JPH019531Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a mechanical spirometer (respirometer) that measures the amount of respiratory air by making one end of the container into which breathing air is introduced movable, and measuring the amount of breathing air from the amount of displacement of that end. ).

In general, in pulmonary function tests using a spirometer, the temporal vital capacity rate (for example, the 1-second rate), which is the ratio of forced vital capacity to the temporal vital capacity measured from the start of exhalation, determines the quality of lung function. This is an important indicator. Such measurements can also be performed by using a pneumotachograph and integrating the differential pressure signal in the fluid resistance tube with an electronic circuit, but since the differential pressure changes depending on the mass of gas, There is a drawback that measurement accuracy decreases if the components such as CO ₂ or anesthetic gas contained are not clear.
Therefore, mechanical spirometers of the type mentioned above, such as the Benedict-Ross type, rolling seal type, or bellows type, are usually used at the cost of being bulky, but the inertia of the moving parts Mass cannot be ignored, and there have been problems in particular with respect to the measurement accuracy of the above-mentioned temporal vital capacity rate, which measures regions where respiratory volume rapidly changes. This drawback is due to
53-41920, an improvement was made by adding a servo control device that detects the internal pressure of the container and moves the end of the container so that the internal pressure becomes atmospheric pressure, but compensation for such a response delay at the end of the container is There was a limit due to the follow-up delay peculiar to servo systems.

Therefore, an object of the present invention is to provide a spirometer that can measure respiratory air volume with higher accuracy even when the respiratory volume changes rapidly.

Next, the present invention will be explained based on the illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a cylindrical container into which breathing air is introduced through a flexible pipe 2, and an end 4 of the container 1 on the opposite side to the breathing air introduction side is provided with a rolling seal 3 depending on the breathing air volume. It is configured to be movable. Reference numeral 5 denotes a rod that is fixed to the end 4 and guides the movement of the end 4 along the bearing 6. 10 is a displacement sensor that detects the displacement of the rod 5 in order to detect the respiratory air volume, that is, the displacement of the end portion 4; and 11 is a pressure sensor that detects the internal pressure of the container 1. 12 and 13 are both sensors 10, 1
An amplifier that amplifies each of the detection signals of 1,
Among these, the gain of the amplifier 13 can be adjusted by a variable resistor 14. Reference numeral 15 denotes an adding circuit that adds the amplified outputs of both amplifiers 12 and 13 and outputs a respiratory volume signal that enables measurement of ventilation volume, vital capacity, etc.

Next, the operation will be explained with reference to FIG.

For example, in order to measure the hourly vital capacity rate, when a subject holds the flexible pipe 2 in their mouth and begins maximal forced exhalation, exhaled air is rapidly introduced into the container 1. As a result, the end portion 4 tries to move outward, but the response is delayed due to the inertial mass of itself or the rod 5, the rolling seal 3, etc., and the output signal a of the displacement sensor 10 is also affected by the rapid increase in expiratory volume. Regardless, it will rise slowly. Corresponding to this delay in the response of the end portion 4 to exhalation, the internal pressure of the container 1 rises from atmospheric pressure, and therefore the output signal b of the pressure sensor 11 rises rapidly with the start of exhalation, and the end portion 4 It rapidly decreases as you move, following gradual changes in expiratory volume. These output signals a, b
are amplified by amplifiers 12 and 13, respectively, and the signal
a' and b', which are added in the adder circuit 15. As a result, a respiratory volume signal c that accurately corresponds to the forced vital capacity compensated for the response delay at the start of exhalation.
is generated. That is, since the level of the output signal b' is adjusted in advance by the variable resistor 14 to correspond to the response delay of the end portion 4, the respiratory volume signal c accurately follows the forced vital capacity from the beginning of expiration. do. Therefore, by supplying this respiratory volume signal c to, for example, a recorder, a forced vital capacity curve can be accurately drawn, and the hourly vital capacity rate, for example, the rate per second, can be measured with high accuracy.

Note that the amplifier 13 can be set to an optimal fixed gain, and in some cases, the level-adjusted outputs of both sensors can be added and then amplified. In addition, in the above embodiment, both sensors were explained as outputting DC signals corresponding to pressure and respiratory volume, but when the displacement sensor and pressure sensor are implemented as differential transformer type, the output waveform is Each of the waveforms a' to c in FIG. 2 becomes a modulated waveform whose envelope is a waveform that appears symmetrically on both sides. for example,
When the inputs of these differential transformers are commonly connected to a commercial power source, the input ends of the adder circuit shown in FIG. 1 are made to have the same phase, and the phase is finely adjusted if necessary. Furthermore, the present invention can be applied to a Spiro with containers of various structures, such as a bell-shaped container or a Benedict-Ross type, in which a bell-shaped container is placed upside down in a water-filled container and suspended by a counterweight via rollers. It is also applicable to meters.

As described above, according to the present invention, by performing open-loop compensation in which the container internal pressure signal is added to the displacement amount signal of the moving part to compensate for the measurement error of respiratory air volume caused by the response delay of the moving part of the container, it is possible to easily It becomes possible to measure respiratory volume, which is accompanied by rapid changes, including vital capacity rate, with high precision.

[Brief explanation of the drawing]

FIG. 1 shows a spirometer according to the invention (the container is shown in cross-section) and FIG. 2 shows waveforms of its electronic circuitry. 1... Container, 4... End, 10... Displacement sensor, 11... Pressure sensor.

Claims (1)

[Scope of utility model registration request] A container having a moving end into which breathing air of a subject is introduced, a pressure sensor that detects the pressure within the container, a displacement sensor that detects movement of the end, and both of the sensors. A spirometer characterized by having an addition circuit that adds output signals.