COMPARATIVE SENSITIVITY OF FREQUENCY DEPENDENCE OF COMPLIANCE AND DIFFERENTIAL BRONCHIAL PRESSURE IN DETECTING PERIPHERAL ASYNCHRONOUS TIME CONSTANTS.

Several investigators in the past have suggested different techniques to assess to status of the small airways (2-3 mm diameter). These are the site of diseases such as chronic bronchitis, emphysema and some cases of asthma. However, the contribution of these small airways is less than 20% of the total resistance to breathing, since the total cross-sectional area is very large. Thus, it is not possible to measure the small changes occurring in these peripheral units as a part of the total resistance measured during opontaneous breathing. A. J. Woolcock et al. showed that dynamic jcompliance (C//d//y//n) decreases at higher breathing frequencies (up to 100 breaths/min) in subjects whose predominant disease is in the small airways. The frequency dependence of C//d//y//n is now the accepted test for the sensitive detection of small airway diseases. The authors have investigated a new technique which could be more sensitive compared to this test for the detection of events occurring in the peripheral (small) airways.