DCO at Various Breath-Holding Times: Comparison in Patients with Chronic Bronchial Asthma and Emphysema

Publisher Website
Google Scholar
Abstract
Measurement of DCO [diffusion capacity of CO] is dependent upon functional inhomogeneities. Because different types of inhomogeneities are operative in patients with bronchial asthma and patients with emphysema, different changes of DCO with increasing breathholding time, TA, are to be expected. The change of DCO with increasing breathholding time was studied in healthy subjects, patients with asthma bronchiale and patients with emphysema. In the patients the severity of airway obstruction was about the same. In healthy subjects and in the asthmatics DCO decreased with tA, in a similar manner, approaching a value (ml .cntdot. min-1 .cntdot. Terror-1) of 34.7 and 31.6 at 10 s, respectively, and in patients with emphsema DCO increased with tA, yielding negative values at small tA: 1.5 s-23.4; 10 s: 11.7. In healthy subjects and in patients with bronchial asthma parallel inhomogeneities apparently influence the course of DCO. In emphysema the time course of DCO is best explained with a faster intrapulmonary mixing of He compared to CO. This behavior indicates that in emphysema low DCO values can be mainly attributed to large diffusional resistances (stratification) within the lungs.