[Reduction of pulmonary capillary volume following acute respiratory distress syndrome in adults].

Lung function after adult respiratory distress syndrome was evaluated in 8 survivors whose ages ranged from 20 to 54 years. At the time of the study, 5.5 to 19 months after extubation, all patients were asymptomatic at rest but 6 had mild to moderate exertional dyspnea. Physical examination was normal in 7 patients; lung volumes, flow rates and pulmonary mechanics were minimally altered, mainly in smokers. Chest X-rays showed no major abnormalities. On graded submaximal exercise test, performance was limited by tachycardia and not by ventilation. Resting arterial PO2 was low in 6 patients and increased only in one patient during submaximal exercise. The capillary blood volume was decreased in all patients. The mechanisms of hypoxia during exercise and decreased capillary blood volume, the latter apparently unrelated either to pulmonary microvascular obstruction or to fibrosis, remain unexplained. It is concluded that lung volumes and pulmonary mechanics are restored to normal within 6 months after ARDS, whereas gas exchanges persist after ARDS and are associated with a reduced pulmonary blood volume.