Pulmonary function and exercise gas exchange in survivors of adult respiratory distress syndrome.

Pulmonary function studies were performed on 13 survivors of adult respiratory distress syndrome (ARDS). Six of these 13 patients had a forced vital capacity (FVC) and total lung capacity (TLC) less than 80% of predicted within 2 months of the onset of ARDS. Seven patients followed 6 months or more showed no significant difference between measured and predicted FVC (p = 0.26) or TLC (p = 0.12). The diffusing capacity of carbon monoxide was significantly lower than predicted normal values (p less than 0.001). Although the alveolar arterial oxygen tension gradient (delta AaPO2) was within the predicted normal range for 11 nonsmokers at rest, for 7 patients who exercised (1.0 less than VO2 less than 1.5 L/min), delta AaPO2 increased. The ratio of dead space to tidal volume decreased to less than 0.25 when VCO2 exceeded 1.0 L/min. We concluded that lung mechanics return to predicted normal values within 4 to 6 months after ARDS, but abnormalities of pulmonary gas exchange persist. Pulmonary vascular obstruction does not appear to explain persistent abnormalities of gas exchange.