early venovenous extracorporeal membrane oxygenation is associated with lower mortality in patients who have severe hypoxemic respiratory failure a retrospective multicenter cohort study purpose the purpose of the study is to compare outcomes in patients who had severe hypoxemic respiratory failure pao2fraction of inspired oxygen 100 who received early venovenous extracorporeal membrane oxygenation ecmo as an adjunct to mechanical ventilation to those in patients who received conventional mechanical ventilation alonematerials and methods this is a multicenter retrospective unmatched and matched cohort study of patients admitted between april 2006 and december 2013 generalized logistic mixedeffects models and cox proportional hazards models were used to determine the association between treatment with ecmo that was started within 3 days of intensive care unit icu admission and icu and hospital mortality and length of stay respectivelyresults a total of 2440 patients who had severe hypoxemic respiratory failure due to various etiologies were included 46 who received early venovenous ecmo and 2394 unmatched and 398 matched controls who received conventional ventilation alone compared to matched controls ecmo was associated with a lower odds of icu odds ratio 95 confidence interval 030 013067 and inhospital death odds ratio 030 014067 in addition ecmo was associated with longer times to discharge from icu and hospital hazard ratio 042 037047 and 053 038073 respectivelyconclusions in this observational study use of early ecmo compared to conventional mechanical ventilation alone in patients who had severe hypoxemic respiratory failure was associated with a lower risk of mortality and a longer length of stay