JP2017161263A - End expiratory measurement device and end expiratory measurement method - Google Patents

Abstract

An object of the present invention is to provide an end-expiration measuring device capable of measuring a specific gas component in end-expiration with high accuracy. An end-breath measuring device for measuring the concentration of a specific gas component in end-expiration, comprising a measurement cell having a flow path through which exhaled air of a subject flows, and exhaled breath flowing through the flow path. a CO2 concentration measuring device for measuring the CO2 concentration in the breath, a gas concentration measuring device for measuring the concentration of the specific gas component in the exhaled breath flowing through the flow path, and the CO2 concentration in the exhaled breath changing at a threshold value or higher. and a measuring unit that obtains the concentration of the specific gas component in the end-expiration from the measured value of the gas concentration measuring device while the patient is in the air. [Selection drawing] Fig. 1

Description

  The present invention relates to an end expiration measurement device and an end expiration measurement method.

  In the human or animal body, gas exchange between atmospheric oxygen and blood carbon dioxide occurs in the alveoli by breathing. In addition, components contained in the venous blood flowing through the alveolar capillaries move into exhaled gas by gas exchange, but are discharged out of the body.

  Therefore, it has been studied to use exhaled breath exhaled from the subject as a specimen for clinical biochemical examination. Since exhaled breath can be easily collected non-invasively unlike blood, it is ideal as a specimen for clinical examination.

  However, the concentration of the specific gas component to be examined in exhaled breath is extremely dilute. In addition, the first part of the exhaled air exhaled from the subject is dead space exhaled air that is discharged outside the body without being used for gas exchange. Therefore, when exhalation is used as a specimen, it is necessary to exclude dead-space exhalation, collect end exhalation used for gas exchange in the alveoli, and measure specific gas components.

  Therefore, exhaled air that is blown from the mouthpiece is discharged to the outside while being measured by a flow sensor provided on the outlet side of the exhalation discharge route, and when the discharge amount exceeds the dead space capacity, exhalation from the middle of the exhalation discharge route There has been proposed a method of collecting end-expiration by collecting a sample by suction (see, for example, Patent Document 1).

  In addition, when a predetermined time has elapsed since the exhalation was blown, the end exhalation is collected and analyzed by switching the exhalation discharge path from the first discharge path to the second discharge path provided with the analysis unit. A method has been proposed (see, for example, Patent Document 2).

JP 2004-77467 A JP 2015-38427 A

  However, because the volume of dead space and the flow rate of exhaled breath vary depending on the subject, if exhaled air is collected based on the flow rate of exhaled air and the time since the exhaled air was blown, the collected exhaled air contains a large amount of dead space exhaled air. The end-expiration may be diluted. For this reason, the measurement accuracy of a specific gas component may fall.

  The present invention has been made in view of the above, and an object of the present invention is to provide an end expiration measurement device capable of measuring a specific gas component in end expiration with high accuracy.

According to one aspect of the present invention, there is provided an end-tidal measurement device that measures the concentration of a specific gas component in end-tidal air, the measurement cell having a flow path through which the subject's exhalation flows, and the flow and CO ₂ concentration measuring device for measuring the CO ₂ concentration in the exhaled breath flowing through the road, and a gas concentration measuring device for measuring the concentration of the specific gas component in the breath flowing through the flow path, CO ₂ of the exhaled breath And a measuring unit that obtains the concentration of the specific gas component in the end-expired breath from the measured value of the gas concentration measuring device while the concentration is transitioning above a threshold value.

  According to the embodiment of the present invention, there is provided an end expiration measurement device capable of measuring a specific gas component in end expiration with high accuracy.

It is a figure which illustrates schematic structure of the end-tidal measurement apparatus in 1st Embodiment. It is a figure which illustrates the function structure of the control apparatus in 1st Embodiment. It is sectional drawing which illustrates the gas sensor in 1st Embodiment. It is a figure which illustrates the flowchart of the end breath measurement process in 1st Embodiment. It is a figure which illustrates the measurement result of carbon dioxide concentration and acetone concentration. It is a figure which illustrates schematic structure of the end-tidal measurement apparatus in 2nd Embodiment. It is a figure which illustrates the function structure of the control apparatus in 2nd Embodiment. It is a figure which illustrates the flowchart of the end breath measurement process in 2nd Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

[First embodiment]
<End-tidal measurement device>
FIG. 1 is a diagram illustrating a schematic configuration of an end-tidal measurement device 11 according to the first embodiment. The end breath measurement apparatus 11 in the present embodiment measures the concentration of a specific gas component in the end breath exhaled from the subject 200.

  As shown in FIG. 1, the end-tidal measurement device 11 includes a measurement cell 101, a control device 150, a power source 160, and a display device 170.

The measurement cell 101 is provided with a flow path 111 through which exhaled air exhaled from the subject 200 flows, a mouthpiece 102, a CO ₂ concentration measuring device 121, and a gas sensor 123 as a gas concentration measuring device.

  The mouthpiece 102 is provided at the end of the flow path 111 and guides exhaled air exhaled from the subject 200 to the flow path 111. The exhaled air exhaled by the subject 200 from the mouthpiece 102 to the flow path 111 flows in the direction of the arrow shown in FIG. 1 toward the opposite side of the flow path 111 from the mouthpiece 102.

The CO ₂ concentration measuring device 121 is, for example, NDIR (Non Dispersive Infrared Gas Anaryzer), and measures the CO ₂ concentration in the atmosphere or in the exhaled air flowing through the flow path 111. The CO ₂ concentration measuring device 121 is not limited to a measurement method as long as the CO ₂ concentration in the flow path 111 can be measured.

A path switching unit 125 is provided in a path from the CO ₂ concentration measuring device 121 to the measurement cell 101. The path switching unit 125 is, for example, an electromagnetic valve, and switches the path leading to the CO ₂ concentration measuring device 121 to a path leading to the atmosphere outside the measurement cell 101 or a path leading to the flow path 111 of the measurement cell 101.

  The gas sensor 123 measures the concentration of the specific gas component in the exhalation in the flow path 111. The specific gas component whose concentration is measured by the gas sensor 123 is, for example, carbon monoxide, nitrogen monoxide, hydrogen, alcohols, hydrocarbons such as methane, aldehyde, acetone, isoprene, ammonia and the like.

The control device 150 is connected to the CO ₂ concentration measuring device 121, the gas sensor 123, and the path switching unit 125, and controls the operation of each unit. In addition, the control device 150 controls the display device 170 so that various types of information are displayed on the display unit.

  The power supply 160 supplies power to each unit such as the control device 150 and the display device 170.

  The display device 170 is, for example, a liquid crystal display, and displays various information under the control of the control device 150. The display device 170 displays, for example, the concentration measurement result of the specific gas component in the end-expired air measured by the gas sensor 123.

Note that the configuration of the end-tidal measurement device 11 is not limited to the configuration exemplified in this embodiment. For example, the arrangement of the CO ₂ concentration measuring device 121, the gas sensor 123, and the like in the measurement cell 101 may be different from the present embodiment. Moreover, a filter or the like for dehumidifying the exhaled breath may be provided in the flow path 111 through which the exhaled breath exhaled from the subject 200 flows.

<Functional configuration of control device>
Next, functions of the control device 150 will be described. FIG. 2 is a diagram illustrating a functional configuration of the control device 150 according to the first embodiment.

  As illustrated in FIG. 2, the control device 150 includes a measurement unit 151, a drive unit 152, a concentration calculation unit 153, a measurement value storage unit 154, and a display control unit 155. The control device 150 includes, for example, a CPU, a ROM, a RAM, and the like, and the functions of the respective units are realized by the CPU executing a program stored in the ROM in cooperation with the RAM. Each functional block may be realized by a plurality of circuits.

The measuring unit 151 obtains a measured value of CO ₂ concentration in expired air or air from the CO ₂ concentration measuring device 121. The measurement unit 151 controls the path switching unit 125 to switch the measurement target of the CO ₂ concentration measuring device 121 to the atmosphere or exhalation. The measuring unit 151 controls the driving unit 152 to drive the gas sensor 123 to acquire the concentration of the specific gas component in the end exhalation calculated by the concentration calculating unit 153. In addition, the measurement unit 151 transmits the CO ₂ concentration in the exhaled breath flowing through the flow path 111, the concentration of the specific gas component in the end exhalation, and the like to the display control unit 155 to display on the display device 170.

  The drive unit 152 drives the gas sensor 123 when executing the concentration measurement of the specific gas component in the end expiration. The concentration calculation unit 153 calculates the concentration of the specific gas component in the end exhalation and transmits the calculated concentration to the measurement unit 151.

Measured value storage unit 154 stores the concentration of a specific gas components measured by the CO ₂ concentration and gas sensor 123 measured by the CO ₂ concentration measuring device 121.

The display control unit 155 controls the display unit 171 of the display device 170 to display the CO ₂ concentration transmitted from the measurement unit 151, the concentration of the specific gas component in the end expiration, and the like.

<Gas sensor>
Next, the configuration of the gas sensor 123 will be described. The gas sensor 123 in the present embodiment is a semiconductor gas sensor, and the concentration of the specific gas component is determined based on the resistance value of the gas sensing layer that changes due to the reaction that occurs with the adsorbed specific gas component.

  FIG. 3 is a cross-sectional view illustrating the gas sensor 123 according to the first embodiment.

  As shown in FIG. 3, the gas sensor 123 includes a silicon substrate 2, a thermal insulation layer 3, a heater layer 4, an electrical insulation layer 5, and a gas detection unit 6. In FIG. 3, the shape and film thickness of each layer are shown enlarged or reduced for explanation.

  In the silicon substrate 2, a through hole 2 a penetrating vertically in FIG. 3 is formed in a portion where the gas detection unit 6 is formed.

The thermal insulating layer 3 is formed on the upper surface of the silicon substrate 2 so as to block the upper opening of the through hole 2a and form a diaphragm structure. The thermal insulating layer 3 has a three-layer structure in which a thermally oxidized SiO ₂ layer 3a, a CVD-Si ₃ N ₄ layer 3b, and a CVD-SiO ₂ layer 3c are stacked in this order from the silicon substrate 2 side.

The thermally oxidized SiO ₂ layer 3 a has a small heat capacity, and reduces the amount of heat transferred from the heater layer 4 to the silicon substrate 2. The thermally oxidized SiO ₂ layer 3a is highly resistant to plasma etching. For this reason, the through hole 2a can be formed in the silicon substrate 2 with high dimensional accuracy by plasma etching.

The CVD-Si ₃ N ₄ layer 3b is laminated on the side opposite to the silicon substrate 2 of the thermally oxidized SiO ₂ layer 3a. The CVD-SiO ₂ layer 3c is formed in order to improve adhesion with the heater layer 4 and to ensure electrical insulation.

  The heater layer 4 is, for example, a thin film Pt—W film, and is formed on the upper surface of the thermal insulating layer 3. In the heater layer 4, a wiring layer (not shown in FIG. 3) is formed at the side end, and is connected to the control device 150 through the wiring layer.

The electrical insulating layer 5 is formed so as to cover the heat insulating layer 3 and the heater layer 4. The electrical insulating layer 5 is, for example, a sputtered layer of SiO ₂ and electrically insulates between the heater layer 4 and the gas detection unit 6.

  The gas detection unit 6 includes a sensing layer electrode 7, a gas sensing layer 8, and an adsorption layer 10.

  The sensing layer electrode 7 is formed on the upper surface of the electrical insulating layer 5 and connected to the control device 150. The sensing layer electrode 7 is, for example, a Pt film or an Au film.

The gas sensing layer 8 is formed on the upper surface of the electrical insulating layer 5 so that at least a part thereof overlaps the sensing layer electrode 7. The gas sensing layer 8 is, for example, a SnO ₂ layer. The gas sensing layer 8 may be formed using a metal oxide such as In ₂ O ₃ , WO ₃ , ZnO, or TiO ₂ as a main component.

The adsorption layer 10 is formed so as to cover the entire surface of the gas sensing layer 8. Alternatively, the adsorption layer 10 may have the same size as the gas sensing layer 8 and may be formed on the upper surface of the gas sensing layer 8. The adsorption layer 10 is, for example, a porous layer in which a large number of porous materials (porous particles) are deposited, and a binder resin may be interposed between the porous materials. The adsorption layer 10 is formed, for example, using at least one metal oxide as a main component among Al ₂ O ₃ , Cr ₂ O ₃ , Fe ₂ O ₃ , Ni ₂ O ₃ , ZrO ₂ , and SiO ₂ . For example, the adsorption layer 10 changes the average pore diameter, the average particle diameter, the specific surface area, the polarity, the film thickness, the material, etc., thereby controlling the adsorptivity according to the type of the specific gas component to be measured. Measurement accuracy can be increased.

  Note that the configuration of the gas sensor 123 is not limited to the configuration illustrated in the present embodiment. For example, a diffusion layer for diffusing a specific gas component adsorbed on the adsorption layer 10 may be provided between the gas sensing layer 8 and the adsorption layer 10. The diffusion layer is, for example, a porous layer in which a large number of porous materials (porous particles) are deposited, and a binder resin may be interposed between the porous materials. According to such a diffusion layer, for example, by changing the average pore diameter, average particle diameter, specific surface area, polarity, film thickness, material, etc., the diffusivity can be controlled according to the type of the specific gas component to be measured. The measurement accuracy of the specific gas component can be increased.

  An oxygen supply layer may be formed on the surface of the gas sensing layer 8 (between the gas sensing layer 8 and the adsorption layer 10). By forming the oxygen supply layer and supplying oxygen to the surface of the gas sensing layer 8, the reaction sensitivity between the gas sensing layer 8 and the specific gas component can be improved. The oxygen supply layer is, for example, a metal oxide layer containing a dopant, and is formed on the surface of the gas sensing layer 8 as a metal-supported catalyst layer.

<Concentration measurement of specific gas components>
Next, the principle of measuring the concentration of a specific gas component using the gas sensor 123 in the embodiment will be described.

  First, a specific gas component existing around the gas sensor 123 is adsorbed on the adsorption layer 10 and concentrated. Here, the adsorption of the specific gas component to the adsorption layer 10 occurs while the driving of the heater layer 4 is stopped, and the adsorbed specific gas component is held in a state concentrated in the adsorption layer 10.

  Next, the heater layer 4 is driven by the drive unit 152 of the control device 150, and the adsorption layer 10 is heated. When heated by the heater layer 4, the specific gas component adsorbed and held on the adsorption layer 10 causes thermal desorption in a short time. The specific gas component thermally desorbed from the adsorption layer 10 is adsorbed on the surface of the gas sensing layer 8.

  When the specific gas component is adsorbed on the gas sensing layer 8, a reaction occurs between the specific gas component and oxygen on the surface of the gas sensing layer 8, and the resistance value of the gas sensing layer 8 changes. Here, the concentration calculation unit 153 of the control device 150 obtains the resistance value of the gas sensing layer 8 from, for example, the voltage applied to the sensing layer electrode 7 and the current detection value in the gas sensing layer 8. Further, the concentration calculation unit 153 obtains the concentration of the specific gas component based on the relationship between the resistance value of the gas sensing layer 8 and the concentration of the specific gas component stored in advance in a memory or the like.

  In the gas sensor 123 according to the present embodiment, the driving unit 152 intermittently drives the heater layer 4 so that the specific gas component is thermally desorbed and diffused in a short time after the specific gas component is adsorbed and concentrated on the adsorption layer 10. be able to. Therefore, since the detection sensitivity can be improved by increasing the concentration of the trace gas, the concentration of the trace specific gas component contained in the end exhalation can be measured with high accuracy. Further, the gas sensor 123 according to the present embodiment can instantaneously switch between adsorption / concentration of a specific gas component and thermal desorption / diffusion of the specific gas component, thereby improving the responsiveness.

  In the end breath measurement apparatus 11 in the present embodiment, the gas sensor 123 described above is provided as a gas concentration measuring device. However, if the concentration of a specific gas component in the end breath can be measured, a sensor having a different configuration or method is used. Etc. may be provided.

<End-tidal measurement process>
Next, end breath measurement processing in the end breath measuring apparatus 11 will be described. FIG. 4 is a diagram illustrating a flowchart of end breath measurement processing in the first embodiment.

In the end breath measurement process in the present embodiment, the CO ₂ concentration measuring device 121 is first calibrated in step S101. Calibration of the CO ₂ concentration measuring device 121, the measured value of the CO ₂ concentration in the atmosphere due to the CO ₂ concentration measuring device 121 is performed by adjusting to zero. Measuring section 151 switches the path by controlling the path switching unit 125, during calibration by measuring the CO ₂ concentration in the atmosphere to the CO ₂ concentration measuring device 121, CO ₂ flow path 111 after the calibration measurement cell 101 Allow the concentration to be measured.

  Next, in step S102, end breath measurement is started. The subject 200, for example, presses a measurement start button provided in the end-tidal measurement device 11, and then exhales the breath from the mouthpiece 102 to the flow path 111 of the measurement cell 101.

When measurement of end expiration is started, the CO ₂ concentration measuring device 121 measures the CO ₂ concentration in the expiration in step S103. In step S104, the gas sensor 123 measures the concentration of the specific gas component in the expiration. In the measurement of the specific gas concentration, the drive unit 152 of the control device 150 drives the heater layer 4 of the gas sensor 123, and the concentration calculation unit 153 calculates the concentration of the specific gas component based on the change in the resistance value of the gas sensing layer 8. Is executed.

Measurement of the specific gas component concentration by the CO ₂ concentration of the measurement and the gas sensor 123 according to the CO ₂ concentration measuring device 121, the end tidal measurement end: is performed in (step S105 YES) predetermined period to (e.g., 100 msec). The concentration of a specific gas components measured by the CO ₂ concentration and gas sensor 123 measured by the CO ₂ concentration measuring device 121 is stored together with measurement time to the measurement value storage unit 154.

  After exhaling exhaled breath into the measurement cell 101, the subject 200 ends the measurement in the end exhalation measuring device by, for example, pressing a measurement end button provided in the end exhalation measuring device 11.

In addition, a flow meter may be provided in the flow path 111 of the measurement cell 101, and the start and end of expiration measurement may be determined based on the expiration flow measured by the flow meter. For example, if the exhaled air flow measured by a flow meter is greater than or equal to a predetermined value, end exhalation measurement is started to measure the CO ₂ concentration and specific gas component concentration in the exhaled air, and the exhaled air flow is less than the predetermined value The end breath measurement may be terminated when

Next, in step S106, the measurement unit 151 determines whether or not the CO ₂ concentration measurement result stored in the measurement value storage unit 154 satisfies the concentration measurement condition of the specific gas component.

Here, dead space exhalation that is not used for gas exchange in the alveoli has a low CO ₂ concentration because the gas is not exchanged. Further, the end exhalation used for gas exchange in the alveoli has a high CO ₂ concentration due to the gas exchange. Therefore, it is possible to determine whether the exhaled breath exhaled from the subject 200 is dead-space exhalation or end exhalation based on the change in the CO ₂ concentration in the exhalation.

In the present embodiment, the measured value of CO ₂ concentration in exhaled gas transitions to a threshold value (4%) or more and reaches zero within the second predetermined time (0.5 seconds) after the first predetermined time (2 seconds) has elapsed. When it becomes, it determines with satisfy | filling the density | concentration measurement conditions of a specific gas component.

FIG. 5 is a diagram illustrating the results of measuring the CO ₂ concentration and the concentration of acetone as the specific gas component.

In the measurement result shown in FIG. 5, the CO ₂ concentration increases from the start of measurement and exceeds 4% after about 3 seconds. In addition, after about 2 seconds have passed since the CO ₂ concentration has exceeded 4%, the exhalation of the subject 200 has been switched to inspiration, so that the CO ₂ concentration has rapidly decreased to 4% or more. Within about 0.5 seconds.

In this way, when the state in which the CO ₂ concentration exceeds the threshold and becomes substantially constant continues for the first predetermined time or more and then suddenly changes to zero, the expiration immediately before the CO ₂ concentration decreases is determined as the end expiration. To do. Note that the CO ₂ concentration threshold and each predetermined time described above are not limited to the values exemplified in the present embodiment, and can be set as appropriate. For example, a subject whose exhalation does not last for a long time or a subject whose lung function is impaired is difficult to satisfy the above-mentioned conditions for the CO ₂ concentration threshold and each predetermined time. To change.

When the CO ₂ concentration measurement result satisfies the specific gas component concentration measurement condition (step S106: YES), in step S107, the measurement unit 151 obtains the concentration measurement value of the specific gas component from the measurement value storage unit 154. get. In the present embodiment, the measurement unit 151 acquires the maximum value of the concentration of the specific gas component while the CO ₂ concentration is transitioning above the threshold as described above. In the measurement result shown in FIG. 5, the measurement unit 151 has a maximum value of 0.53 ppb of the acetone concentration between about 3.1 seconds and about 5.5 seconds where the CO ₂ concentration is 4% or more, for example. Obtained as the concentration of a specific gas component in end-expiration.

The measurement unit 151, density measurement and the specific gas component immediately before the CO ₂ concentration is changed to zero from above the threshold, the average value of the plurality of measurements immediately before the CO ₂ concentration is changed to zero from above threshold The concentration of the specific gas component may be acquired.

  Next, in step S108, the measurement unit 151 transmits the concentration of the specific gas component acquired to the display control unit 155, and causes the display unit 171 of the display device 170 to display the concentration of the specific gas component.

If the CO ₂ concentration measurement result does not satisfy the concentration measurement condition for the specific gas component (step S106: NO), the measurement unit 151 causes the display control unit 155 to display the display unit of the display device 170 in step S109. 171 displays that a measurement error has occurred.

For example, if the CO ₂ concentration does not exceed the threshold, or if the CO ₂ concentration does not continue for the first predetermined time or more even if the CO ₂ concentration exceeds the threshold, the concentration measurement result of the specific gas component is displayed as a measurement error. The process ends without

  The end breath measurement apparatus 11 in the first embodiment measures the concentration of a specific gas component contained in end breath exhaled from the subject 200 by the end breath measurement process described above.

As described above, the end-tidal measurement device 11 according to the first embodiment discharges end-tidal when the CO ₂ concentration in the exhalation of the subject 200 satisfies the specific gas concentration measurement conditions described above. The concentration of the specific gas component in the end exhalation is acquired. Therefore, it is possible to measure the concentration of the specific gas component in the terminal exhalation with high accuracy without erroneously detecting the concentration of the specific gas component in the dead space exhalation of the subject 200.

[Second Embodiment]
Next, a second embodiment will be described based on the drawings. Note that a description of the same components as those of the above-described embodiment will be omitted.

<End-tidal measurement device>
FIG. 6 is a diagram illustrating a schematic configuration of the end-tidal measurement device 12 according to the second embodiment. The end breath measurement apparatus 12 in the present embodiment measures the concentration of a specific gas component in the end breath exhaled from the subject 200.

  As shown in FIG. 6, the end-tidal measurement device 12 includes a measurement cell 101, a control device 150, a power source 160, and a display device 170.

  The measurement cell 101 has a first channel 111 and a second channel 112 inside. The first flow path 111 and the second flow path 112 are separated from each other by a partition wall. In the first flow path 111, exhaled air exhaled from the subject 200 circulates. The second flow path 112 has an opening that leads to the outside of the measurement cell 101, and the atmosphere around the measurement cell 101 circulates.

The first flow path 111 is provided with a mouthpiece 102, a CO ₂ concentration measuring device 121, a gas sensor 123 as a gas concentration measuring device, a flow meter 124, a first opening / closing portion 131, and a second opening / closing portion 132. The second flow path 112 is provided with an atmospheric CO ₂ concentration measuring device 122.

  The mouthpiece 102 is provided at the end of the first flow path 111, and guides exhaled air from the subject 200 to the first flow path 111. The exhaled air exhaled from the mouthpiece 102 to the first flow path 111 by the subject 200 flows in the direction of the arrow shown in FIG. 6 toward the opposite side of the first flow path 111 from the mouthpiece 102.

The CO ₂ concentration measuring device 121 is provided in the first flow path 111 and measures the CO ₂ concentration in exhaled air flowing through the first flow path 111.

The atmospheric CO ₂ concentration measuring device 122 is, for example, NDIR, and measures the atmospheric CO ₂ concentration flowing through the second flow path 112 opened to the outside of the measurement cell 101. The measurement method of the atmospheric CO ₂ concentration measuring device 122 is not limited as long as the CO ₂ concentration in the second flow path 112 can be measured. However, in order to perform the comparisons, the CO ₂ concentration measurement result by the CO ₂ concentration measuring device 121, the measurement method of atmospheric CO ₂ concentration measuring device 122 be the same measurement method as the CO ₂ concentration measuring device 121 preferable.

  The gas sensor 123 measures the concentration of the specific gas component in the end exhalation in the first flow path 111.

  The flow meter 124 measures the flow rate of exhaled air flowing through the first flow path 111. As long as the flow meter 124 can measure the flow rate of the exhaled air flowing through the first flow path 111, the measurement method is not limited.

  The first opening / closing part 131 and the second opening / closing part 132 are, for example, shutters that open and close, and each open and close the first flow path 111 according to an opening / closing signal transmitted from the control device 150. The first opening / closing part 131 is provided on the upstream side of the gas sensor 123 in the flow direction of expiration. Further, the second opening / closing part 132 is provided on the downstream side of the gas sensor 123 in the flow direction of the expiration. The first opening / closing part 131 and the second opening / closing part 132 open or close, respectively, to open or shut off the flow of exhalation in the measurement region including the gas sensor 123.

  Note that the first opening / closing part 131 and the second opening / closing part 132 are not limited to shutters as long as the circulation of exhalation in the first flow path 111 can be opened or blocked. The first opening / closing unit 131 and the second opening / closing unit 132 may be, for example, electromagnetic valves that open and close in response to an opening / closing signal transmitted from the control device 150.

The control device 150 is connected to the CO ₂ concentration measuring device 121, the atmospheric CO ₂ concentration measuring device 122, the gas sensor 123, the flow meter 124, the first opening / closing unit 131, and the second opening / closing unit 132, and controls the operation of each unit. . In addition, the control device 150 controls the display device 170 so that various types of information are displayed on the display unit.

  The power supply 160 supplies power to each unit such as the control device 150 and the display device 170. The display device 170 is, for example, a liquid crystal display, and displays various information under the control of the control device 150.

Note that the configuration of the end-tidal measurement device 12 is not limited to the configuration exemplified in this embodiment. For example, the arrangement of the CO ₂ concentration measuring device 121, the gas sensor 123, the flow meter 124, and the like in the measurement cell 101 may be different from the present embodiment. In addition, a filter or the like for dehumidifying the exhaled breath may be provided in the first flow path 111 through which the exhaled breath exhaled from the subject 200 flows.

<Functional configuration of control device>
Next, functions of the control device 150 will be described. FIG. 7 is a diagram illustrating a functional configuration of the control device 150 according to the second embodiment.

  As illustrated in FIG. 7, the control device 150 includes a measurement unit 151, a drive unit 152, a concentration calculation unit 153, a measurement value storage unit 154, and a display control unit 155.

The measurement unit 151 acquires measurement values from the CO ₂ concentration measuring device 121, the atmospheric CO ₂ concentration measuring device 122, and the flow meter 124. Further, the measurement unit 151 transmits an open / close signal to open / close the first open / close unit 131 and the second open / close unit 132 based on the CO ₂ concentration in the expiration measured by the CO ₂ concentration measuring device 121.

The measuring unit 151 controls the driving unit 152 to drive the gas sensor 123 to acquire the concentration of the specific gas component in the end exhalation calculated by the concentration calculating unit 153. In addition, the measurement unit 151 transmits the CO ₂ concentration in the first flow path 111, the concentration of the specific gas component in the end expiration, and the like to the display control unit 155 for display.

  The drive unit 152 drives the gas sensor 123 when executing the concentration measurement of the specific gas component in the end expiration. The concentration calculation unit 153 calculates the concentration of the specific gas component in the end exhalation and transmits the calculated concentration to the measurement unit 151.

Measured value storage unit 154 stores the concentration of a specific gas components measured by the CO ₂ concentration and gas sensor 123 measured by the CO ₂ concentration measuring device 121.

The display control unit 155 controls the display unit 171 of the display device 170 to display the CO ₂ concentration transmitted from the measurement unit 151, the concentration of the specific gas component in the end expiration, and the like.

<End-tidal measurement process>
Next, end expiration measurement processing in the end expiration measurement device 12 will be described. FIG. 8 is a diagram illustrating a flowchart of end-tidal measurement processing in the embodiment.

In the end tidal measurement process in the present embodiment, first in step S201, the CO ₂ concentration measuring device 121 measures the CO ₂ concentration in the first flow path 111. Further, at step S202, atmospheric CO ₂ concentration measuring device 122 measures the CO ₂ concentration in the atmosphere in the second flow path 112. Since the second flow path 112 are open to the outside of the measuring cell 101, the CO ₂ concentration measurements due to atmospheric CO ₂ concentration measuring device 122, the CO ₂ concentration in the atmosphere in the use environment of the end tidal measuring device 12 Show.

Next, in step S203, the measurement unit 151 determines whether or not the measurement start condition is satisfied. For example, the measurement unit 151 determines that the measurement start condition is satisfied when the difference between the measurement values by the CO ₂ concentration measuring device 121 and the atmospheric CO ₂ concentration measuring device 122 is less than a predetermined value.

For example, when the exhaled breath at the previous measurement remains in the first flow path 111, the CO ₂ concentration in the first flow path 111 becomes higher than the CO ₂ concentration in the atmosphere, and the CO ₂ concentration measuring device 121 is covered. There is a possibility that the CO ₂ concentration contained in the exhalation of the examiner 200 cannot be accurately measured. Thus, in the in the end tidal measurement process in this embodiment, until the difference between the CO ₂ concentration in the atmosphere in the CO ₂ concentration and the second flow path 112 in the first flow path 111 is less than the predetermined value, step S204 and subsequent End-tidal measurement is not performed.

  When the measurement start condition is satisfied (step S203: YES), the end breath measurement device 12 is ready for measurement, and the processing after step S204 is executed. Here, for example, guidance such as “please exhale exhaled mouthpiece” or the like may be displayed on the display unit 171 of the display device 170. For example, the subject 200 holds the mouthpiece 102 and exhales according to the guidance displayed on the display unit 171.

  In step S <b> 204, the flow meter 124 measures the flow rate of exhaled air flowing through the first flow path 111. In step S205, the measurement unit 151 compares the flow rate measured by the flow meter 124 with a predetermined value set in advance. If the measured flow rate exceeds the predetermined value (step S205: YES), the process proceeds to step S206.

In step S206, the CO ₂ concentration measuring device 121 measures the CO ₂ concentration of exhaled air flowing through the first flow path 111. Next, in step S207, the measurement unit 151 compares the threshold value set in advance and CO ₂ concentration measured by the CO ₂ concentration measuring device 121.

In this embodiment, when the CO ₂ concentration measured by the CO ₂ concentration measuring device 121 exceeds 4%: (step S207 YES), it is determined that breath discharged from the subject 200 is end tidal Then, the processing after step S208 is executed.

Note that the above-described CO ₂ concentration threshold value is not limited to the value exemplified in the present embodiment, and can be set as appropriate. For example, a subject whose exhalation does not last for a long time or a subject whose lung function is impaired is difficult to satisfy the above-mentioned conditions for the CO ₂ concentration threshold and each predetermined time. To change.

In step S <b> 208, the first opening / closing unit 131 and the second opening / closing unit 132 close the first flow path 111 according to the opening / closing signal transmitted from the measurement unit 151, and block the flow of exhalation in the measurement region including the gas sensor 123. . By blocking the flow of exhalation by the first opening / closing unit 131 and the second opening / closing unit 132, the measurement region including the gas sensor 123 is filled with the end exhalation in which the CO ₂ concentration exceeds the threshold value. In the state where the measurement region is filled with end exhalation in this way, the specific gas concentration in end exhalation is measured by the gas sensor 123 in step S209.

  Next, in step S210, the measurement unit 151 determines whether or not the concentration measurement result of the specific gas component measured by the gas sensor 123 has become constant. For example, the measurement unit 151 determines that the concentration measurement result of the specific gas component has become constant when the measured concentration of the specific gas component has changed within a predetermined range for a predetermined time or more. Moreover, the measurement part 151 acquires the maximum value of the density | concentration of the specific gas component at this time as a measurement result. Note that the measurement unit 151 may acquire an average value of a plurality of measurement results as the concentration of the specific gas component while the concentration measurement result of the specific gas component transitions within a predetermined range.

  If the concentration measurement result of the specific gas component becomes constant (step S210: YES), in step S211, the measurement unit 151 transmits the concentration measurement result of the specific gas component to the display control unit 155, and the display device 170. The display unit 171 displays the concentration of the specific gas component.

  The end breath measurement apparatus 12 in the present embodiment measures the concentration of the specific gas component contained in the end breath exhaled from the subject 200 by the end breath measurement process described above.

For example, if the CO ₂ concentration in the breath of the subject 200 as shown in FIG. 5 was measured, the CO ₂ concentration is breath of the subject 200 is determined to end tidal 4% or more, specific gas component As a result, the concentration of acetone is measured. In the measurement result shown in FIG. 5, the acetone concentration is constant at about 0.53 ppb around 5 seconds when the CO ₂ concentration is changing at 4% or more. The measurement unit 151 acquires the acetone concentration at which the measurement value is constant in the state where the CO ₂ concentration exceeds 4% as a measurement result.

For example, when the concentration of the specific gas component becomes constant regardless of the CO ₂ concentration in the exhalation, if it is determined that the exhalation of the subject 200 is end-expiration, the concentration of the specific gas component may be erroneously detected. . In such a method, for example, as shown in the measurement result shown in FIG. 5, the acetone concentration (approximately 0.19 ppb) that became temporarily constant in the dead space exhalation in about 2.5 seconds was measured at the end expiration. There is a possibility that.

In the end breath measurement apparatus 12 in the second embodiment, when the CO ₂ concentration in the breath exceeds the threshold, it is determined that the breath of the subject 200 is the end breath, and the concentration measurement of the specific gas component is executed. Is done. Therefore, as described above, it is possible to measure the concentration of the specific gas component in the end exhalation with high accuracy without erroneously detecting the concentration of the specific gas component in the dead space exhalation.

The measurement unit 151 may obtain as a result measuring the maximum value of the specific gas component concentration between the CO ₂ concentration measured exceeds the threshold value by the CO ₂ concentration measuring device 121.

As described above, the end-tidal measurement device 12 according to the second embodiment determines that the exhalation of the subject 200 is end-expiration when the CO ₂ concentration in the exhalation of the subject 200 exceeds the threshold value. Determine and execute the concentration measurement of the specific gas component. Therefore, it is possible to accurately measure the concentration of the specific gas component in the terminal breath of the subject 200.

  The end breath measurement device and the end breath measurement method according to the embodiment have been described above. However, the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

8 Gas sensing layer 10 Adsorption layer 11, 12 End breath measurement device 101 Measurement cell 111, 112 Channel 121 CO ₂ concentration measuring device 122 CO ₂ concentration measuring device 123 in the atmosphere 123 Gas sensor (gas concentration measuring device)
124 Flow meter 125 Path switching unit 131, 132 Opening / closing unit 150 Control device 151 Measuring unit 200 Subject

Claims (6)

An end-tidal measurement device that measures the concentration of a specific gas component in end-tidal air,
A measurement cell in which a flow path through which a subject's exhalation flows is formed;
And CO ₂ concentration measuring device for measuring the CO ₂ concentration in the exhaled breath flowing through the flow passage,
A gas concentration measuring device for measuring the concentration of the specific gas component in exhaled air flowing through the flow path;
A measuring unit that obtains a concentration of a specific gas component in the end-expired gas from a measured value of the gas concentration measuring device while the CO ₂ concentration in the exhaled gas is transitioning above a threshold value. End-tidal measuring device. The measuring unit changes the first predetermined time when the CO ₂ concentration in the exhalation changes for a first predetermined time at the threshold value or more and changes to zero within a second predetermined time after the first predetermined time elapses. 2. The end-tidal measurement apparatus according to claim 1, wherein a maximum value of the concentration of the specific gas component in is set as a concentration of the specific gas component in the end-expiration. The measuring unit changes within the predetermined range when the concentration of the specific gas component changes within a predetermined range and a predetermined time or more elapses while the CO ₂ concentration in the exhalation is equal to or higher than the threshold. 2. The terminal expiration measurement apparatus according to claim 1, wherein the maximum value of the concentration of the specific gas component is the concentration of the specific gas component in the end expiration. The terminal breath measurement apparatus according to any one of claims 1 to 3, wherein the gas concentration measuring device is a semiconductor gas sensor. The gas concentration measuring instrument is
An adsorption layer for adsorbing the specific gas component;
A gas sensing layer for sensing the specific gas component;
A gas detector having a heater layer for heating the gas sensing layer;
A drive unit for driving the heater feed,
5. The terminal breath measurement apparatus according to claim 4, wherein the concentration of the specific gas component is calculated based on a resistance value of the gas detection layer that changes in response to the specific gas component in the gas detection layer. An end expiration measurement method for measuring the concentration of a specific gas component in end expiration,
And CO ₂ concentration measurement step of measuring the CO ₂ concentration in the exhaled breath flowing through the flow path of the measurement cell,
A gas concentration measuring step for measuring the concentration of the specific gas component in exhaled air flowing through the flow path;
Measuring the concentration of the specific gas component in the end exhalation from the concentration of the specific gas component while the CO ₂ concentration in the exhalation transitions above a threshold value. Measuring method.

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