Abstract
Approximately 11 million units of red cells are transfused annually in the United States, making red-cell transfusion one of the most common medical interventions. Red cells are typically administered as a concentrate, called packed red cells, with a preservative solution (hematocrit, 60%) that allows up to 42 days of refrigerated storage. On average, transfusion of 1 unit of red cells, which has a volume of 350 ml, results in a hemoglobin increment of 1 g per deciliter in an adult with stable blood volume.
In this review, we describe the evidence underlying current transfusion guidelines, trends in use, the infectious and noninfectious risks of transfusion, and ongoing research. We describe the effects of transfusion in adults who have cardiovascular disease or gastrointestinal bleeding, who are critically ill, or who are undergoing orthopedic surgery, as well as the effects in children. Discussions of the safety of transfusion in resource-poor countries and the efficacy of transfusion in premature infants, pregnant women, and patients with hemorrhagic shock or congenital anemias are beyond the scope of this review.