Transfusion practice in the critically ill.

BACKGROUND Anemia in the critically ill patient population is common. This anemia of critical illness is a distinct clinical entity characterized by blunted erythropoietin production and abnormalities in iron metabolism identical to what is commonly referred to as the anemia of chronic disease. FINDINGS As a result of this anemia, critically ill patients receive an extraordinarily large number of blood transfusions. Between 40% and 50% of all patients admitted to intensive care units receive at least one red blood cell unit, and the average is close to five red blood cell units during their intensive care unit stay. There is little evidence that "routine" transfusion of stored allogeneic red blood cells is beneficial for critically ill patients. Most critically ill patients can tolerate hemoglobin levels as low as 7 mg/dL, so a more conservative approach to red blood cell transfusion is warranted. CONCLUSION Practice strategies should be directed toward a reduction of blood loss (phlebotomy) and a decrease in the transfusion threshold in critically ill patients.