The adult respiratory distress syndrome (ARDS) is characterized by refractory hypoxemia secondary to nonhydrostatic pulmonary edema and is associated with a wide variety of precipitating factors, many not directly involving the lung. Mortality has remained almost unchanged since the syndrome was first described in 1967. However, much is now known about the pathophysiology of the condition: histopathologic examination of tissue obtained from patients with ARDS suggests that the condition evolves through exudative, inflammatory, and fibro-proliferative phases Reading here.
However, the extent to which the pathologic changes that characterize ARDS are reflected in abnormalities of lung compliance and gas exchange remains unclear. Computed tomography (CT) has been used at single time points to evaluate possible relationships between CT density of lung parenchyma and gas exchange during the application of positive end-expiratory pressure (PEEP) and following changes in body position, but it has not been used to follow up survivors.
Furthermore, to our knowledge, no attempt has been made to correlate persistent morphologic abnormalities on CT in survivors with indices of respiratory function.
The aims of this study were therefore twofold: first, to extend previous work in this area by describing and quantifying the extent of lung injury in patients with ARDS with particular reference to those features that were potentially reversible, both during the acute and convalescent stages of the syndrome; and second, to relate any abnormalities to a severity score of lung injury.
In our unit, patients with ARDS who are considered fit enough undergo CT scanning for the evaluation of disease extent and detection of supervening complications are selected. The study population was confined to those who survived to be reviewed as outpatients.