BLOOD TRANSFUSION

Blood Transfusion

Blood Transfusion

Blood Transfusion

Blood transfusion can be a lifesaving procedure, but it has risks, including infectious and noninfectious complications. There is debate in the medical literature concerning the appropriate use of blood and blood products. Clinical trials investigating their use suggest that waiting to transfuse at lower hemoglobin levels is beneficial. This review will consider the indications for transfusion of blood and blood products, and will discuss common noninfectious complications associated with transfusion.

Red Blood Cells

Packed red blood cells (RBCs) are prepared from whole blood by removing approximately 250 mL of plasma. One unit of packed RBCs should increase levels of hemoglobin by 1 g per dL (10 g per L) and hematocrit by 3 percent. In most areas, packed RBC units are filtered to reduce leukocytes before storage, which limits febrile nonhemolytic transfusion reactions (FNHTRs), and are considered cytomegalovirus safe. RBC transfusions are used to treat hemorrhage and to improve oxygen delivery to tissues. Transfusion of RBCs should be based on the patient's clinical condition. Indications for RBC transfusion include acute sickle cell crisis (for stroke prevention), or acute blood loss of greater than 1,500 mL or 30 percent of blood volume. Patients with symptomatic anemia should be transfused if they cannot function without treating the anemia. Symptoms of anemia may include fatigue, weakness, dizziness, reduced exercise tolerance, shortness of breath, changes in mental status, muscle cramps, and angina or severe congestive heart failure. The 10/30 rule—transfusion when a patient has a hemoglobin level less than or equal to 10 g per dL (100 g per L) and a hematocrit level less than or equal to 30 percent—was used until the 1980s as the trigger to transfuse, regardless of the patient's clinical presentation (Engelfriet, Brand, 2006).

In 1999, a randomized, multicenter, controlled clinical trial evaluated a restrictive transfusion trigger (hemoglobin level of 7 to 9 g per dL [70 to 90 g per L]) versus a liberal transfusion trigger (hemoglobin level of 10 to 12 g per dL [100 to 120 g per L]) in patients who were critically ill.1 Restrictive transfusion practices resulted in a 54 percent relative decrease in the number of units transfused and a reduction in the 30-day mortality rate. The authors recommended transfusion when hemoglobin is less than 7 g per dL, and maintenance of a hemoglobin level between 7 to 9 g per dL. A recently updated Cochrane review supports the use of restrictive transfusion triggers in patients who do not have cardiac disease (Popovsky, 2002).

A similar study was carried out in critically ill children. The restrictive transfusion trigger was a hemoglobin level of 7 g per dL, with a target level of 8.5 to 9.5 g per dL (85 to 95 g per L). The liberal transfusion trigger was a hemoglobin level of 9.5 g per dL, with a target level of 11 to 12 g per dL (110 to 120 g per L). Patients in the restrictive group received 44 percent fewer blood transfusions, with no difference in rates ...