JPS6338435A - Respiration metabolism measuring apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a respiratory metabolic measuring device H for measuring the concentration of oxygen and carbon gases in the exhaled breath of a living body, and particularly relates to a respiratory metabolic measurement device H that measures the concentration of oxygen and carbon gases in the exhaled breath of a living body. Regarding the structure of the mixing chamber.

(Prior Art) Measuring the oxygen and carbon dioxide concentrations in the exhaled breath of a living body, especially a human body, to measure respiratory metabolic performance is an important element in medical diagnosis. The respiratory metabolic measuring device for this purpose consists of a flowmeter that measures the expiratory flow rate, a mixing chamber that eliminates concentration differences in exhaled air and diffuses it uniformly, and an oxygen/carbon dioxide sensor that measures the oxygen and carbon dioxide concentrations in exhaled air. It has become. As shown in Fig. 3, the conventional mixing chamber 1 is formed into a sealed cylindrical shape with pipes 2 and 3 provided on both end faces, and one end of the pipe 2 on the inlet side of these pipes 2゜3. protruded into the mixing chamber 1 and had a large number of holes 2a formed on its outer periphery. Such a mixing chamber 1 has the effect of completely diffusing the exhaled air remaining in the chamber 1 and the newly sent exhaled air, and eliminates the concentration difference of the exhaled air within the chamber 1. However, there are individual differences in expiratory volume, and there is a particularly large difference between at rest and during exercise. On the other hand, since the internal volume of the conventional mixing chamber 1 is constant, for example, if the exhalation port is as small as 300 cc, it will take a long time for complete diffusion, and if it is as large as 1000 cc, the time required for diffusion will be longer. There was a problem that there were few and there was a time difference. For this reason, when trying to measure exhaled breath concentration after completion of diffusion, the time delay is often inconsistent. Additionally, when attempting to automatically calibrate a flowmeter, a bypass must be installed in the pipes before and after the flowmeter, and the calibration must be performed via a separate flow path using a separate calibration device. There was also the problem that it was troublesome.

(Problems to be Solved by the Invention) The present invention has a problem with conventional respiratory metabolic measurement devices because the mixing chamber has a constant internal volume, so a time lag occurs in the diffusion of exhaled air within the chamber, which causes the problem to increase. ! To provide a respiratory metabolism measuring device capable of diffusing exhaled air in a short time and easily calibrating the flow meter, solving the problems that i time may take a long time and calibrating the flow meter is troublesome. With the goal.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a flow meter that measures the expiratory flow rate of a living body, a mixing chamber that diffuses the exhaled air, and a mixing chamber that diffuses the exhaled air. In a respiratory metabolism measuring device that has a sensor that measures gas concentrations such as oxygen and carbon dioxide concentrations,
A partition wall provided in the mixing chamber so as to be slidable in an airtight manner, a driving means for driving the partition wall, and a control device for setting the driving amount of the driving means based on a signal from the flow meter. be.

(Function) According to the above configuration, by applying a signal detected by the flow meter to the driving means, the partition wall can be moved to a position suitable for the exhalation port. As a result, the volume of the portion of the mixing chamber partitioned by the partition wall is automatically set to a volume that matches the preset amount of exhaled air, so that the exhaled air within the mixing chamber is completely diffused in a short period of time. In addition, if the distance between the detection means that detects the moving ends of the partition wall is set in advance to correspond to a constant volume change in the mixing chamber, the flowmeter will By comparing the integrated value, the flow meter can be easily calibrated.

(Example) Below, respiratory metabolism measurement according to the present invention! An embodiment of the device will be described with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

The conduit on the inlet side of the exhaled air to be measured includes a mouthpiece 1° flexible tube 2, a direction converter 3, a bypass switching valve 4, a heater 5 with a thermistor, a differential pressure flowmeter 6, a bypass switching valve 7, a mixing chamber 8, Flexible tube 9, switching valve 10, piping 11
are connected in sequence. An oxygen/charcoal gas sensor 13 is connected to the downstream side of this piping 11 via a cooler 12 with a fan and a thermistor, and a pump 14 is provided approximately downstream thereof. 15.16 are zero gas and span gas cylinders for calibration, each equipped with a valve 17°18 and a flow meter 19.20;
It is connected to the inlet side of the cooler 12 via the switching valve 21@.

The mixing chamber 8 is connected to the bypass switching valve 7 by a pipe 22, and one end of the pipe 22 protruding into the chamber 8 has an enlarged diameter and a sealed end surface. A large number of holes 22 are provided on the outer circumferential surface of this enlarged diameter portion 22a.
b is formed. A partition wall 24 is airtightly and slidably provided on the inner peripheral surface of the chamber 8 via a 7-shaped seal rubber 23, and a V-shaped seal rubber 25 is provided on the exit side end surface of the chamber 8 to this partition wall 24. One end of the vibrator 26, which is airtightly and slidably attached to the vibrator 26, is opened and fixed.

A rank 27 is fixed in parallel to the axial direction on the outer peripheral surface of a portion of the vibrator 26 that protrudes from the chamber 8, and a pinion gear 29 driven by a motor 28 meshes with the rack 27. Further, a limit switch 31 is attached to the main body frame 30 at the bottom of the via 26.
32 and a potentiometer 33 are provided. 34 is a control device, and a calculation circuit 35 converts the expiratory flow rate signal sent from the flow meter 6 into an expiratory volume, that is, a ventilation volume.
The exhalation set signal outputted from the calculation circuit 35 and the position signal of the partition wall 24 sent from the potentiometer 33 are received and compared, and the expiration volume set and stored in advance is determined.
It is comprised of a comparison circuit 36 that sets the partition wall movement port based on a position curve, and a drive circuit 37 that drives a motor based on commands and command signals output from the comparison circuit 36.

Next, the operation of this embodiment will be explained. The exhaled breath of the person to be measured is sent from any direction to the heater 5 via the mouthpiece 1, the flexible tube 2, and the direction changer 3, and is heated to an appropriate temperature to prevent dew condensation. At this time, the bypass switching valves 4 and 7 are set in the straight direction.

Then, it passes through the flow meter 6 and enters the exhalation flow port (unit, !!/S)
is measured and sent into the mixing chamber 8.

Here, the exhaled air is ejected from the hole 22b formed in the enlarged diameter portion 22a, and the exhaled air remaining in the space between the inlet side end face of the chamber 8 and the partition wall 24 is combined with the newly introduced exhaled air. are mixed and completely diffused without any concentration difference. This diffused exhaled air is introduced into the cooler 12 through the pipe 26, valve 101, and piping 11, and after being cooled to an appropriate temperature, the concentration of hydrogen and carbon dioxide in the exhaled air is measured by the oxygen/carbon dioxide sensor 13. and is discharged into the atmosphere by the pump 14.

Here, the relationship between the content opening of the chamber 8 and the amount of exhaled air, which allows exhaled air to be efficiently diffused in the chamber 8 in a short time, is as shown in Table 1 below, for example.

The internal volume between the inlet side end face of the first chamber 8 and the partition wall 24 is detected by a potentiometer 33 via a pipe 26 fixed to the partition wall 24 . If the relationship between this internal volume and the exhaled air measured by the flow meter 6 deviates from the relationship shown in Table 1, the comparison circuit 36 commands the motor 28 to be driven in a direction that brings this relationship into agreement. is output to the drive circuit 37, and the motor 28 rotates to move the via 268 in the axial direction via the pinion gear 29 and the rack 27 until the partition wall 24 reaches a position where it has an appropriate internal volume and stops. That is, the mixing chamber 8 can always be maintained at an internal volume that matches the expiratory volume measured by the flow meter 6. Therefore, exhaled air within the chamber 8 can be completely diffused in a short time.

Next, a method of calibrating the flow meter 6 will be explained. The interval between the limit switches 31 and 32 is set in advance at a position g2 where the change in internal volume due to movement of the partition wall 24 in the chamber 8 is a constant value. Then, close the valve 10 and
By sending fluid such as exhaled air to the body and moving the partition 24,
A dog (not shown) provided at 26 is a limit switch 31
Calibration is performed by comparing the cumulative volume of fluid that passed through the flow meter 6 between hitting the limit switch 32 and hitting the limit switch 32 with the set change in the internal volume of the chamber 8.

According to the method of calibrating the flowmeter 6 according to this embodiment, there is no need to form a bypass using the switching valves 4 and 7 and calibrate using a separate calibration scheme as in the conventional method, and even during exhalation measurement using the mixing chamber 8. Calibration can be easily performed.

In this example, flow! Although the case where the meter is a differential pressure type flowmeter has been described, it goes without saying that this flowmeter is not limited to a differential pressure type.

Note that if means such as a pulse motor whose displacement a is accurately proportional to the input signal is used as the partition wall driving device, the potentiometer 33 as the position detecting means can be omitted.

[Effects of the Invention] As described above, according to the present invention, the internal volume of the mixing chamber provided in the respiratory metabolism measuring device is changed in accordance with the amount of inhaled air, so that the diffusion S of exhaled air within the chamber is: This can be done in a short time, and the flowmeter can be easily calibrated.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the respiratory metabolism measuring device according to the present invention, FIG. 2 is a longitudinal sectional view showing the mixing chamber of FIG. 1, and FIG. 3 is a longitudinal sectional view showing a conventional mixing chamber. It is. 6... Flow chamber meter 8... Mixing chamber 13... Sensor 24... Partition wall 28.
...Motor (driving means) 31, 32...Limit switch (moving end detection means)
33... Potentiometer (position detection means) 34...
·Control device.

Claims (1)

[Claims] In a respiration metabolism measuring device having a flow meter for measuring the flow rate of exhaled air of a living body, a mixing chamber for diffusing the exhaled air, and a sensor for measuring the gas concentration in the exhaled air, the air-tight air-tight sliding mechanism is provided in the mixing chamber. 1. A respiration metabolism measuring device, comprising: a partition wall having a partition wall, a driving means for driving the partition wall, and a control device for setting a driving amount of the driving means based on a signal from the flow meter.