Radiographic issues in adult respiratory distress syndrome.

Despite significant technical limitations, the portable chest radiograph remains the primary tool for radiographic evaluation of patients with the acute respiratory distress syndrome (ARDS). Using good-quality films, experienced observers usually can distinguish permeability-induced from nonpermeability-induced pulmonary edema. In patients with ARDS, the chest radiograph typically shows rapid dramatic deterioration within 24 hrs, as indicated by the development of patchy peripheral infiltrates. Radiographic density may increase in severity for 5 to 7 days, after which time, further deterioration usually signals the occurrence of another process (e.g., infection, fluid overload). In the period beyond 1 wk, where the radiograph usually remains relatively stable, the chest radiograph is most useful in detecting complications of therapy, predominantly barotrauma. The vast majority of survivors of ARDS show improvement in their radiographs within the first 10 to 14 days after the onset of illness. Failure to show improvement during this time is a poor prognostic factor. Computed tomography is a useful modality in patients with questionable chest radiograph findings, provided that the patients are stable enough to leave the ICU for evaluation.