The behavior of pulmonary resistance (R(L)) and that of dynamic compliance (C(dyn)) as functions of respiratory frequency (f) were compared in normal subjects and in patients with chronic obstructive pulmonary disease (COPD). Although both R(L) and C(dyn) varied with f in most COPD patients and in some normal subjects, C(dyn) appeared to be more sensitive than R(L) to variations of frequency; no significant changes in R(L) could be demonstrated in subjects in whom C(dyn) was frequency dependent. The degree of frequency dependence of C(dyn) was correlated with the severity of respiratory impairment (as quantified by conventional pulmonary function tests); in contrast, R(L) was not detectably frequency dependent in some subjects with advanced COPD. Compared with C(dyn), R(L) was more commonly nonlinearly related to respiratory frequency, often increasing at high breathing rates. Our results indicate that changes in R(L) with frequency are less predictable and more difficult to detect than the corresponding changes in C(dyn).
|Number of pages||9|
|Publication status||Published - 1983|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine