BACKGROUND:

The report of the Task Force on Respiratory Diseases identified a clinical syndrome of acute respiratory insufficiency (ARI) and estimated that approximately 60,000 Americans die of ARI yearly. ARI was not precisely defined; indeed, the Task Force realized that pathologists do not recognize ARI. The Task Force pointed out that no diagnostic tests for early detection of ARI exist, that the incidence and prevalence of the disease are not known, and that existing therapy is supportive and nonspecific (diuretics, corticosteroids, etc.). The pathogenesis of the syndrome, the mechanism of interstitial edema, the defenses of the lung against agents causing ARI, and the ultrastructural pathology and natural history of the disease were virtually unknown. The Task Force indicated a need for Respiratory Care Centers with highly trained personnel that could reduce mortality from ARI.

This clinical trial grew out of the Task Force report. Nine participating centers defined ARI in clinical and physiological terms and agreed to a prospective randomized study for 3 years to compare treatment of severe ARI by conventional means with treatment by extracorporeal membrane oxygenators.

Animal studies have shown that ECMO's can provide one to two weeks' support for the lungs without serious blood damage, in contrast to bubble oxygenators, which allow complete pulmonary bypass for approximately 6 hours, after which severe blood damage occurs at the direct blood-gas interface. If patients with hypoxia secondary to acute reversible lung injury can be supported with ECMO's until the lung lesion heals, improvement in survival rates and avoidance of the hazards of conventional therapy may result. The trial, now completed, was conducted at nine clinical centers in the United States.

DESIGN NARRATIVE:

Randomized, non-blind, fixed sample; 90 eligible patients were randomly assigned to a group receiving extracorporeal membrane oxygenation plus conventional therapy or to a group receiving conventional therapy.