Indications for extracorporeal support: why do we need the results of the EOLIA trial?

Acute respiratory distress syndrome (ARDS) is a severe lung disease, with an associated mortality rate exceeding 60% for the most severe forms of the disease. In these situations, establishing an extracorporeal circuit, combining a centrifugal pump and a membrane oxygenator (extra-corporeal membrane oxygenation, ECMO), can ensure total pulmonary assistance and allow the lungs to rest under ultraprotective mechanical ventilation. Unfortunately, former trials of ECMO in ARDS were negative or highly criticized due to many technical and methodological shortcomings. Prior to the widespread use of venovenous ECMO for severe ARDS, new trials are needed to test the efficacy of early initiation of the technique with tight control of mechanical ventilation in the control group, initiation of ECMO prior to transportation to ECMO centers, and the use of ECMO in all patients randomly assigned to receive this treatment. Therefore, the international multicenter randomized EOLIA (ECMO to rescue Lung Injury in severe ARDS) trial was designed to test the benefit of systematic and early installation of the latest-generation ECMO circuits in patients with very severe ARDS. Patients randomized to the control group were managed with tight control of mechanical ventilation and recourse to paralyzing agents and prone positioning, while an ethical crossover option to ECMO was permitted only if refractory hypoxemia (SaO₂ < 80%) lasted for > 6 h despite all possible conventional emergency interventions. The primary endpoint of the study was the 60-day mortality rate, with an expected 20% absolute mortality reduction with ECMO.