Efficacy of allogeneic red blood cell transfusions

The majority of intensive care unit (ICU) patients will receive a blood transfusion at some point during the course of their ICU stay, generally in an attempt to increase oxygen delivery and hence tissue oxygenation. The efficacy of red blood cell (RBC) transfusion can be evaluated through its effects on patient mortality or morbidity, or more simply by its effects on tissue oxygenation. Review of the available literature shows controversial results, with some studies showing that RBC transfusion may be efficacious while others do not. The true challenge lies in determining which patients will benefit from transfusion and those in whom it may be safe to delay or withhold transfusion. In this article, several key factors influencing the systemic and regional efficacy of blood transfusion will be reviewed.