DE1791124A1 - Device for examining lung function - Google Patents

Description

Siemens Aktiengesellschaft Erlangen, November 4, 1969

Henkestrasse 127

Current time P 17 91 124.9 -25 VPA 3Oa4 / 19O St / Na

Device for the study of lung function

The present invention relates to an apparatus for examination the lung function, in particular with: a cabin for whole-body plethysmography with measuring devices for the determination of the chamber pressure fluctuations Pj, (piezo- or mechanical-electrical Converter) and for the determination of the respiratory flow strength "^ Pneumotachograph) while breathing.

In such devices, the _{electrical quantities (voltages) corresponding to the measured quantities P K} and V are fed to a coordinate recorder which records so-called pressure / respiratory flow strength curves, which in a healthy test person essentially have the form shown in FIG pathological - ie medically interesting - cases degenerate into so-called club shape (Fig. 3), club shape (Fig. 4), bubble shape (Fig. 5) or the like. The deviation of pathological curves from the normal form results z. B. from the fact that despite the increase in the respiratory pressure (and thus of Pj,) there is no corresponding increase in the breath current intensity V if there are pathological changes in the test person's airway, ie P _{K increases} with the V remaining the same.

The curves are evaluated in such a way that for determination of the lung resistance value sought in significant points (extreme values of Pj,) auxiliary lines are drawn, the (reciprocal) Steepness is a measure of resistance.

The present invention is based on the knowledge that the pressure / respiratory flow rate curves recorded so far, although the internal

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Interesting information contain that this information can only be obtained from these curves with difficulty, i.e. by specialists with a large expenditure of time, and that a comparison of different curves (e.g. to follow a healing process is only possible if the measuring apparatus is under the same conditions works or if the curves (e.g. with different measuring devices) work with the same recording measures. However, these prerequisites are usually not met Difficult to evaluate pressure / respiratory flow rate curves can be obtained without any effort at the same time the desired information about the lung resistance R and also a further variable is given which represents an objective measure of the deformation of the curves measured up to now current size d pulmonary resistance R /. \ there is an electrical divider, the inputs of which are connected to the measuring devices for the quantities P ^ and V, if necessary via filters and amplifiers. According to a further invention, a phase measuring device is used to determine the instantaneous deviation of the time course of P _K and V during breathing, to whose inputs the measuring devices for the quantities P _K and V, if necessary via filters and amplifiers, are also connected.

The display of the phase angle between the pressure and respiratory flow rate, together with the resistance measurement results, not only provides a measure of the type of deformation of the curves, ie the size of the pulmonary tract obstruction, but also - z. B. depending on the sign, a measure for the type of deformation. Due to the simultaneous indication dieeer sizes the doctor all major removable from P _R and V information is directly and without further Arbeitaauf- · wall accessible. In addition, through the invention of time

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The course of the instantaneous value of the lung resistance is easily recorded; however, the course of the lung resistance value during breathing is particularly informative from a medical point of view, and it has been so far because of the mostly very shaky shape of the curves only approximately, .iu imprecise and after extensive evaluation work to be determined

In this context it should be noted that the invention achieves a further advantage: the migration of the curves due to the heating of the chamber or due to slowly changing ambient conditions, namely according to a further invention by connecting a differentiating element in front of the inputs of the variables P _R and V processing divider can be prevented.

Further advantages and details emerge from the drawing, based on which an exemplary embodiment of the invention in 6 figures is explained. Show it

Fig. 1 shows a cabin for whole-body pletysmography in Cut,

2 shows a pressure / respiratory flow strength curve of a healthy test person,

Fig. 3 * ^ - and 5 of sick test subjects, Figure 6 is a block diagram of the invention. .

In FIG. 1, 1 indicates the cabin, and 2 indicates that it is seated in it and in the pneumotachograph 3 patient breathing and with 4 the in

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the pressure comparison vessel located in the cabin. By means of known and therefore not described pressure sensors, the electrical voltage corresponding to the chamber pressure fluctuations is measured via the lines 5, 6 (P _K )> on the pneumotachograph, the electrical voltage proportional to the respiratory flow strength (V) is taken from the lines 7-8.

In FIG. 6, the input of the _{electrical voltage corresponding to the value P K} is designated with 9 and the input of the electrical voltage corresponding to the value V is designated with IO. 11 and 12 represent filters for the suppression of high-frequency interference, IJ and 14 are amplifiers for the voltages applied to the input. 15 is a phase measuring device and 16 is a display device. The reference numerals 17 and 18 are used for differentiators. The dividing member is 19, the downstream integration member with 20 and the display device for the integrated size with 21 loading. draws. The output 22, 22 '/ is intended for the connection of a recording device «2J. A trigger 24 is connected between the differentiating element 18: and the dividing element I9.

The function of the individual circuit units is as follows

After filtering 11, 12 and amplification Ij5, 14 of the fed Sizes P "and V these are on the one hand the phase measuring device 15 and the display device 16 connected downstream of it and, on the other hand, the two differentiating elements 17 and 18 and the recording device SJ (Entrances 22, 22 ') supplied. Take the two fed-in sizes is not proportional to or from, the phase angle between the lead or lag of the one variable is displayed on the display device 16 the other than one of the 0 position in positive or negative Direction deviating deflection displayed. The display device 16 can enteprediend the integration maintenance

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integrator 20 can be connected upstream or it can itself be designed as an integrating measuring instrument. It is particularly advantageous to additionally provide a circuit for the display device l6, which the between the times \. ⁺ Pr, and * Φ max. Saved phase angle over the remainder of a breathing cycle.

The differentiators 17 and 18 have the effect that only the (relative rapid) changes to the fed-in variables are processed will; on the other hand, the measurement signals superimposed direct current components and slow changes, such as those z. B. by the slow heating (and thus pressure increase) occur in the cabin, suppressed.

_{The variables P K} and V, which vary over time, are fed to the dividing element 19, which uses them to calculate the instantaneous lung resistance value. This calculated value is ^{fed to the output 22 lf} (the recorder 23).

The respiratory flow strength V changes during the transition from inhalation to exhalation and vice versa their direction (their sign). When the current Y = Q crosses zero, the trigger 24 is triggered. This Trigger controls the divider at every second zero crossing 19 anew, so that the integrator connected downstream of the link I9 over a breath cycle (inhalation and exhalation) the calculated Resistance value middle * It, then appears on the display device the mean resistance value of a breathing cycle.

The alveolar pressure need not be obtained in a plethysmograph chamber indirectly via the measurements of P _K ; Instead, the lung pressure of interest can also be measured directly using an esophageal probe and processed in the device according to the invention .

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Claims (8)

Claims 1. Device for the investigation of the lung function, in particular with a cabin for the whole body plethysmography with heating devices for the determination of the chamber pressure _{fluctuations P R} (piezo or mechanical-electrical transducer) and for the determination of the respiratory flow strength V (pneumotachograph) during breathing «characterized in that, for determining the current size of the pulmonary resistance R ^ v an electric dividing element is present "at the inputs of which Heßgeräte for the sizes _Έ ν and V, optionally with filters and encryption. stronger, connected. 2. Apparatus according to claim I _4, characterized in that a recording and / or recording device is connected to the output of the dividing member. ; J3. Device according to claim 2, characterized in that as Display device an integrating measuring instrument is used or an integrator is connected upstream of the display device. 4. Device according to one of claims 1 to 2, characterized in that that an electrical differentiating element is connected upstream of each of the two inputs of the dividing element. 5. Apparatus according to claim 4, characterized in that the the differentiator processing the respiratory flow bags V a trigger downstream to control the dividing element 1st. 6. Device for the investigation of the lung function, in particular with a cabin for the whole-body plethysmograph old measuring devices for the determination of the camera pressure fluctuations P _R - 7 109846/0548 BATH ORIGINAL. (piezo- or mechanical-electrical transducer) and for determining the respiratory flow strength V (pneumotachograph) during breathing, in particular according to one of the preceding claims, da ^
characterized in that a phase measuring device is available to determine the instantaneous deviation of the time course of P _K and V during breathing, to whose inputs the measuring devices for the quantities P _R and V, possibly via filters and amplifiers, are connected. 7.Gerät according to claim 6, characterized in that on
A display and / or recording device is connected to the output of the phase measuring device. 8. Apparatus according to claim 7, characterized in that an integrating measuring instrument is used as the display device. 109846/054