Plethysmographic Assessment of Trapped Air in Man

Publisher Website
Google Scholar
Abstract
An obstructive disorder in lung function is diagnosed on the basis of an increase in bronchial flow resistance (R), associated with a decrease in FEV1 (in terms of measured vital capacity) and with a residual volume (RV) appreciably higher than the theorectical value. Total lung capacity (TLC) is likewise elevated, while vital capacity (VC) is reduced. In obstructive disorders of lung function, body plethysmography yields residual volumes which are considerably larger than those obtained with the helium dilution method. The difference between the lung volumes determined by the 2 methods is usually interpreted as being due to trapped air. This compressed and decompressed volume of air (V₀) which does not participate in ventilation, is of decisive quantitative importance for the plethysmographically measurable difference in chamber pressure (ΔPo) between end of inspiration and end of expiration when flow at the mouth is zero (V = O). The presence of trapped air can thus be detected directly on the basis of the plethysmographic pressure (▵p) and flow (V) diagram. As expected, however, there is not a good correlation between the volume (Vo) and the plethysmographic chamber pressure (ΔPo)·

This publication has 0 references indexed in Scilit: