Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome

Original: N Engl J Med 2018; 378: 1965-1975

Author(s): Alain Combes, David Hajage, Gilles Capellier, Alexandre Demoule, Sylvain Lavoué, Christophe Guervilly, Daniel Da Silva, Lara Zafrani, Patrice Tirot, Benoit Veber, Eric Maury, Bruno Levy, Yves Cohen, Christian Richard, Pierre Kalfon, Lila Bouadma, Hossein Mehdaoui, Gaëtan Beduneau, Guillaume Lebreton, Laurent Brochard, Niall D. Ferguson, Eddy Fan, Arthur S. Slutsky, Daniel Brodie and Alain Mercat for the EOLIA Trial Group, REVA, and ECMONet*

Reviewer: Julien Guiot

In the EOLIA trial, Combes et al. evaluates the benefit on 60-day mortality of patients suffering from very severe acute respiratory distress syndrome (ARDS) by applying immediate extracorporeal membranous oxygenation (ECMO) compare to traditional therapy. Very severe ARDS was defined by a PaO2/FIO2 ratio under 50mmHg 3 hours or under 80mmHg 6 hours, or by an arterial blood pH of less than 7.25 with a PaCO2 of at least 60 mmHg for more than 6 hours. Crossover from the control arm to ECMO treatment was allowed if prolonged periods of arterial oxygen desaturation to < 80% occurred.

They randomized 249 patients (1:1) to evaluate the overall mortality at 60 days. 28% in the control group benefit from an ECMO as a rescue therapy. The ECMO group exhibit principally more bleeding event (in 46% vs. 28%), more severe thrombocytopenia (in 27% vs. 16) but fewer cases of ischemic stroke (in no patients vs. 5%). The study was terminated for futility after 67 months. There was an 11% reduction in absolute 60-day mortality in favor of ECMO (35 vs 46%), but this difference failed to reach statistical significance (p = 0.07). They conclude that among patients with severe ARDS, 60-day mortality is not significantly lower with ECMO than with conventional mechanical ventilation strategy including ECMO as rescue therapy.

Authors aknowledge the limitations of the study which needs further validation in RCTs. Whe have to keep in consideration that ECMO improves outcome in case of emergency procedures requiring alternative treatment to improve oxygenation. ECMO also reduce the potentiality of traumatic ventilation in the most severe cases. We can also identify an absolute reduction of mortality of 11% in patients benefiting from early ECMO. Therefore we have to consider theses results with caution before concluding in the absence of the utility of early ECMO therapy in very severe ARDS.

Key points

Systematic ECMO in very severe ARDS is not harmful in the early phase
ECMO improves outcome and in particullar mechanical ventilation invasiveness
Even in this study we cannot avoid the potentiall benefit in the early intervention group because of several limitations
Early ECMO is associated with more bleeding risk, severe thrombocytopenia but less ischemic stroke.