Blood product transfusions on extracorporeal membrane oxygenation: a narrative review

Background and Objective: Extracorporeal membrane oxygenation (ECMO) remains amongst the most invasive measures to treat organ dysfunctions, such as refractory cardiogenic shock and/or respiratory failure, in many cases being considered a last resort. Hemodilution, hemolysis and coagulation disorders are very common during ECMO therapy, necessitating blood and blood products transfusions virtually in every patient undergoing ECMO. There exist no randomized data on blood product transfusion protocols in the ECMO population. The only evidence comes from observational studies and cardiopulmonary bypass experiences in patients undergoing cardiac surgery which should not be extrapolated to ECMO patients because of substantial differences in circuit composition, support duration, heparinization and access. Methods: The current review attempts to summarize the existing evidence on blood product transfusions in patients undergoing ECMO therapy. We screened PubMed and Google Scholar for all reports on blood product transfusion in ECMO patients up until December 2020. The review summarizes separately available data on red blood cells, platelets, fresh frozen plasma and coagulation factors. Key Content and Findings: There is a significant variability in-between centers regarding hemoglobin or hematocrit threshold for red blood cells transfusion in ECMO patients. Data from observational studies suggest that lower thresholds for red blood cell transfusion may not adversely influence survival while being more cost-effective. A gap in knowledge persists regarding the indications for platelet transfusions with some experienced centers adopting relatively low thresholds in non-bleeding patients. Conclusions: Randomized controlled trials accessing restrictive or liberal strategies in blood product transfusions are necessary. Reported worse prognosis in patients with multiple transfusions should be associated with their worse baseline status rather than transfusions themselves.