Reduced pulmonary capillary blood volume as a long-term sequel of ARDS

Lung function was evaluated in nine survivors of ARDS. All patients were asymptomatic at rest at the time of the study, ie, 5.5 to 19 months after extubation (mean 12.5). Six had mild to moderate exertional dyspnea. Chest x-ray films showed no gross parenchymal abnormalities. Spirometry and pulmonary mechanics were either normal or minimally altered, particularly in smokers. At submaximal exercise levels, effort was limited by tachycardia in eight patients; one subject showed ventilatory and cardiovascular limitations. It was concluded that spirometry and pulmonary mechanics are restored to normal within six months after extubation, and gas exchange abnormalities persist after ARDS and might be related to intrapulmonary shunts at rest, whereas during exercise a decreased pulmonary capillary blood volume might be the primary factor.