Anemia and RBC Transfusion

Marik, Paul Ellis

Anemia is common in critically ill patients. More than 90% of patients have subnormal hemoglobin by the third day of ICU admission. Despite the fact that blood transfusions have not been shown to improve the outcome of ICU patients (see below) and that the current guidelines recommend blood transfusion only when the hemoglobin falls below 7.0 g/dl, almost half of all patients admitted to an ICU receive a blood transfusion.(1,2) The etiology of anemia of critical illness is multi-factorial and complex. Repeated phlebotomy, gastrointestinal blood loss, and other surgical procedures contribute significantly to the development of anemia. Red cell production in critically ill patients is often abnormal and is involved in the development and maintenance of anemia. The pathophysiology of this anemia includes decreased production of erythropoietin (EPO), impaired bone marrow response to erythropoietin, and reduced red cell survival.