Acute Respiratory Distress Syndrome Caused by Pulmonary and Extrapulmonary Injury: A Comparative CT Study

PURPOSE: To determine computed tomographic (CT) differences between acute respiratory distress syndrome (ARDS) due to pulmonary injury (ARDSp) and extrapulmonary injury (ARDSex).

MATERIALS AND METHODS: CT appearances in 41 patients (27 male, 14 female; mean age, 47.1 years ± 17.1 [SD]; age range, 17–79 years; those with ARDSp, n = 16; those with ARDSex, n = 25) were categorized as typical or atypical of ARDS by two observers. The extent of individual CT patterns was also quantified.

RESULTS: Typical CT appearances were more frequent in ARDSex than ARDSp (18 [72%] of 25 vs five [31%] of 16 patients, respectively; P < .01). Sensitivity, specificity, and accuracy of a typical CT pattern for the diagnosis of ARDSex were 72%, 69%, and 71%, respectively. Atypical appearances were characterized by more extensive nondependent intense parenchymal opacification (IPO) (P = .03) and cysts (P = .05), whereas typical CT appearances had more extensive dependent IPO (P = .01). Typical appearances at CT were independently related to the cause of ARDS (odds ratio, 8.9; 95% CI: 1.8, 44.2; P < .01) but were independent of the time from intubation. Foci of nondependent IPO were more extensive in ARDSp (P = .05) than ARDSex, but this finding was ascribable to differences in time to CT (after intubation) between ARDSp and ARDSex.

CONCLUSION: The differentiation between ARDSp and ARDSex can, with some caveats, be based on whether the CT appearances are typical or atypical of ARDS but not on any individual CT pattern in isolation.


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Article History

Published in print: Mar 2001