US 4,307,730 AGranted

Apparatus for pulmonary function analysis

AssigneeSiemens Aktiengesellschaft

InventorVolker Korn

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Abstract

For the measurement of functional respiratory volume, or respiratory capacities, apparatus are known including a respiratory bag which can be connected to a respiratory tube via a first valve system and which can be connected to test gas receptacles via an additional valve system and which exhibit gas analysis devices for measurement of the test gas concentration in the respiratory bag. Precise concentration measurements have been hitherto possible only discontinuously with chemical methods, or continuously with a large apparatus outlay (mass spectrometer). By way of a contrast, simple thermal conductivity sensors are unsatisfactory in measuring precision. According to the present disclosure, the concentration determination proceeds by means of a gas analysis device through continuous density determination of the mixture of test gas and respiratory air in the respiratory bag, for which purpose a measuring probe can be introduced into the respiratory bag by means of a separate connection, and the gas density-dependent measuring signal corresponding to the present test gas concentration, which signal has been tapped at the measuring probe can be directly displayed as the pulmonary function measured value (RV, FRC). In this manner the determination of respiratory volumes, or respiratory capacities, respectively, is substantially simplified.

Claims11

Dependent claims

Apparatus for pulmonary function analysis, comprising:

respiratory bag means for receiving a test gas,
mouthpiece means for receiving the mouth of a patient, a valve system controlling fluid connection of said mouthpiece means with said respiratory bag means,
gas supply means for supplying test gas to said respiratory bag means,
density measuring means coupled with respiratory bag means,
means for filling said respiratory bag means with a test gas from said gas supply means and for operating said density measuring means to register a test gas density value (U.sub.B) repesenting the density of the test gas in said respiratory bag means, and
means comprising said valve system for connecting said mouthpiece means with said respiratory bag means after the filling thereof with said test gas and for operating said density measuring means to register a succession of values of the density of the test gas and respiratory air in said respiratory bag means as a patient inhales and exhales until an equilibrium value (U.sub.M) of density is registered at said density measuring means, whereby in conjunction with a measured value of the density of room air (U.sub.L), a measure of at least one of functional respiratory capacity (FRC) and residual volume (RV) is defined,
characterized in that the density measuring means comprises a measurement passage, means coupled with said measurement passage for impressing a defined alternating flow (v.about.) of a known frequency on the respiratory bag means, and means whereby the alternating pressure (p.about.) developing in the measurement passage relative to the external pressure is measured as the gas density-dependent signal.

4 more elements

Dependencies are inferred from the claim text.