Evaluation of Definitions for Adult Respiratory Distress Syndrome

We conducted a cohort study of 423 intensive care unit (ICU) admissions with a primary clinical diagnosis of acute respiratory failure, a PaO2/FIO2 on ICU admission of 90% in both groups. We conclude that ARDS is a complex clinical entity with a variety of pulmonary and nonpulmonary risk factors for both its development and its prognosis. Current and proposed categorical definitions based on the severity of hypoxemia result in a wide distribution of individual patient risks. Use of these findings in the design and conduct of future clinical trials would improve the evaluation of new therapies.