DE2057638C3 - Device for determining the breath value as well as for measuring ventilation variables - Google Patents

Description

The invention relates to a device for determining the breath value and for measuring ventilation variables such as momentary breath flows or tidal volumes, which is provided with a flow resistance that converts the momentary breath flow into a proportional, to avoid negative repercussions on the measured object, only a few mm WS high pressure drop converts

As is well known, the examination of the respiratory tract is carried out by means of a recorded expiration curve, which is used as the significant measure of the »usable portion of the maximum tidal volume «is characterized by that part of the maximum tidal volume, which after deep inspiration the person can exhale as quickly as possible in the first second. The so-called "Tiffeneau test" through the breathing test The determined maximum breath-second volume corresponds to the breath value and is absolute in ml or relative as a percentage of the maximum tidal volume. The absolute values of the breath pressure * However, tes are not only dependent on factors such as B. the expiratory force, depending on which the maximum Tidal volumes change, but their size depends largely on the quality of the equipment used

influenced

The for determining the breath value or for Devices known to measure ventilation variables exist as a transducer in addition to the flow resistance from electrical components or from mechanical devices with the function of Amplifiers and integrators to obtain the output variables. Your pneumatic input variable an electrical or other physical quantity such as path, Converted angles and the like (DD-WP 52 530). But at the same time this prevents one of the to deliver a pneumatic output signal corresponding to the measured ventilation variable, for example would be necessary to influence a ventilator. In addition, the evaluation of the Measurement results, especially when determining the breath value, a recorded expiration curve presupposes and consequently the known devices must be partially coupled with a writing instrument. These technically and economically complex facilities as well as the large amount of time required to evaluate the written curve - the measured value of interest when determining the breath value kanin is not can be read directly - wants another ·! device avoid by placing a pneumatic between the flow resistance and the outlet Amplifier and optionally in between a pneumatic element or a pneumatic integrator or also both are arranged together. In the direction of flow in front of the amplifier there is a shunt at low differential pressure at the flow resistance overridable second amplifier arranged with a switch that closes the flow line in the event of override

If you follow the function of this device, you will see that there is always a dem at the output respective tidal volume proportional pressure is present when the signal is given in the direction of the exit

The pneumatic integrator runs changes the direction of flow of the air resulting in the transition from the exhalation corresponds to the inhalation so the differential pressure at the flow resistance becomes negative. This also results in a negative output signal from the easily overdriven second amplifier, as a result of which the ski holder connected to it is made and the aforementioned integrator is vented. With this one Process, the output signal at the output becomes zero again (DD-WP 80 799).

Apart from the amplifier specially designed for venting, a before Integrator performed venting due to its own time constant the possible measuring range highly limited

The invention aims to eliminate the disadvantages of the known embodiments and to provide a device create that guarantees comprehensive use with the lowest possible technical and economic effort

The invention is based on the object of a device for determining the breath value and for measurement of ventilation sizes without the use of electrical or mechanical links one of the quantities to be measured supplies an output quantity analogous to the quantity to be measured and displays it directly

According to the invention the object is achieved in that a pneumatic one parallel to the integrator Switching gate with an attached pneumatic

Division link is arranged, which in the shunt is connected to a time base circuit, which in turn receives the signal coming from the integrator in supplies the division member in an analogous manner.

This solution according to the invention has the advantage that once the output signal of the flow resistance downstream amplifier is used directly to control the switching gate and, on the other hand, at the integrator output is vented, based on the functional principle of the Hcs Integrator, a safe venting is guaranteed with a relatively large measuring range.

It is advantageous to use the time base circuit with a to provide a second switching gate, which has a pneumatic amplifier with a very large gain factor and a pneumatic AC member in Series connection is controlled.

This makes it possible to read off the actual measured value directly, which is particularly important with the Determination of the breath value saves a great deal of time, and in addition, the previously arising from the complicated evaluation work

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The invention is hereinafter based on a Ji the Drawing illustrated embodiment will be explained in more detail.

As the schematic illustration shows, a pressure signal proportional to the volume flow is picked up at a flow resistance 1 and amplified by a downstream pneumatic amplifier 2 with an adjustable gain factor.This amplified pressure signal x \ corresponds to the instantaneous respiratory flow V and can be displayed on a suitable instrument 11 will. At the same time, the pressure signal x \ is further processed in a pneumatic integrator 3, so that a pressure signal Χϊ proportional to the tidal volume V _T is present at the integrator output, which pressure signal can also be displayed on a suitable instrument 10. The establishment, after each finished breath vent of the integrator 3 is via a ugeordnetes parallel to it pneumatic switching gate 4. This is achieved by the voltage proportional to the flow of breath pressure signal X \ controlled so that switched at the zero crossing, that is, after each completed breath, the pressure signal X2 against atmosphere At the maximum respiratory flow V _m "a maximum tidal volume Vrna " results at the output of the integrator 3, which is used to determine the breath value in two branches connected in parallel, specifically directly to the division term

8 and on the other hand via a time base circuit to the divider 8. The time base circuit consists of a pneumatic switching gate 5, which is controlled via a pneumatic amplifier 6 with a gain factor K, which charges a pneumatic component 7. The time constant of the RC element 7 is chosen so that the switching gate 5 switches over after exactly one second The pressure signal corresponding to the Vrmaz is applied in parallel and the integrator 3 is vented. Both pressure signals xi and X3 are processed in the division element 8, so that at its output a pressure signal x * is applied which corresponds to the quotient

corresponds to and represents the breath value Das

^ T max

Pressure signal x + can either be processed via a p ^r -: p- £ / -Wander 12 ^ and / or on a suitable instrument calibrated to absolute and / or percentage values

9 are displayed.

Reference number:

t flow resistance

2 amplifiers

3 integrator

4 switching gate

5 switching gate

6 amplifiers

7 ÄC member

8 division member

9 instrument

10 instrument

11 instrument

12 p-i / converters

Formula symbols:

V. j
Vr

Breath flow
maximum breath flow
Tidal volume
maximum tidal volume
Tidal volume per second
Breath value

1 sheet of drawings

Claims (6)

Patent claims: 1. Device for determining the breath value as well as for measuring ventilation variables, its flow resistance designed as a measuring transducer via pneumatic components such as amplifiers, Integrator and ßC-member to appropriate measuring instruments and / or p-L / converter connected is, characterized in that a pneumatic switching gate parallel to the integrator (3) (4) is arranged with an adjoining pneumatic division member (8), which is shunted with a time base circuit (6, 7 and 5) in connection, which in turn is that of the integrator (3) the incoming signal is fed to the division element (8) in an analogous manner. 2. Apparatus according to claim 1, characterized in that the time base circuit with a switching gate (5) is provided. its control by means of a series-connected amplifier (6) and ÄC element (7) 3. Apparatus according to claim 1 and 2, characterized in that the division member (8) a dem The measuring device (9) indicating the breath value is connected downstream 4. Apparatus according to claim 1 to 3, characterized in that for the display of the respiratory flow V output side of the amplifier (2) and for the display of the tidal volume Vt the output side of the integrator (3) a measuring instrument (11 and 10) is arranged 5. Device nau.i claim 1 to 4, characterized in that out. "Jigssei ' ^: 2 of the division member (8) and next to drm measuring device (9) a pL / converter (12) is connected 6. Apparatus according to claim 1 to 5, characterized in that the output side of the amplifier (2) acting pressure signal xu directly controls the switching gate (4) intended for venting and the venting takes place at the integrator output