimation method according to claim 1, characterized in that: The mapping relationship between end-tidal carbon dioxide concentration and RER is obtained through user personal information, which includes expiratory flow in constant flow expiratory state, vital capacity in constant flow expiratory state, height, weight, gender, age, race, work and rest habits, time zone, measurement time and mapping relationship table.

3. The RER estimation method according to claim 1, characterized in that: The measuring equipment includes a carbon dioxide sensor and a flow sensor; The absolute error of the carbon dioxide concentration measurement value of the carbon dioxide sensor is 0.5%, the sampling frequency is greater than 5hz, and the response time is less than 500ms; The relative error of the flow measurement value of the flow sensor is 15%, the sampling frequency is greater than 5hz, and the response time is less than 500ms.

4. The RER estimation method according to claim 1, characterized in that: The end-tidal carbon dioxide concentration and RER have a one-to-one mapping relationship.

5. A RER estimation device based on PetCO2, characterized in that: The device comprises: A sending module, used for sending a connection signal to the measuring device for connection when the user state is an initial state; A measurement module, used for displaying the user's real-time exhalation flow and the user's Ef when the user's state is converted from the quasi-exhalation state to the constant-flow exhalation state, so that the difference between the user's real-time exhalation flow and the user's Ef is within a preset threshold range; A calculation module, used to send a stop measurement instruction to the measuring device when a preset time is reached and the user is in the exhalation state, and calculate the end-tidal carbon dioxide concentration according to the real-time exhalation flow; The generation module is used to obtain the corresponding RER value according to the mapping relationship between the end-tidal carbon dioxide concentration and the RER.

6. A computer device, characterized in that: The computer device comprises a processor and a memory, wherein a computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the RER estimation method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, which is loaded and executed by a processor to implement the RER estimation method according to any one of claims 1 to 4.

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