Pulmonary function and the pathogenesis of obstructive sleep apnea syndrome

Abstract We studied the relationships between results of pulmonary-function tests and sleep-induced respiratory disorders in men with obstructive sleep apnea syndrome (OSAS). Pulmonary-function tests were done in 23 men with OSAS and in 9 men without OSAS who were matched for age and body mass index. Tests were done both in sitting and in supine positions. For both positions, results of pulmonary-function tests did not differ between the OSAS and the non-OSAS groups. In both groups, %TLC, %FRC, PaO2, and V25/Ht were lower while supine than while sitting, and CC/FRC was higher. In both positions, CC/FRC was significantly and positively correlated with apnea index and with 4% desaturation time. Body mass index was not correlated with apnea index or with 4% desaturation time. These findings suggest that low lung volume and peripheral airway closure contribute to sleep-induced respiratory disorders in men with OSAS, regardless of the body mass index.