Objective: To review studies that have evaluated the effects of liberal or restrictive red cell transfusion thresholds on clinical outcomes in patients requiring extracorporeal membrane oxygenation (ECMO) support for cardiac or respiratory failure.
Design: A systematic review and meta-analysis.
Setting and participants: The study comprised 1,070 patients from observational studies and randomized controlled trials analyzing transfusion policies in venoarterial (VA) and venovenous (VV) ECMO adult populations.
Measurements and main results: Eligible studies were identified by searching the Cochrane Central Register of Controlled Trials, Medline, and EMBASE until March 4, 2020, using a combination of subject headings and text words. Risk of bias assessment was performed to assess study quality according to the ROBINS-I tool and the case series studies appraisal checklist. There was high risk of bias in the studies analyzed, and none had methodologic adequacy. Three studies analyzed VA ECMO and VV ECMO patients separately. Five datasets were related exclusively or mostly to VA ECMO. Four were retrospective analyses, and one was conducted as a prospective observational study; the median transfusion threshold reported was 8 g/dL, with a mean mortality of 52%. Eight datasets were related either exclusively or mostly to VV ECMO. Six were retrospective and two were prospective observational studies; the median transfusion threshold was 8 g/dL, and the mean mortality rate was 33%.
Conclusions: The present study did not resolve uncertainty as to transfusion management in ECMO, although several studies (most of them in VV ECMO) demonstrated that a restrictive threshold has acceptable outcomes in single-center cohorts.
Keywords: acute respiratory distress syndrome; blood transfusion; cardiogenic shock; extracorporeal membrane oxygenation.
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