Apparatus for pulmonary function analysis

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.