JP7822010B2 - Respiratory function test simulator - Google Patents

Description

The present invention relates to a respiratory function test simulator that simulates respiratory function tests.

Conventionally, there are spirometers capable of measuring vital capacity (VC) and forced vital capacity (FVC) (see, for example, Patent Document 1, Patent Document 2, and Non-Patent Document 1). Among these, there are precision testing devices that can supply test gas (e.g., helium (He)) to the subject and perform precision tests such as functional residual capacity (FRC) (see, for example, Patent Document 2 and Non-Patent Document 1).

JP 2013-153886 A JP 2017-086704 A

Respiratory Function Test Handbook (Japanese Respiratory Society, Pulmonary Physiology Specialist Committee), Medical Review Co., Ltd.

Reliable test results can only be obtained with a spirometer by having the subject inhale and exhale at the appropriate timing and with the appropriate intensity according to the prescribed test procedure. Therefore, it is extremely important that the test procedure and the subject's breathing are appropriate in clinical practice, and these are also included in the scope of questions in the National Medical Laboratory Technologist Examination. Testers must master the test procedures required for each test item and how to instruct the subject to breathe in accordance with those procedures. Given this reality, it is considered preferable for testers to acquire skills not only through classroom learning, but also by actually using a spirometer on a subject.

However, precision testing equipment is more expensive than airflow-type spirometers that use pressure sensors (see, for example, Patent Document 1 and Non-Patent Document 1), and because the number of medical institutions that have introduced it is relatively small, it is difficult to learn the skills using the actual equipment. Furthermore, it is extremely difficult to introduce precision testing equipment into educational institutions, and opportunities for students to experience precision testing are extremely limited. Even if precision testing equipment were available, there are cost issues associated with using testing gas to learn precision testing skills.

The present invention was developed in consideration of the above-mentioned problems, and its purpose is to make it possible to acquire precision testing skills at low cost.

The above-mentioned problems are solved by the following means. Note that, for reference, the reference numerals used in the description and drawings of the embodiments of the invention described below are added in parentheses, but the components of the present invention are not limited to these. Various changes and modifications can be made without departing from the technical scope of the present invention.

The first means is a respiratory function test simulator (1) that simulates detailed tests related to gas concentrations (FRC test, CV test, DLCO test), and is characterized by comprising a measurement unit (flow sensor 10, CPU 53) that measures respiratory flow or respiratory volume (such as a spirogram and spirometry based on the spirogram), an output unit (display 56, speaker 58) that outputs guidance information corresponding to the detailed test (type of gas used in the detailed test, breathing method the subject should follow), and a generation unit (CPU 53) that generates simulation data related to the detailed test based on the data measured by the measurement unit.

The second means is characterized in that, in the first means, the guidance information includes information on the gases used in the detailed examination (He in the case of an FRC examination, _O2 in the case of a CV examination, and a four-type mixed gas in the case of a DLCO examination), and breathing information to be instructed to the subject in the detailed examination (resting ventilation in the case of an FRC examination, exhalation up to the maximum expiratory position and maintaining the expiratory flow rate within a predetermined range in the case of a CV examination, inhalation up to the maximum inhalation position and breath holding at the maximum inhalation position and exhalation in one go in the case of a DLCO examination).

The third means is characterized in that, in the first means, the generation unit generates a gas concentration curve based on data measured by the measurement unit (actual measurement data) and predetermined values corresponding to the detailed examination (reference values calculated using a reference value prediction formula based on the subject's data).

The fourth means is characterized in that, in the third means, the generation unit is capable of generating a first gas concentration curve based on data measured by the measurement unit (actual measurement data) and a first predetermined value calculated based on a prediction formula corresponding to the detailed examination (a reference value calculated using a reference value prediction formula based on the subject's data), and generates a second gas concentration curve having a degree of suitability different from that of the first gas concentration curve based on data measured by the measurement unit (actual measurement data) and a second predetermined value corresponding to the detailed examination that is different from the first predetermined value (for example, a set value obtained by multiplying the reference value by a predetermined coefficient).

The fifth means is any one of the first to fourth means, characterized in that the detailed examination is a functional residual capacity test (FRC), the guidance information includes information notifying the use of He and information instructing quiet ventilation, and the generation unit generates a gas concentration curve indicating the He concentration.

The sixth means is any one of the first to fourth means, wherein the detailed examination is a closing volume test (CV), the guidance information includes information notifying the use of _O2 , information instructing exhalation up to the maximum expiratory level, and information instructing maintenance of the expiratory flow rate within a predetermined range, and the generation unit generates a gas concentration curve indicating the _N2 concentration.

The seventh means is any one of the first to fourth means, wherein the detailed examination is a pulmonary diffusion test (DLCO), the guidance information includes information notifying the use of a four-type mixed gas containing CO, He, O2 _{, and N2} , information instructing the subject to inhale up to the maximum inspiratory position, information instructing the subject to hold their breath for a predetermined period at the maximum inspiratory position, and information instructing the subject to exhale in one breath, and the generation unit generates a gas concentration curve indicating the CO concentration.

The eighth means is a program executed by a respiratory function test simulator (1) that simulates detailed tests related to gas concentrations (FRC test, CV test, DLCO test), and is characterized by measuring respiratory flow or respiratory volume (spirogram, spirometry based on the spirogram, etc.) using a measurement unit (flow sensor 10, CPU 53), outputting guidance information corresponding to the detailed test (type of gas used in the detailed test, breathing method the subject should follow) using an output unit (display 56, speaker 58), and generating simulation data related to the detailed test using a generation unit (CPU 53) based on the data measured by the measurement unit.

This invention makes it possible to acquire precision testing skills at low cost.

FIG. 1 is a diagram illustrating an example of a respiratory function test simulator according to the present embodiment. FIG. 1 is a diagram showing a comparison example between spirometry and detailed examination items. FIG. 10 is a diagram showing an example of a He concentration curve in an FRC test. 10 is a flowchart illustrating an example of a simulation procedure for an FRC inspection. FIG. 10 is a diagram showing an example of calculation of He concentration. FIG. 10 is a diagram showing an example of a simulation result of an FRC inspection. FIG. 10 is a diagram showing an example of an _N2 concentration curve in a CV test. 10 is a flowchart illustrating an example of a simulation procedure for a CV inspection. FIG. 10 is a diagram showing an example of a waveform of dummy data. FIG. 10 is a diagram showing an example of a volume curve in a DLCO test. 10 is a flowchart illustrating an example of a simulation procedure for a DLCO inspection. FIG. 10 is a diagram showing an example of a CO concentration curve in a DLCO test. FIG. 10 is a diagram showing an example of the results of a questionnaire regarding detailed examinations. FIG. 10 is a diagram showing an example of a method for generating an _N2 concentration curve. FIG. 10 is a diagram showing an example of a method for generating an _N2 concentration curve.

The following describes the embodiments in detail with reference to the attached drawings.

[Measurement function of the respiratory function test simulator]
1 is an explanatory diagram showing a respiratory function test simulator 1 according to this embodiment. In this embodiment, a flow sensor type spirometer is used as the respiratory function test simulator 1. Therefore, although it does not have the function of supplying test gas to the subject (nor a sensor for measuring gas concentration), it is at least capable of measuring a spirogram (time-airflow curve), and can obtain VC, FVC, forced expiratory volume in 1 second (FEV ₁ ), and fractional expiratory volume in 1 second (FEV ₁ /FVC).

The respiratory function test simulator 1 is equipped with a respiratory function test flow sensor (hereinafter referred to as "flow sensor") 10. The flow sensor 10 is a flow detection unit that is attached to the subject's mouth and measures the subject's inspiratory flow rate and expiratory flow rate. The information (signal) detected by the flow sensor 10 is a pressure differential signal (differential pressure signal before and after resistor 14) that has a one-to-one relationship (linear relationship) with the flow rate. This differential pressure signal is input into the main body 50 and converted into a corresponding flow rate signal based on this differential pressure signal.

The flow sensor 10 is composed of a resistor 14 that generates a pressure drop for inhalation and exhalation, a first pressure detection port 5a that detects the pressure (static pressure) on the subject side of the resistor 14, and a second pressure detection port 5b that detects the pressure (static pressure) on the opposite side of the resistor 14 from the subject. The resistor 14 generates a pressure difference (differential pressure) between the front and rear of the resistor 14 as the exhalation and inhalation air passes through it.

The main body 50 includes a first pressure transmission tube 51a that transmits the pressure detected at the first pressure detection port 5a to the differential pressure sensor 51, a second pressure transmission tube 51b that transmits the pressure detected at the second pressure detection port 5b to the differential pressure sensor 51, a differential pressure sensor 51 that converts the differential pressure across the resistor 14 into a corresponding electrical signal, an A/D converter 52 that converts the electrical signal (analog signal) output by the differential pressure sensor 51 into a predetermined digital signal, and a digital signal processing unit 53 that executes a measurement program and calculates the pressure of inhalation and exhalation based on the converted digital signal. It is equipped with a CPU 53 that calculates the flow rate, etc.; a RAM 54 that temporarily stores a digital signal related to the output signal of the differential pressure sensor 51 output by the A/D converter 52; a ROM 55 that stores measurement programs and measurement data, including a calibration formula (relationship formula) between the flow rate and the output voltage of the differential pressure sensor 51; a display 56 that displays operation icons and measurement data, etc.; a D/A converter 57 that generates an analog voltage corresponding to the digital signal from the CPU 53; and a speaker 58 that outputs operation guidance, etc. by voice.

Measurement data such as flow rate and volume stored in ROM 55 is sent to the controller 56a of the display 56. The controller 56a drives the LCD driver 56b based on control signals from the CPU 53, causing the display 56 to display measurement data such as spirograms. The display 56 is equipped with multiple touch sensors (not shown), and the examiner can operate them to start and end measurement programs, input (including selection) measurement parameters, and so on.

[Simulation function of the respiratory function test simulator]
The respiratory function test simulator 1 of this embodiment is capable of measuring a spirogram as described above, and is also capable of simulating tests that are normally performed using precision testing devices (Patent Document 2, Non-Patent Document 1). A simulation program for the precision test is stored in the ROM 55, and is executed by the CPU 53 based on the operation of the examiner.

Figure 2 explains the difference between spirometry, a test item that can be obtained from a spirogram, and the test items of a detailed examination performed by supplying gas to the subject. Spirometry can be measured using, for example, a flow sensor-type spirometer (see Patent Document 1), and is intended for screening for obstructive respiratory disorders and restrictive respiratory disorders. Spirometry includes VC, FVC, forced expiratory volume in one second, and fractionalized rate in one second, as well as flow-volume curves. Because the gas inhaled by the subject is room air, the device can be made small and lightweight, and each test item is measured based on the airflow detected by the flow sensor.

On the other hand, detailed examination items can be measured using a volumetric spirometer (also called a rolling seal spirometer), which allows the subject to inhale test gas supplied into a cylinder by moving a bell inside the cylinder in response to the subject's breathing, as shown in Patent Document 2 and Non-Patent Document 1. The purpose of the detailed examination is to evaluate lung volume fraction, ventilation maldistribution, and gas exchange disorders. Spirometry can also be measured using a volumetric spirometer. Detailed examination items include functional residual capacity (FRC), closing volume (CV), and pulmonary diffusion capacity (DLCO). FRC is performed by having the subject inhale a He-mixed gas, and the He concentration is measured using a He sensor. CV is performed by having the subject inhale 100% _O2 , and the _N2 concentration corresponding to the residual volume is measured using an _N2 sensor. DLCO is performed by having a subject inhale a four-gas mixture (He, CO, O ₂ , N ₂ ), with the He concentration being measured by a He sensor and the CO concentration being measured by a CO sensor.

As shown in Figure 2, detailed examination items cannot be measured using a flow sensor type spirometer. Therefore, technical skills would normally have to be acquired using an air volume type spirometer. However, in this embodiment, as shown below, the flow sensor type spirometer is equipped with a detailed examination simulation function, making it possible to acquire detailed examination skills without using an air volume type spirometer.

In this embodiment, in simulating a detailed examination, rather than simply displaying pre-set pseudo data, simulation data is generated based on actual spirograms obtained from subjects, making it possible to present simulation data that closely resembles the behavior of actual data from subjects in clinical settings. This allows for efficient learning of examination techniques.

The following formula shows an example of a method for calculating the gas concentration in this embodiment.
Y=aX+b...(Formula 1)

Y is the measured value, X is the gas concentration, a is the coefficient, and b is the intercept. In this way, when an equation relating the measured value and the gas concentration is defined, the predicted value (which can also be called the reference value) obtained by the reference value prediction equation based on the subject's actual data (age, sex, height, etc.) is used as the measured value, and the gas concentration can be back-calculated. A gas concentration change curve can be generated and displayed based on the back-calculated gas concentration and the actually measured spirogram. Note that in the example of (Equation 1), the relationship between the measured value and the gas concentration is defined as a linear function, but it is not limited to this and can also be defined as another function such as a quadratic function or a logarithmic function.

(FRC inspection simulation)
The principle of FRC testing is that the lungs are connected to a circuit of known volume containing a known concentration of an indicator gas, and the subject is instructed to breathe repeatedly. By thoroughly mixing the gases in both spaces, FRC can be calculated from the change in the concentration of the indicator gas. Helium (He), which is not absorbed by the lungs, is often used as the indicator gas. As the subject rebreathes at a quiet expiration position until the He concentration reaches equilibrium, the He concentration curve gradually decreases from its peak with each quiet ventilation, converging to the equilibrium concentration, as shown in Figure 3. This He concentration curve is reproduced in the FRC test simulation.

4 is a flowchart corresponding to the FRC inspection simulation. When the inspector selects an object displayed on the display 56 that will execute the FRC inspection simulation, the CPU 53 executes the simulation program and the FRC inspection simulation is performed. The display 56 displays a message prompting the inspector to prepare an _O2 /He mixed gas, which is the FRC inspection gas (S110). Also, a "Start Preparation" button is displayed for filling the cylinder with the inspection gas and preparing for FRC measurement (S120). From this information, the inspector can understand the type of inspection gas to be used in FRC measurement.

When the examiner operates the "Start preparation" button, the messages "Breathing circuit ventilation in progress" and "Gas injection in progress" are displayed on the display 56 (S130). As mentioned above, the respiratory function test simulator 1 is a flow sensor-type spirometer and does not have a gas supply function, so these displays are simulated. However, the examiner can understand the process of the test gas being filled into the cylinder prior to the start of measurement. It is also possible to more closely resemble a real test environment by outputting a simulated sound of the test gas being filled into the cylinder from the speaker 58.

After the messages "Breathing circuit ventilation in progress" and "Gas injection in progress" have finished being displayed (after gas injection is complete), the examiner operates the "Start measurement" button displayed on the display 56 (S140), and the flow sensor 10 provided in the respiratory function test simulator 1 measures the subject's actual spirogram and displays it on the display 56 (S150). Furthermore, the display 56 displays the message "Please perform quiet ventilation" (S160). This allows the examiner to understand the process of having the subject inhale the test gas through quiet ventilation during the FRC test.

Next, as described above, the CPU 53 calculates the predicted FRC value (which may also be called the FRC reference value) using a reference value prediction formula based on the subject's actual data (age, sex, height, weight, etc.). This reference value prediction formula may use the formula disclosed in Non-Patent Document 1. Note that the reference value prediction formula (reference value prediction formula for FRC, as well as CV and DLCO, described below) is not limited to that disclosed in Non-Patent Document 1, and other prediction formulas may also be used. Furthermore, the subject's actual data required for the reference value prediction formula may include not only age, sex, height, and weight, but also other data such as body surface area (BSA).

The following equation shows the relationship between the He concentration, the circuit capacitance, and the FRC.
C1 (He concentration in the circuit before measurement starts) × (circuit capacity)
= C2 (He concentration after equilibrium) × (circuit capacity + FRC) ... (Equation 2)

In this embodiment, the He concentration in the circuit before measurement begins is assumed to be 11%, and the calculated predicted FRC value is used as the FRC in (Equation 2) to calculate the He concentration. In the example of Figure 5(a), the circuit volume before measurement begins (before He inhalation) is shown as the FRC dead space volume, which is 10.50 L. The amount of He in the circuit before measurement begins is 11% x 10.50 L = 1.155 L. Meanwhile, the subject's FRC calculated based on the prediction equation is 3.38 L, and because the subject did not inhale He before measurement began, the He concentration in the lungs is 0%, and the amount of He in the lungs is 0.0 L. In this case, the sum of the amount of He in the circuit and the amount of He in the lungs is 1.155 L.

As shown in Figure 5(b), when the subject inhales, the TV (in this case, TVI, which is equivalent to the inhaled volume of the tidal volume) is subtracted from the FRC dead space volume, and the TV (in this case, TVI) is added to the FRC. In this example, 0.50 L is inhaled, resulting in 0.50 L x 0.11% = 0.055 L being taken into the lungs, the He concentration changing from 0% to 1.42%, and the amount of He in the circuit becoming 10.00 L x 11% = 1.10 L.

Next, as shown in Figure 5(c), when the subject exhales, the amount equivalent to TV (in this case, TVE, which is equivalent to the exhaled volume of the tidal volume) is subtracted from FRC + TV, and the amount equivalent to TV (in this case, TVE) is added to the FRC dead space volume after the subtraction. In this example, 0.50 L is exhaled, and 0.50 L x 1.42% = 0.0071 L of He is returned to the circuit, bringing the amount of He in the circuit to 1.1071 L, or 10.54%.

As shown in Figure 6, by repeating the gas concentration calculations in Figures 5(b) and 5(c) in accordance with the subject's actual exhalation and inhalation, the He concentration displayed on display 56 gradually decreases and eventually reaches a stable equilibrium state (the rate of decrease in He concentration falls within a predetermined range). In this example, as shown in Figure 5(d), the He concentration stabilizes when the He concentration in the circuit and lungs reaches 8.33%, and the total amount of He in the circuit and lungs remains at 1.155 L. In this way, the examiner can understand how the He concentration changes as the subject repeats quiet ventilation in a simulated FRC test (see Figure 6).

Returning to FIG. 4, if the He concentration recalculated in accordance with the subject's quiet ventilation is stable (YES in S190), the CPU 53 displays "He concentration is stable" on the display 56 to notify the user that the FRC test is ending (S191). Then, the CPU 53 displays the test results (e.g., the calculated predicted FRC value and other test results obtainable from the FRC test) on the display 56 (S200), and ends the simulation of the FRC test.

On the other hand, as described below, if the He concentration does not stabilize even after waiting for a predetermined period of time due to an FRC value being set (an unsatisfactory setting) that differs from the value predicted by the reference value prediction formula (reference value) (NO in S190), the CPU 53 displays an "End Measurement" button on the display 56 to end the FRC test (S192). Based on the examiner's operation of the "End Measurement" button, the test result (which may be the set FRC value or a result indicating that the FRC could not be measured appropriately) is displayed on the display 56 (S200), and the FRC test simulation ends.

In addition, if a detailed examination item cannot be measured properly, such as when the measurement ends before the He concentration stabilizes in an FRC examination simulation, guidance that the item could not be measured properly may be provided via the display 56 or speaker 58, and further guidance may be provided to record this as a comment in the electronic medical record, etc. (rather than leaving it unrecorded). This allows the examiner to understand what to do if the measurement ends with an irregular result.

In the example of Figure 6, the He concentration decreases smoothly and reaches a state of equilibrium, and the TV shown by the spirogram is stable at a constant amplitude. In this embodiment, by using a predicted value as the FRC, it is possible to reproduce a state in which the He concentration decreases smoothly and stabilizes through repeated quiet ventilation.

On the other hand, if the obstruction is severe, the He concentration will decrease to a certain extent, but it may take a long time for it to stabilize from there. In this embodiment, as mentioned above, the predicted FRC value is used, but by setting an FRC value different from the predicted FRC value (for example, an FRC set value obtained by multiplying the predicted FRC value by 1.2 as a coefficient), it is possible to reproduce the He concentration when the obstruction is severe. In this way, the examiner can experience both good and bad examples of FRC testing.

(CV inspection simulation)
CV testing is a respiratory function test that detects uneven distribution of inspired air by washing out an indicator gas from the lungs. The indicator gas typically used is nitrogen ( _N2 ). Figure 7 shows the details of the _N2 concentration curve in a CV test. The _N2 concentration curve in a CV test is a single-exhalation curve divided into phases 1 to 4. Phase 1 represents dead space air containing 100% O2 only, phase ₂ represents a mixture of dead space air and alveolar air, phase 3 represents alveolar air, and phase 4 represents CV. Phase 3 exhibits a flat curve and is called the alveolar plateau. Pulsatile waves consistent with cardiac beats are observed in this phase. When alveolar air from various locations contributes to exhalation at a constant rate, the alveolar plateau is formed. In phase 4, the _N2 concentration rises rapidly toward the maximum expiratory level. The lung volume (expiratory volume) in phase 4 is the CV.

8 is a flowchart corresponding to the simulation of a CV test. When the examiner selects an object displayed on the display 56 that will execute the CV test simulation, the CPU 53 executes the simulation program and the CV test simulation is performed. A message prompting the examiner to prepare _O2 , which is the inhalation gas, is displayed on the display 56 (S210). Also, a "Start Preparation" button is displayed to fill the cylinder with the inhalation gas and prepare for CV measurement (S220). From this information, the examiner can understand the type of gas used in CV measurement.

When the examiner operates the "Start preparation" button, the messages "Respiratory circuit ventilation in progress" and "Gas injection in progress" are displayed on the display 56 (S230). After the messages "Respiratory circuit ventilation in progress" and "Gas injection in progress" have finished being displayed (after gas injection is complete), the examiner operates the "Start measurement" button displayed on the display 56 (S240), and the subject's actual spirogram is measured by the flow sensor 10 provided in the respiratory function test simulator 1 and displayed on the display 56 (S250). In addition, the message "Please perform quiet ventilation" is displayed on the display 56 (S260).

Next, as described above, the CPU 53 calculates a predicted CV value (which may also be called a CV reference value) using a reference value prediction formula based on the actual data of the subject (age, sex, etc.). This reference value prediction formula may be the formula disclosed in Non-Patent Document 1. Next, the CPU 53 performs a calculation to stretch or contract the dummy data of the _N2 concentration curve prepared in advance, shown in Figure 9, in the direction of the expiratory volume, corresponding to the actual VC value (for example, the value of a VC test performed prior to the CV test simulation) or the predicted VC value calculated using the reference value prediction formula based on the subject's data.

Here, for the fourth phase, a calculation is performed to expand or contract the data in the direction of the expiratory volume according to the predicted CV value, and this expansion or contraction is absorbed by expanding or contracting the third phase. Note that if the expiratory volume assumed in the dummy data matches the actually measured VC or predicted VC value, there is no need to expand or contract the dummy data. Also, if the CV assumed in the dummy data matches the predicted CV value, there is no need to expand or contract the fourth phase.

Alternatively, standard dummy data may be prepared (stored in ROM 55) for each subject's data (age, gender, height, etc.), and dummy data corresponding to the actual subject's data (age, gender, height, etc.) may be selected and expanded/contracted. In this manner, the expanded/contracted dummy data is temporarily set as the _N2 concentration curve (S270). Alternatively, multiple dummy data corresponding to VC (e.g., four values of VC = 2.5 L, 3.5 L, 4.5 L, and 5.5 L) may be prepared, and dummy data closest to the actual subject's VC may be selected and expanded/contracted.

In addition, one may be selected from multiple base waveforms (e.g., five: CV1, CV2, CV3, CV4, and CV5), and the selected base waveform may be expanded or contracted in the direction of the expiratory volume according to the actually measured expiratory volume. For example, for each measurement, one may be selected from multiple base waveforms in a predetermined order (e.g., CV1 → CV2 → CV3 → CV4 → CV5), or one may be selected based on a random number.

Then, a message encouraging the subject to exhale up to the maximum expiratory level, "Please exhale slowly until you can no longer exhale," is displayed on the display 56 (S280). Next, a message encouraging the subject to inhale up to the maximum inhalation level, "Please inhale slowly and fully until you can no longer exhale," is displayed on the display 56 (S290). This message encourages the subject to inhale oxygen.

Next, the CPU 53 causes the display 56 to display a message encouraging the user to exhale to the maximum expiratory level, saying, "Exhale slowly until you can no longer exhale" (S300). The CPU 53 then causes the display 56 to display the flow actually measured by the flow sensor, and also causes the display 56 to display a message instructing the user to maintain the exhalation rate within a predetermined range, saying, "Maintain the exhalation rate in the range of 0.3 to 0.5 L/s" (S310).

The CPU 53 also generates an _N2 concentration curve in response to an increase in the exhaled air volume based on the spirogram actually measured in the CV test simulation (S320). The _N2 concentration curve is generated by tracing a provisionally set, non-displayed _N2 concentration curve in accordance with the exhaled air volume being measured (displaying the _N2 concentration at a point corresponding to the exhaled air volume). This makes it appear as if the _N2 concentration is changing in real time. For example, with regard to the third phase, the third phase may be terminated (the provisionally set third phase portion of the dummy data may be extended or shortened) and the fourth phase may be initiated (the provisionally set fourth phase portion of the dummy data may be extended or shortened and tracing may be initiated) when the exhaled air flow (flow measured by the flow sensor) being measured falls below a predetermined value (e.g., less than 0.2 L/s).

Then, based on the detection of inhalation after the end of exhalation up to the maximum expiratory level (S330), the CPU 53 ends the generation of the _N2 concentration curve, displays the test results (for example, the calculated CV predicted value and other test results that can be obtained in the CV test) on the display 56 (S340), and ends the simulation of the CV test.

In this embodiment, as described above, the CV predicted value is used to provisionally set the _N2 concentration curve, but by setting a CV value different from the CV predicted value (for example, a CV set value obtained by multiplying the CV predicted value by 1.2 as a coefficient), the CV of the fourth phase can be increased and the _N2 concentration in the case of severe obstruction can be reproduced. In this way, the examiner can experience both good and bad cases in CV examinations.

(Simulation of DLCO inspection)
Figure 10 is an explanatory diagram showing details of the volume curve in a DLCO test. In the DLCO test, the subject inhales a four-component gas mixture containing CO, He, O2 _{, and N2} (e.g., 0.3%, 10%, 21%, and 68.7%) from the maximum expiratory level (RV level). After holding their breath for 10 seconds, the first 750 mL, which is affected by dead space, is discarded, and 0.5 to 1 L of alveolar air is collected and analyzed. The CO concentration in exhaled alveolar air (FACO) relative to the CO concentration in inhaled air (FICO) and the He concentration in exhaled alveolar air (FAHe) relative to the He concentration in inhaled air (FIHe) are measured and compared.

In this embodiment, the He concentration curve and the CO concentration curve are generated by the following methods, which are outlined in (1) to (9).
(1) DLCO is a predicted value (reference value). (2) VI (inspiratory vital volume during DLCO measurement) uses actual measurement data obtained during measurement. VI in DLCO testing can be said to be the inhaled volume when a four-component gas mixture is inhaled in one go from the maximum expiratory level (RV level). (3) VA (alveolar volume under standard conditions (STPD)) is calculated from VI and RV (residual volume). (4) RV (residual volume) is a predicted value (reference value). (5) FIHe (He concentration in inhaled gas) is the initial He concentration setting. (6) FICO (CO concentration in inhaled gas) is the initial CO concentration setting. (7) FAHe (He concentration in exhaled alveolar gas) is calculated by back-calculating from VA using the VA' formula. (8) FACO (CO concentration in exhaled alveolar gas) is calculated by back-calculating from the DLCO formula. (9) The gas distribution concentration is changed and displayed based on the following (Equation 3-1) and (Equation 3-2) so that it converges to the calculated FAHe and FACO.
The concentration curve is obtained by multiplying the difference concentration between FI and FA by (1-EXP (-elapsed time/time constant)) and subtracting the result from FI. That is,
Current He gas concentration=FIHe−(FIHe−FAHe)×(1−EXP(−elapsed time÷He time constant)) (Equation 3-1)
Current CO gas concentration = FICO - (FICO - FACO) x (1 - EXP (- elapsed time ÷ CO time constant)) (Equation 3-2)
It is expressed as:

The DLCO calculation formula is shown below.
DLCO=[VA×1000×60/((PB-47)×BHT)]×ln(FACO(0)/FACO)...(Formula 4)
Here, BHT is the breath-hold time and is a fixed value (10.0 seconds). Note that BHT is not limited to 10.0 seconds and may be other times. PB is atmospheric pressure (a fixed value (760 Torr) or a manually set value). The value 47 to be subtracted is the saturated water vapor partial pressure at 37°C. FACO(0) is the alveolar CO concentration immediately after CO inhalation.
where:
FACO(0)=(FAHe/FIHe)×FICO...(Formula 4-1)
VA(BTPS)=(VI+RV)...(Formula 4-2)
VA'(BTPS)=(VI×(FIHe/FAHe)-VD)...(Formula 4-3)
is established.

Using known parameters from the DLCO calculation formula (Equation 4), the FAHe concentration and FACO concentration are back-calculated. VA (standard state (STPD) alveolar volume) is calculated from the VI obtained during measurement and the predicted RV (residual volume) value as follows:
VA=(VI+RV)...(Formula 4-4)
Furthermore, VA=VA' is set, and FAHe is calculated backward from the VA' formula.
FAHe=FIHe×(VA'/VI)...(Formula 4-5)
The obtained FAHe is used to obtain FACO(0).
FACO(0)=(FAHe/FIHe)×FICO...(Formula 4-6)

The FACO is back-calculated using the DLCO prediction and BHT.
D1=(VA×1000×60)/((PB-47)×BHT)…(Formula 4-7)
D2=exp(DLCO/D1)...(Formula 4-8)
FACO=FACO(0)/D2...(Formula 4-9)

Figure 11 is a flowchart corresponding to the DLCO test simulation. For example, when the examiner selects an object displayed on the display 56 that will execute a DLCO test simulation, the CPU 53 executes the simulation program and the DLCO test simulation is performed. A message prompting the examiner to prepare a four-type mixed gas is displayed on the display 56 (S410). In addition, a "Start Preparation" button is displayed to fill the cylinder with inhalation gas and prepare for CV measurement (S420). From this information, the examiner can understand the type of gas to be used in DLCO measurement.

When the examiner operates the "Start preparation" button, the messages "Respiratory circuit ventilation in progress" and "Gas injection in progress" are displayed on the display 56 (S430). After the messages "Respiratory circuit ventilation in progress" and "Gas injection in progress" have finished being displayed (after gas injection is complete), the examiner operates the "Start measurement" button displayed on the display 56 (S440), and the subject's actual spirogram is measured by the flow sensor 10 provided in the respiratory function test simulator 1 and displayed on the display 56 (S450). In addition, the message "Please perform quiet ventilation" is displayed on the display 56 (S460).

Next, the CPU 53 causes the display 56 to display a message encouraging the subject to exhale slowly to the maximum expiratory level, saying, "Exhale slowly until you can no longer exhale," (S490). Next, the CPU 53 causes the display 56 to display a message encouraging the subject to inhale quickly to the maximum inhalation level, saying, "Inhale quickly," (S500). This message encourages the subject to inhale the four-component gas mixture. Next, the CPU 53 causes the display 56 to display a message instructing the subject to hold their breath for the set breath-holding time, saying, "If you can no longer inhale, hold your breath for 10 seconds," (S510).

Next, as described above, the CPU 53 calculates a predicted DLCO value corresponding to the subject's data based on a prediction formula. The predicted value may also be referred to as a reference value. The prediction formula may be, for example, that established by the Japanese Respiratory Society. Then, based on the calculated DLCO predicted value and the actual VI measurement value, the CPU 53 calculates and generates a He concentration curve and a CO concentration curve using the aforementioned formula (S520). As shown in Figure 12, the values of FIHe (cylinder gas concentration set value) and FICO (cylinder gas concentration set value) are used as the He concentration curve and CO concentration curve corresponding to the breath-holding period during which the inspiratory flow measured by the flow sensor does not change. The values of FAHe and FACO calculated as described above are used as the He concentration curve and CO concentration curve corresponding to the exhalation period after breath-holding. In the example shown in Figure 12, the respective concentrations are normalized so that the relative changes in He and CO concentrations can be understood. During the period during which the subject is holding their breath, FIHe is displayed as the He concentration, and FICO is displayed as the CO concentration.

The CPU 53 then displays on the display 56 a message instructing the user to exhale in one go, saying, "Please exhale all at once" (S530). Accordingly, FAHe is displayed as the He concentration, and FACO is displayed as the CO concentration. Then, based on the fact that the expiratory flow has fallen below a predetermined value (S540), the CPU 53 displays the test results (e.g., the calculated DLCO predicted value and other test results obtainable in the DLCO test) on the display 56 (S550), and ends the DLCO test simulation.

In the above embodiment, FIHe is displayed as the He concentration curve and FICO as the CO concentration curve during the breath-holding period, and then FAHe is displayed as the He concentration curve and FACO as the CO concentration curve after exhalation (making it appear as if the curves are being drawn in real time in response to the flow). However, this is not limiting. Alternatively, the He concentration curve and CO concentration curve may not be displayed during the breath-holding period, and after a predetermined time has passed after exhalation (e.g., one to several seconds), the He concentration curve including FIHe and FAHe and the CO concentration curve including FICO and FACO may be displayed. This corresponds to the fact that when measuring DLCO, sample gas from exhalation is sent to the analysis circuit (He concentration sensor, CO concentration sensor), and the first 750 mL is discarded and the gas concentration curves are displayed only after the analysis is completed.

In this embodiment, as described above, the predicted DLCO value is used to generate the CO concentration curve, but by setting a DLCO value different from the predicted DLCO value (for example, a set DLCO value obtained by multiplying the predicted DLCO value by 0.8 as a coefficient), it is possible to reproduce the CO concentration when gas exchange function is impaired. In this way, the examiner can experience both good and bad examples of DLCO testing.

As described above, this embodiment allows participants to acquire testing techniques for detailed tests that require the ability to supply test gas to subjects and detect gas concentrations, without the need to actually use test gas, making it possible to acquire testing techniques at low cost.

The simulation function of this embodiment also has the ability to provide guidance on the test procedures for detailed examination items (e.g., FRC, CV, DLCO), allowing users to learn the procedure that must be followed for each test item. Furthermore, by providing guidance on the type of gas used in the test and the breathing method that the subject should follow in accordance with the test procedure, users can learn what gases should be prepared and how the subject should breathe for each test item.

In addition, the simulation function of this embodiment simulates gas concentration curves during detailed examinations based on the respiratory flow rate or respiratory volume (spirogram) that is actually measured, making it possible to present data that is closer to the actual examination environment to the examiner, which provides a more realistic experience and improves learning effectiveness compared to simply presenting predetermined pseudo data. For example, if the examinee is made to breathe inappropriately just for training purposes, an appropriate gas concentration curve will not be obtained, so the examiner can recognize the importance of having the examinee breathe accurately.

Furthermore, this embodiment makes it possible to simulate both good and bad test results, allowing users to become familiar with the diverse test results that occur in clinical settings.

Figure 13 shows how the attitudes of the examiners changed after undergoing the test simulations (training) for FRC, CV, and DLCO. For each detailed test item, many examiners felt that the test was not easy before the test simulation was performed. However, after the test simulation was performed, an increasing number of examiners felt that the detailed test was easier than expected, thanks to having experienced the test procedure and the breathing method that should be instructed to the examinee, and being presented with a gas concentration curve based on actual measurement data. In this way, by eliminating the perception that the detailed test is difficult, the detailed test can be performed accurately using the detailed testing equipment without confusion in the clinical setting.

As an example, as seen in the strained medical system during the COVID-19 pandemic, even if a significant number of advanced medical devices are introduced, if there is a shortage of examiners who can operate them properly, the strained situation will not improve at all. From this perspective, it is desirable to make some progress in acquiring precision testing skills even before precision testing equipment is introduced. The respiratory function testing simulator of this embodiment also contributes to solving such problems.

(Other forms)
In the above embodiment, an example was described in which the respiratory function test simulator was a flow sensor-type spirometer. However, the respiratory function test simulator is not limited to this, and may be a precision testing device (air volume spirometer (rolling seal spirometer)) having a test gas supply function and a gas concentration detection function. For example, the precision testing device may be controlled to either (1) an actual measurement mode in which gas is actually supplied to the subject using the test gas supply function and the gas concentration is detected using the gas concentration detection function, or (2) a simulation mode in which no gas is supplied to the subject and no gas concentration is detected, and the simulation program of the above embodiment may be executed in (2) the simulation mode. Even in this configuration, since no actual test gas is used, it is possible to acquire precision testing techniques at low cost.

In the above embodiment, an example has been described in which the respiratory function test simulator simulates He concentration, _N2 concentration, and CO concentration, but the respiratory function test simulator is not limited to this, and may also simulate NO (nitric oxide) in exhaled breath. For example, the respiratory function test simulator may simulate an NO concentration curve in exhaled breath based on a relational expression that the lower the values of spirometry items such as VC, FVC, forced expiratory volume in one second, and forced expiratory volume in one second, the higher the NO concentration in exhaled breath.

In the above embodiment, an example has been described in which the parameters measurable by the respiratory function test simulator are respiratory flow rate or respiratory volume obtainable by a flow sensor, and the parameters to be simulated are gas concentrations. However, the present invention is not limited to this configuration. The parameters measurable by the respiratory function test simulator may be parameters other than respiratory flow rate or respiratory volume, and the parameters to be simulated may be parameters other than gas concentrations. For example, the chest and abdomen of a sleeping subject may be imaged with a video camera, and the respiratory rate and arterial oxygen saturation (SpO2) may be simulated based on a relationship between feature values based on the actual image of the chest and abdomen and the respiratory rate, arterial oxygen saturation ( _SpO2 ), etc., in a sleep apnea test ( _PSG ). This makes it possible to simulate a PSG test remotely without installing an actual PSG device on the subject's side.

In the above embodiment, an example was described in which the He concentration at functional residual capacity was simulated using the gas dilution method, but the present invention is not limited to this. It is also possible to simulate intraoral pressure in a functional residual capacity test (body plethysmography) using a body plethysmograph (also called a body box). It is also possible to simulate airway resistance using a body plethysmograph. This makes it possible to acquire testing techniques for test items that use a body plethysmograph, without actually purchasing an expensive and large body plethysmograph.

In the above embodiment, the _N2 concentration curve is generated by tracing a provisionally set, non-displayed _N2 concentration curve in accordance with the exhaled air volume being measured. However, as shown in FIGS. 14 and 15, the provisionally set _N2 concentration curve may be configured based on a predicted value of TLC (total lung capacity) and an average exhaled _N2 concentration calculated from the TLC calculation formula.

The TLC calculation formula is shown below.
TLC=[(VI×FAN ₂ )−(Vd×FA′N ₂ )]÷(FAN ₂ −FEN ₂ )…(Formula 5)
where:
VI: Inhalation volume Vd: Dead space volume (anatomical dead space volume + mechanical dead space volume)
FAN ₂ : Alveolar air _N2 concentration (80%)
_FA'N2 : Exhaled _N2 concentration (corrected for dilution due to dead space)
FEN ₂ : average exhaled N ₂ concentration.

From equation (5), (Vd×FA′N ₂ ) can be omitted because it does not have a significant visual impact in a simulation that displays the N ₂ concentration curve in real time.
(FAN ₂ - FEN ₂ ) = (VI x FAN ₂ ) ÷ TLC... (Formula 5-1)
FEN ₂ = FAN ₂ - ((VI×FAN ₂ )÷TLC) ... (Formula 5-2)
holds true.

Then, as shown in FIG. 14(a), an _N2 concentration curve is constructed based on the average exhaled _N2 concentration calculated using Equation 5-2. The _N2 concentration curve at this stage shows a constant value corresponding to the calculated average exhaled _N2 concentration. Next, as shown in FIG. 14(b), the slope of the third phase is calculated based on the predicted _ΔN2 value, and a third phase portion corresponding to the calculated slope is added to the constant value portion of FIG. 14(a), resulting in an increase in the _N2 concentration from the third phase onward. Here, as the third phase and subsequent portions are added, the entire _N2 concentration curve is adjusted toward the _N2 concentration (e.g., moved in the direction of decreasing _N2 concentration) so that the average exhaled _N2 concentration does not increase above the calculated value but remains at the calculated value. Furthermore, as shown in FIG. 14(c), a fourth phase portion is added to the third phase portion, resulting in a rapid increase in the _N2 concentration in the fourth phase corresponding to the end-tidal pressure. The appearance (starting point) of the fourth phase may be set based on the CV/VC predicted value and the CV predicted value. The waveform of the added fourth phase may be a waveform in which the _N2 concentration increases at a constant rate with respect to the gradient of the third phase.

Next, as shown in Figure 15(d), the first and second phases are added to the third and subsequent phases. The added first and second phase waveforms are, for example, stretched or shortened versions of standard waveform patterns prepared in advance. This completes the provisionally set _N2 concentration curve.

As described above, the _N2 concentration curve is generated by tracing a provisionally set, hidden _N2 concentration curve in accordance with the exhaled air volume being measured (displaying the _N2 concentration at a point corresponding to the exhaled air volume). Here, as shown in FIG. 15( e), during the CV simulation period (the period during which the subject is actually exhaling), a waveform simulating cardiac oscillation with a period of 60 to 90 bpm (1.0 to 1.5 Hz) may be displayed during the third phase display. For example, the period and amplitude of each waveform corresponding to cardiac oscillation may be determined based on random numbers generated within a predetermined range. This allows the examiner to experience the appearance of cardiac oscillation during CV measurement.

1 Respiratory function test simulator 10 Flow sensor 14 Resistor 5a First pressure detection port (pressure detection unit)
5b Second pressure detection port (pressure detection section)
50 Main body 51 Differential pressure sensor 52 A/D converter 53 CPU
54 RAM
55 ROM
56 Touch panel display 57 D/A converter 58 Speaker

Claims (8)

A respiratory function test simulator that performs a simulation of a detailed test regarding gas concentration,
A measurement unit for measuring respiratory flow rate or respiratory volume;
an output unit that outputs guidance information corresponding to the detailed examination;
a generating unit that generates simulation data related to the detailed examination based on the data measured by the measuring unit;
A respiratory function test simulator comprising: 2. The respiratory function test simulator according to claim 1,
The guidance information includes information on a gas used in the detailed examination and information on breathing instructions to be given to the subject during the detailed examination.
Respiratory function test simulator. 2. The respiratory function test simulator according to claim 1,
the generating unit generates a gas concentration curve based on the data measured by the measuring unit and a predetermined value corresponding to the detailed examination.
Respiratory function test simulator. 4. The respiratory function test simulator according to claim 3,
The generation unit
a first gas concentration curve can be generated based on the data measured by the measurement unit and a first predetermined value calculated based on a prediction formula corresponding to the detailed examination;
generating a second gas concentration curve having a degree of suitability different from that of the first gas concentration curve based on the data measured by the measurement unit and a second predetermined value corresponding to the detailed inspection and different from the first predetermined value;
Respiratory function test simulator. The respiratory function test simulator according to any one of claims 1 to 4,
The detailed test is a functional residual capacity test (FRC),
the guidance information includes information notifying the use of He and information instructing the patient to perform quiet ventilation;
The generating unit generates a gas concentration curve indicating a He concentration.
Respiratory function test simulator. The respiratory function test simulator according to any one of claims 1 to 4,
The detailed examination is a closing volume examination (CV),
the guidance information includes information informing the user of the use of _O2 , information instructing the user to exhale up to a maximum expiratory level, and information instructing the user to maintain an expiratory flow rate within a predetermined range;
The generating unit generates a gas concentration curve indicating the _N2 concentration.
Respiratory function test simulator. The respiratory function test simulator according to any one of claims 1 to 4,
The detailed examination is a pulmonary function diffusion test (DLCO),
the guidance information includes information informing the user of the use of a four-component mixed gas containing CO, He, O2 _{, and N2} , information instructing the user to inhale up to a maximum inhalation level, information instructing the user to hold their breath for a predetermined period of time at the maximum inhalation level, and information instructing the user to exhale in one breath;
The generating unit generates a gas concentration curve indicating the CO concentration.
Respiratory function test simulator. A program executed by a respiratory function test simulator that executes a simulation of a detailed test regarding gas concentration,
measuring a respiratory flow rate or a respiratory volume with a measuring unit;
outputting guidance information corresponding to the detailed examination by an output unit;
and generating, by a generating unit, simulation data relating to the detailed examination based on the data measured by the measuring unit.