The role of erythropoietin therapy in the critically ill

Critically ill patients receive an extraordinarily large number of blood transfusions. Between 40% and 50% of all patients admitted to intensive care units (ICUs) receive at least one allogeneic red blood cell (RBC) unit and average close to 5 U of RBCs during their ICU admission. RBC transfusion is not risk-free, and there is little evidence that "routine" transfusion of stored allogeneic RBCs is beneficial to critically ill patients. It is clear that most critically ill patients can tolerate hemoglobin levels as low as 7 g/dL, and therefore, a more conservative approach to RBC transfusion is warranted. Anemia of critical illness is a distinct clinical entity characterized by blunted erythropoietin (EPO) production and abnormalities in iron metabolism identical to what is commonly referred to as anemia of chronic disease. As such, the bone marrow in many of these patients responds to the administration of exogenous EPO, in spite of their underlying critical illness. The efficacy of perioperative recombinant human erythropoietin (rHuEPO) has been demonstrated in a variety of elective surgical settings. Similarly, in critically ill patients, rHuEPO therapy will also stimulate erythropoiesis. In randomized placebo-controlled trials, therapy with rHuEPO resulted in a significant reduction in allogeneic RBC transfusions. Strategies to increase the production of RBCs are complementary to other approaches to reduce blood loss in the ICU and decrease the transfusion threshold in the management of all critically ill patients.