Effect of prone positioning on the survival of patients with acute respiratory failure

Background: Although placing patients with acute respiratory failure in a p rone (face down) position improves their oxygenation 60 to 70 percent of th e time, the effect on survival is not known. Methods: In a multicenter, randomized trial, we compared conventional treat ment (in the supine position) of patients with acute lung injury or the acu te respiratory distress syndrome with a predefined strategy of placing pati ents in a prone position for six or more hours daily for 10 days. We enroll ed 304 patients, 152 in each group. Results: The mortality rate was 23.0 percent during the 10-day study period , 49.3 percent at the time of discharge from the intensive care unit, and 6 0.5 percent at 6 months. The relative risk of death in the prone group as c ompared with the supine group was 0.84 at the end of the study period (95 p ercent confidence interval, 0.56 to 1.27), 1.05 at the time of discharge fr om the intensive care unit (95 percent confidence interval, 0.84 to 1.32), and 1.06 at six months (95 percent confidence interval, 0.88 to 1.28). Duri ng the study period the mean (+/-SD) increase in the ratio of the partial p ressure of arterial oxygen to the fraction of inspired oxygen, measured eac h morning while patients were supine, was greater in the prone than the sup ine group (63.0+/-66.8 vs. 44.6+/-68.2, P=0.02). The incidence of complicat ions related to positioning (such as pressure sores and accidental extubati on) was similar in the two groups. Conclusions: Although placing patients with acute respiratory failure in a prone position improves their oxygenation, it does not improve survival.