Surgery – Truss – Pad
Patent
1994-01-31
1995-05-30
Manuel, George
Surgery
Truss
Pad
7386128, 128719, A61B 800
Patent
active
054193265
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a spirometer, more particularly an ultrasonic spirometer, in the case of which a pair of cells, of which one is a transmitter cell and the other is a receiver cell, are arranged in a test section with an oblique or perpendicular alignment to the axis of the test duct.
Spirometry, that is to say the measurement of air movements in the course of breathing, is generally performed using measuring instruments which measure the volumetric flow of a gas in a duct by determining the velocity of flow. The volumetric flow may be found as the product of the cross section of the duct and the mean velocity of flow. In the case of the use of a measuring instrument for the investigation of the performance of the human lung the variations in the volumetric flow with time during breathing in and out are of interest. By integration it is possible to determine the quantity of air breathed in or out in a certain period of time. Presently various methods of flow measurement are employed in pulmonary function diagnostics (pneumotachography). There are methods such as measurement of back pressures upstream from a constant resistance (for example woven metal fabric) or using Fleisch pneumotachographs, measurement using a propeller, measurement using a thermistor and other methods.
The patent publications JP 60-117149 A and CH 669463 A5 disclose so-called ultrasonic spirometers of the type initially mentioned, in the case of which a transmitter cell and a receiver cell are arranged in a test section with an oblique or perpendicular alignment to the axis of the test duct. In these known ultrasonic spirometers the flow velocity is determined using ultrasonic doppler measurement. This measuring technique renders possible an accurate determination of the flow field on the axis of the test duct section and consequently an exact determination of the volumetric flow. In the case of spirometry such measuring instruments do however suffer from the disadvantage the test duct section may be contaminated with microorganisms and the like. Therefore it is necessary for the tube to be disinfected after each measurement, something which is on the one hand expensive and on the other hand represents a continual danger of infection if it is not performed properly.
One solution to this hygienic problem has been attempted by the development of so-called disposable sensors. Accordingly attempts have already been made to provide the test duct through question the respiratory gas flows with a nozzle-like restriction with a tube joining it at its narrowest point to provide a connection for the measuring device. This duct with the nozzle-like restriction, which is contaminated with respiratory air is now to be designed as a disposable item, which can be replaced after being employed once. This solution, which is valuable from the point of hygiene, does however lead to the danger of interference with the flow to be measured and for this reason spurious readings.
One object of the present invention is to provide such a further development of the spirometer of type described that measurement of the flow velocity free of interference while ensuring the required hygienic precautions is rendered possible.
Taking as a starting point a spirometer of the type initially mentioned this object is to be attained by the characterizing features of claim 1. Accordingly a readily replaced and if necessary sterile tube is inserted into the test duct of the ultrasonic spirometer with an accurate fit. At the transition with the test section the replaceable tube possesses windows of that type in which inserts are placed, which on the one hand allow the passage of sound waves but on the other hand are substantially impermeable to germs. This design is based on the thought that in the part in which the test section opens towards the axis of the test duct, windows are present which allow the passage of ultrasonic vibrations, since the wall surface of an inserted lining duct would excessively damp the ultrasonic waves and consequently would render any ultr
REFERENCES:
patent: 3738169 (1973-06-01), Courty
patent: 3901078 (1975-08-01), McShane
patent: 5035147 (1991-07-01), Woodward
Manuel George
NDD Medizintechnik GmbH
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