Early Application of Positive End-Expiratory Pressure in Patients at Risk for the Adult Respiratory-Distress Syndrome

Previous studies have suggested that the early application of positive end-expiratory pressure (PEEP) reduces the incidence of the adult respiratory-distress syndrome. We randomly assigned 92 patients with a known risk for this syndrome to receive mechanical ventilation either without PEEP (control) or with early PEEP at 8 cm H2O. These therapies continued for 72 hours unless respiratory distress developed or arterial oxygen tension was above 140 (fractional inspired oxygen concentration, 0.5) at 24 hours or later and remained at that level after removal of PEEP. The study was designed to have an 80 per cent probability of detecting a 60 per cent reduction in the incidence of the syndrome. The treatment groups were comparable in age, severity of injury, number and type of risk factors for adult respiratory-distress syndrome, and initial oxygenation. The syndrome developed in 11 of 44 patients given early PEEP (25 per cent) and in 13 of 48 control patients (27 per cent). The incidence of atelectasis, pneumonia, and barotrauma was the same in both groups, as was mortality. We found that the early application of PEEP at 8 cm H2O in high-risk patients had no effect on the incidence of the adult respiratory-distress syndrome or other, associated complications.