DE102006011900A1 - IOS measuring station and IOS measuring method - Google Patents

Abstract

The invention relates to an IOS measuring station with a flow tube (2) and a pressure-flow measuring head (4), which is pneumatically connected to the flow tube. A valve (9) connects the flow tube (2) to a compressed air source (14) or separates the flow tube (2) from the compressed air source (10, 14) in order to generate air pressure fluctuations in the flow tube.

Description

The Technical field of the invention are pulse-oscillometric measuring stations (IOS measuring stations) according to the preamble of claim 1 and IOS measuring method according to the generic term of claim 6. IOS measuring stations and IOS measurement methods are used to determine airway resistance.

IOS measuring stations will be For example, under the product name MasterScreen IOS by the VIASYS Healthcare GmbH (http://www.jaeger-toennies.com/english/PRODUKTE/Pneumologie/Impulsoszillometrie/IOS/ios.htm) distributed.

An IOS measuring station according to the prior art is exemplary in FIG 2 shown. The heart of the measuring station is a river tube 2 which in turn is a pressure-flow measuring head 4 , a mouthpiece 3 , a Y-piece 8th as well as a terminator 20 includes. At the river tube 2 is also a speaker 18 connected to generate air pressure fluctuations. The terminator 20 prevents an acoustic short circuit and ensures that a significant portion of the speaker 18 generated sound energy through the flow tube 2 in the respiratory tract of the patient 23 and is available for a measurement.

The pressure flow measuring head 4 captures both the differential pressure between the interior of the flow tube 2 and the environment as well as the correct sign the air flow from and to the patient 23 , In the in 1 illustrated, known embodiment, the air flow measurement is carried out indirectly via the measurement of the pressure drop across a porous disk 7 , The pressure drop is via the differential pressure sensor 5 detected.

If required, an aerosol provocation system (APS) 16 which is also distributed by VIASYS Healthcare GmbH. The measuring station is controlled by a computer 13 controlled. There is a comfortable evaluation and presentation software available.

Of the Loudspeaker gives a sound impulse of a length of 45 ms with a frequency spectrum of 0-100 Hz. The pulse is repeated after 0.1 to 10 seconds. The air flow measuring range is ± 20l / s. In the range between 0.2 to 12 l / s the accuracy is ± 2%. The Oral pressure measurement is in the range of ± 2 kPa with accuracy less than ± 2%.

With such an IOS measuring station can under other, the amount of respiratory impedance Z5, the total Respiratory resistance R5, the proximal breathing resistance R20, the distal capacitive reactance X5 and the resonance frequency Fres are determined.

It It is an object of the invention to provide a more compact IOS measuring station as well specify an appropriate IOS measurement method.

These The object is achieved by the teaching of the independent claims.

preferred embodiments The invention are the subject of the dependent claims.

Advantageous on a valve compared to a speaker is the smaller one Design. This leads to, that the pressure fluctuations closer can be generated at the mouth of the patient and therefore the flow tube be made shorter can. Thus, the flowmeter affects the breathing process less and provides more meaningful readings.

Advantageous at a tank or reservoir, which is connected to the inlet of the valve connected is that so stronger Air pressure fluctuations can be generated. The tank stores air under overpressure and thus compensates the flow resistance of a supply hose z. Between the compressed air supply of a hospital and the IOS measuring station, if the valve is only opened for a short time.

The The ideal pulse shape of an air pressure fluctuation is a Dirac delta function. The air pressure fluctuation, the one opening of the valve for 10 ms, this ideal pulse shape comes closer than that with a loudspeaker generated pulse shape.

in the Below is a preferred embodiment of the invention below With reference to the accompanying drawings explained in more detail. Showing:

1 an IOS measuring station according to the invention; and

2 a well-known IOS measuring station.

The main difference between the in 2 shown, conventional IOS measuring station and the in 1 illustrated, IOS measuring station according to the invention is that the speaker through a valve 9 was replaced. The valve 9 connects the river tube 2 over a tank 10 , a connection 15 with a compressed air source 14 , At the compressed air source 14 it can be, for example, the compressed air supply of a clinic or a gas bottle or gas cartridge. The connection 15 provides a detachable connection to the pressure air source 14 to give the IOS measuring station a certain flexibility.

When briefly opening the valve 9 arises in the river tube 2 a pressure pulse used to determine various parameters of the patient's airway. The opening time of the valve between opening and closing may be for example 10 ms. Assuming that a constant air flow flows during valve opening, the frequency spectrum is A / f · sin (2π (10ms) f), where A is the amplitude and f is the frequency. The zeros are k · 100Hz, where k = 1, 2, 3 .... Frequency components up to 35Hz are of particular interest for the diagnosis. A shortening of the opening time under 10 ms brings little. It causes the zeros in the frequency spectrum to move to higher frequencies and overall a wider frequency spectrum is generated. Rather, the reverse is a shoe: The opening and closing behavior of the valve and thus the shape of the pressure wave is advantageously designed so that the frequency components are mainly included below 35Hz in the spectrum. Opening and closing the valve 9 is about computer 13 controlled.

The evaluation can be done by removing from the pressure flow measuring head 4 supplied pressure and flow signal at 5 Hz and 20 Hz each a complex coefficient is calculated. From the complex coefficients calculated at 5 Hz, the respiratory impedance Z5, the total breathing resistance R5 and the distal capacitive reactance X5 are then calculated. From the complex coefficients calculated at 20 Hz, the proximal breathing resistance R20 is calculated.

Around the diagnostic quality to increase, can both the pressure and the flow signal of a fast Fourier transform (FFT) and respiratory parameters such as the respiratory Impedance, respiratory resistance and reactance in dependence graphed by the frequency.

The Tank 10 serves as a pressure reservoir and thus lowers the impedance of the compressed air source 14 when briefly opening the valve 9 , The Tank 10 can be like in 1 shown serially between the port 15 and the valve 9 hang. The Tank 10 can in the simplest case by the volume of a supply hose with a sufficiently large radius between the connection to the compressed air supply to a clinic and the valve 9 be formed to compensate for the flow resistance of the valve following the compressed air supply to the clinic.

In another embodiment, a check valve 21 provided that prevents air from the tank 10 through the connection 15 is discharged when the connection 15 is open. The check valve can - as in 1 shown - in the tank 10 , in the connecting hose between the tank 10 and the connection 15 or afterwards 15 be housed. If in this embodiment the tank 10 sufficiently large, the tank can 10 itself as a source of compressed air for a certain period of time, and thus the IOS measuring station 1 be operated independently of, for example, the compressed air supply to a clinic before the tank 10 must be refilled again.

In another embodiment, the tank 10 only one port on, which has a second Y-piece with both the inlet of the valve 9 as well as with the connection 15 is pneumatically connected. In this embodiment, the check valve is connected 15 or in the connection hose between Y-piece and connection 15 accommodated. The inserted pressure flow measuring head 4 can, as in 2 shown, a porous disk 7 as air flow resistance and a differential pressure sensor 5 for determining the air flow from a differential pressure and a further differential pressure sensor 19 for measuring the differential pressure between the mouth pressure and the ambient pressure. Both differential pressure sensors are position and temperature compensated. The differential pressure sensor 19 is mounted as close to the mouthpiece as possible to reduce the pressure drop between the mouth and the differential pressure sensor 19 to keep low. The differential pressure sensors 5 and 19 can be replaced by three pressure sensors, the latter being the pressures left and right of the porous disk 7 and measure the ambient pressure, but at the moment leads to higher costs. In another embodiment, differential pressure sensor 5 or differential pressure sensor 19 be replaced by two pressure sensors.

In the in 1 illustrated embodiment, a differential pressure sensor 19 as well as an ultrasonic spirometer 17 used for detecting the mouth pressure or the air flow.

With known air flow can with the differential pressure sensor 19 measured pressure around the pressure drop across the piece of the flow tube between the differential pressure sensor 19 and the mouthpiece 3 be compensated.

In further embodiments can other flow sensor types, such as rotation frequency transmitters (RFG) or heating wire-based flow sensors are used.

The river tube 2 can in a resistance tube 11 which is smaller in diameter than the rest of the flow tube 2 having. Due to the smaller diameter, the resistance tube 11 a significant flow resistance and thus serves as a terminating resistor 20 , Additionally or alternatively, a porous body 12 as a terminator 20 serve.

Like in the 1 represented, the Y-piece can 8th be shaped so that the valve 9 Coming pressure wave especially to the patient 23 and less to the resistance tube 11 is steered. This will be in 1 achieved by acting as a mirror diagonal interface of the Y-piece. In another embodiment, the valve 9 be placed on the predetermined axis of the river tube, whereas the resistance tube is arranged at an angle relative to this axis.

Also at the in 1 illustrated embodiment, an APS 16 be used. As in the embodiment of the invention, the connection to a compressed air source 14 is necessary, the compressed air source can 14 also for the atomization of medicine or irritants in the APS 16 be used. This simplifies the design of the APS, because only one hose 22 for connecting the APS, for example via the tank 10 to the compressed air source 14 but no compressor is needed anymore. The Tank 10 can also temporarily serve as a compressed air source for the APS.

The The invention was previously based on preferred embodiments explained in more detail. For one However, one skilled in the art will appreciate that various modifications and modifications can be made without departing from the spirit of the invention. Therefore, the scope of protection by the following claims and set their equivalents.

1

IOS measuring station

2

flux tube

3

mouthpiece

4

Pressure-flow probe

5

Differential Pressure Sensor

7

porous disc

8th

Y-piece

9

Valve

10

tank

11

resistance tube

12

porous body

13

computer

14

Compressed air source

15

connection

16

APS

17

Ultrasonic spirometer

18

speaker

19

Differential Pressure Sensor

20

terminator

21

check valve

22

tube

23

patient

Claims (9)

IOS measuring station with: a flow tube ( 2 ); a pressure flow measuring head ( 4 ), which is pneumatically connected to the flow tube; a device for generating pressure fluctuations in the flow tube ( 2 ); characterized in that the device for generating air pressure fluctuations is a valve ( 9 ) with an inlet and an outlet, the outlet being pneumatically connected to the flow tube ( 2 ) and the inlet with a compressed air source ( 10 . 14 ) is connectable. IOS measuring station according to claim 1, characterized in that a tank ( 10 ) with the inlet of the valve ( 9 ) is pneumatically connected. IOS measuring station according to one of the preceding claims, characterized in that the IOS measuring station further comprises a controller ( 13 ), which is the valve ( 9 ) repeatedly open for 10 milliseconds. IOS measuring station according to one of the above claims, characterized in that the pressure flow measuring head ( 4 ) an ultrasonic spirometer ( 17 ) for measuring the air flow. IOS measuring station according to one of the above claims, characterized in that the IOS measuring station has an APS which is connected to the compressed air source ( 10 . 14 ) is pneumatically connected (22). IOS measuring method with: measuring the pressure and the respiratory flow in a flow tube ( 2 ) with a pressure-flow measuring head ( 4 ); Generation of air pressure fluctuations in the flow tube ( 2 ); characterized in that the air pressure fluctuations by the opening and closing of a valve ( 9 ), wherein the valve ( 9 ) the river tube ( 2 ) when opening with a compressed air source ( 14 ) pneumatically connects and when closing the flow tube ( 2 ) from the compressed air source ( 14 ) separates. IOS measuring method according to claim 6, characterized in that air is closed when the valve ( 9 ) from the compressed air source ( 14 ) in a tank ( 10 ) and with the valve open ( 9 ) from the tank ( 10 ) in the river tube ( 2 ) flows. IOS measuring method according to claim 6 or 7, characterized characterized in that the valve is opened for 10 ms. IOS measuring method according to one of claims 6 to 8, characterized in that the respiratory flow with an ultrasonic spirometer ( 17 ) or a rotational frequency encoder is measured.