Analysis of tracheal noise of forced human expiration according to clinical experimental data

The analysis of tracheal noise of forced expiration is one of the promising methods for the diagnosis of bronchial patency disorders, which are a sign of such widespread diseases as bronchial asthma and chronic obstructive bronchitis. The aim of this study is the verification and refinement of the acoustic model of forced expiration (Korenbaum et al., 1998) on the basis of a statistical analysis of clinical experimental data. A sample of 127 volunteers (from 18 to 74 years old) is used as an experimental statistical model: 34 persons suffering from bronchial asthma, 21 persons suffering from chronic obstructive bronchitis, 29 healthy persons, and 43 persons liable to developing the aforementioned diseases. The following parameters are analyzed: the total duration of noise of forced expiration at the trachea, the duration of wheeze of forced expiration with frequencies from 400 to 600 Hz, and the presence of narrowband high-frequency (over 600–700 Hz) spectral components at the end of forced expiration and during the whole expiration process. Reliable differences in the parameters of tracheal noise are revealed in the groups under study. The high prognostic value (a sensitivity of 89% and a specificity of 86%) of the parameters of tracheal noise of forced expiration, which were suggested a priori as the diagnostic parameters on the basis of the acoustic model (Korenbaum et al., 1998), indirectly confirms the adequacy of this model. The biomechanical-pathophysiological interpretation of the occurrence of acoustic deviations in the experimental sample groups provides an opportunity to relate the parameters of tracheal noise of forced expiration to the degree of mechanical nonuniformity of the lungs.