Red blood cell transfusion in veno-arterial extracorporeal membrane oxygenation - the disconnect between oxygen delivery and tissue oxygenation.

BackgroundRed cell transufion in veno-arterial membrane oxygenation (VA ECMO) has been widely debated.PurposeThis narrative review aims to examine the historical and current approaches of red cell transfusion in veno-arterial extracorporeal membrane oxygenation (VA ECMO) to enhance oxygen delivery. It will explore the potential benefits and pitfalls of red blood cell (RBC) transfusion in VA ECMO, including relationship between haemoglobin (Hb) concentration, tissue oxygenation and patient outcomes associated with transfusion. Following it will review the impact of cardiogenic shock on the microcirculation, performance of transfused RBC and effects of the ECMO circuit on RBC function. It will conclude with an introduction to potential mechanisms by which we might manipulate red cells to improve tissue oxygenation, without augmentation of Hb concentration.ConclusionFurther research is needed to provide insight into optimal RBC transfusion thresholds and strategies to augment red cell function to optimise tissue oxygenation in VA ECMO.