DE2719900A1 - RESPIRATION ANALYZER - Google Patents

Abstract

The respiration analysis instrument comprises a measuring head (1) for the flow of respiratory gas. This measuring head comprises a flow tube which delimits a single flow channel and whose one end (4) is designed for attachment to a nostril and whose other end (5) opens out into the environment during use. Between the two tube ends (4 and 5) a tube part (3a) forms a pressure drop measurement stretch, which is delimited at both sides in each case by a tube connection piece (6 and 7) opening into the tube. The connection pieces can be connected to an evaluation arrangement (10) which comprises a differential pressure measurement stage (20) delivering an electrical output signal ( DELTA P), the differential pressure between the two connection pieces being a measure of the quantity of respiratory gas flowing through. These measures permit a safe measurement of the respiratory gas even in infants. <IMAGE>

Description

Respiratory analyzer

The present invention relates to a respiratory analyzer, with a breathing gas flow measuring head, which can be connected to a measuring arrangement is.

Breathing gas flowmeters of this type have already become known, which are offered under the name pneumotachometer and which are based on differential pressure measurements based.

The measuring head used here consists of a plurality of capillaries, which extend together and parallel to each other in a pipe. This capillary must have a very small diameter in order to be sufficiently large To win pressure drop for the downstream, relatively insensitive measuring arrangement.

The disadvantage of these arrangements is that the required large pressure drop requires breathing resistance for continuous measurements, which is only for adults, but not for newborns, children or toddlers is permissible. Likewise, the relatively high measuring ranges also only allow one Use in adults. The large ones caused by the design of the measuring heads Dead space volumes also mean an increased risk, especially for newborns of a C02 increase. In addition, there is a risk of the capillaries becoming blocked the breath secretions.

Other arrangements that control the breathing gas flow rate on thermoelectric Determining paths also appear to be of limited use, as incorrect measurements are here unavoidable due to the wetting of the thermistor sensor elements by condensates and secretions are.

It is now the object of the present invention to provide a respiration analyzer to create the former type, which allows the disadvantages of the known Arrangements to avoid and which in particular is absolutely safe to use in newborns and toddlers.

This is now achieved according to the invention in that the gas flow measuring head comprises a, a single flow channel limiting flow tube, the one end can be connected to a nostril and the other end into the environment opens out, between which two pipe ends, a pipe piece a pressure drop measuring section forms which section on both sides through a pipe connection opening into the pipe nozzle is limited, which nozzle can be connected to an evaluation device, which comprises a differential pressure measuring stage providing an electrical output signal, wherein the differential pressure between the two nozzles is a measure of the respiratory gas flow rate and the electrical output signal of this flow rate is analogous.

In particular by the measure, instead of a large number of capillaries now to use a measuring head with only one flow channel, the flow cross section of which of course expedient is much larger than that of a capillary, overall, however, can be kept smaller than the sum of the flow cross-sections of all capillaries of a previous measuring head, any risk of clogging can now be eliminated and the pressure drop can be reduced to just a few mm / Ws. Likewise through this Arrangement of the dead space volume to a fraction of this volume with the previous ones Limited measuring heads. Thus, all the conditions for a safe and effective Measurement of breathing gas in newborns and young children is guaranteed, of course the area of application of the device through appropriate dimensioning of the measuring head can also be extended to adults at will.

In a preferred embodiment, at least the pipe end that can be connected to a nasal opening by a bend of preferably formed over 900, which makes it easy to attach the measuring head to the patient's head Allowed in the area of the nose by means of adhesive tape or the like.

It is advantageous if in the area of the with a nostril connectable tube end in this a passage opening for inserting a catheter is provided. This then gives the option of using a thin plastic catheter, for example above insert the measuring head into the main bronchi in order to use it also measure the absolute tracheal or bronchial pressure without the Breathing gas flow measurement would have to be interrupted.

The present invention also relates to a method of operation of the aforementioned respiratory analyzer, which is characterized by that from the differential pressure signal the respiratory gas flow through time integration in Form of a minute flow or by integration over a breath as a volume flow is determined per move.

An example embodiment of the subject matter of the invention is now explained in more detail below with reference to the drawing.

They show: FIG. 1 a schematic representation of a respiration analyzer with a breathing gas flow measuring head, which is connected to an evaluation device and FIG. 2 is a graph showing the time profile of output signals on the evaluation device as a function of time.

The respiration analyzer shown in FIG. 1 comprises a respiratory gas flow measuring head 1, the flow channel 2 of which is delimited by a flow tube 3. With this one Flow tube 3 forms one end 4 of which can be connected to a nasal opening Elbow, which is preferably bent over 900 from a degree piece 3a. In Similarly, the other pipe end 5 can be bent, which into the environment empties. The straight pipe piece 3a forms between these two pipe ends a pressure drop measuring section, as will be explained in more detail below. Here is this measuring section 3a on both sides through a pipe exclusion nozzle opening into the pipe 3 6 or 7 limits which nozzle via suitable connecting means 8 and 9 with an essentially electronic evaluation device 10 are connected.

The measuring head 1 is also provided with a nasal bend 4 Connection piece 11 is provided, which surrounds a passage opening that of the introduction an expediently made of plastic catheter 12 is used. Suitable lanyards 13 again ensure a connection between the catheter and the evaluation device.

While in use the measuring head 1 preferably by means of a duct tape is attached to the head of a patient so that the bend 4 in the immediate If it reaches the area of a nasal opening, the catheter 12 can be used without interrupting the Breathing gas flow measurement through the nozzle 11 directly into the main bronchi to be introduced.

As can be seen from the illustration, the evaluation device now comprises 10 a differential pressure measuring stage 20 and a pressure measuring stage 30, which each membrane fine pressure meter with capacitive or inductive scanning.

The differential pressure measuring stage is now generated electronically in the usual way 20 an output signal # P, which is analogous to the flow rate for which the Differential pressure A P in mm / Ws between the two nozzles 6 and 7 of the measuring head 1 represents a measure.

The course of this flow as a function of time is through curve 201 in FIG. 2 illustrates.

On the other hand, the measuring stage 30 generates an output signal P, which is analogous to bronchial pressure.

The course of this absolute pressure as a function of time is illustrated by curve 301 in FIG.

The named output signals P and A P can now be evaluated as required and be connected directly to writing implements, for example. Furthermore, there is for example, the possibility of using the two signals A P and P to determine the dynamic compliance and to determine resistance values.

As FIG. 1 also shows, the output a # P of the measuring stage 20 also via a converter 21 to a first integrator 22 and a second Integrator 23 are supplied to from the differential pressure signal A P by time integration the minute flow or, by integrating it over one breath, the volume flow to be determined per breath. In the latter case there is of course the possibility to display the volume flow reduced by a determined dynamic dead space volume.

In a similar way, the output P of the measuring stage 30 can also have a Converter 31 are performed by means of a, the converter 31 downstream digital Level 32 only shows the pressure of each breath, which is synchronized with the flow in the lungs to be displayed.

It is clear that in addition to the embodiment described above other design variants are possible. In the first place, the shape of the Measuring head will certainly experience some deviations; for example, the manifold can be adjusted have on a face, and / or the pressure drop measuring section 3a has a curved one Have course. Furthermore, the evaluation device can have a number of further amplifier stages, Have converter stages, counting stages, integrating stages, etc., whereby in each case the necessary high sensitivity, the low inertia and a high zero point constancy must be maintained in order to be precise in spite of the slightest pressure drop on the measuring head and to achieve constant measurement results.

Claims (8)

Claims 1. Respiratory analyzer, with a breathing gas flow measuring head, which can be connected to a measuring arrangement, characterized in that the Breathing gas flow measuring head (1), a single flow channel delimiting Flow tube comprises, one end (4) of which can be connected to a nasal opening is and the other end (5) opens into the environment, between which two Pipe ends (4 and 5), a pipe piece (3a) forms a pressure drop measuring section, which Route on both sides through a pipe connection piece opening into the pipe (6 or 7) is limited which nozzle can be connected to an evaluation device (10) are the one differential pressure measuring stage that supplies an electrical output signal (a P) (20), the differential pressure between the two nozzles being a measure of the breathing gas flow rate and the electrical output signal of this flow rate is analog. 2. Respiration analyzer according to claim 1, characterized in that that at least the pipe end (4) that can be connected to a nostril is passed through a Bend of preferably over 900 is formed. 3. respiration analyzer according to claim 1 or 2, characterized in that that in the region of the pipe end (4) which can be connected to a nasal opening in this a passage opening for inserting a catheter (12) is provided. 4. respiration analyzer according to claims 1 and 3, characterized characterized in that the catheter is equipped with a further pressure measuring stage (30) of the evaluation device can be connected to generate a lung pressure signal (P). 5. respiration analyzer according to claim 1 and 4, characterized in that that the pressure measuring stages (20 and 30) membrane fine pressure gauges with capacitive or inductive scanning. 6. A method for operating the respiration analyzer according to claim 1, characterized in that the respiratory gas flow rate from the differential pressure signal (a P) by time integration in the form of a minute flow rate or by integration over one breath is determined as the volume flow rate per breath. 7. The method according to claim 6, characterized in that the volume flow a determined dynamic dead space volume displayed diminished will. 8. The method according to claim 6, characterized in that in addition a pressure (P) synchronized with each breath is determined in the lungs and from the both (AP and P) the dynamic compliance and resistance values can be determined.