Frequency dependence of regional lung washout

Publisher Website
Google Scholar
Abstract
Regional 133Xe washout was measured simultaneously with whole lung washout, measured at the mouth, at 2 breathing frequencies (12 and 57 breaths/min) in 9 asymptomatic men. During slow breathing, the alveolar ventilation required to reduce 133Xe concentrations by 50% (VA1/2) [alveolar ventilation] decreased from apex to base, and mouth VA1/2 was within the range of regional values. Rapid breathing did not alter the vertical gradient, but increased VA1/2 of all lung regions (P < 0.05) without changing mouth VA1/2. The relationship between regional washout and whole lung washout was frequency dependent, reflecting a functional heterogeneity of units within each lung region. The mechanism responsible for this intraregional frequency dependence appeared to be parallel time constant inequality, rather than series inhomogeneities or inadequate gas mixing of parallel inhomogeneities, on the basis of the following results. Frequency dependence of washout was significantly less after a rapidly vs. a slowly inspired 133Xe bolus. Frequency dependence of dynamic compliance correlated with frequency dependence of washout (P < 0.05). Frequency dependence on a gas of reduced diffusivity (80% SF6-20% O2) was not significantly different from that of air.

This publication has 2 references indexed in Scilit: