Wheezing triggered by dorsal decubitus: pulmonary function changes

In 23 subjects with chronic obstructive pulmonary disease (COPD) who wheezed when changing their position from sitting to dorsal decubitus (DD), we recorded lung volumes and flow volume loops in sitting (S1), DD and immediately after resuming sitting (S2). We found three main patterns of ventilatory changes associated with wheezing in DD: (1) acute obstruction (AO) in 14 subjects characterized by FEV1 > or = -10% and %FEV1/FVC > or = -3%; functional residual capacity or residual volume was increased, decreased or unchanged; (2) acute restriction (AR) in 7 subjects characterized by absence of obstruction spirographically and FVC and/or FRC > -10%; (3) indeterminate response (IR) in 2 subjects. Except for 3 subjects, the changes recorded in DD returned to baseline in S2. Both AO and AR responses in DD and their rapid resolution in S2 were reproducible (11 subjects).

(1) in COPD, DD may trigger wheezing; (2) the physiologic changes during DD wheezing are reproducible, rapidly reversible when the sitting position is resumed and unlike those recorded during bronchoprovocation, heterogeneous.