It is estimated that at least 150,000 individuals die each year of adult respiratory distress syndrome. Treatment remains largely supportive. The National Heart, Lung, and Blood Institute (NHLBI) conducted the Extracorporeal Support for Respiratory Insufficiency (ECMO, Extracorporeal Membrane Oxygenation) trial from June 1974 through 1978. In ECMO, 90 patients were randomized to either extracorporeal membrane oxygenation plus conventional therapy or to conventional therapy. Survival rates were less than ten percent in both groups. The failure of the trial to demonstrate the superiority of ECMO over conventional ventilatory support resulted in the virtual elimination of the use of ECMO in clinical medicine.