Airway obstruction in pulmonary sarcoidosis.

To determine the physiological basis of airway obstruction, we studied mechanical properties of the lung in 21 patients with various stages of pulmonary sarcoidosis. Forced expiratory flow at 50% vital capacity (VC) was significantly decreased in nine patients. Determining factors of the flow reduction factors of the flow reduction in addition to the decreased VC were: 1) low peripheral airway conductance in four patients; 2) loss of elastic recoil in three patients; 3) combination of 1) and 2) in two patients. These findings could be explained by a concept that in pulmonary sarcoidosis the lungs are a composite of inhomogeneously distributed normal, granulomatous, or fibrotic tissue, with or without hyperinflated tissue in various proportions.