- Whole Blood Transfusion
- Red Blood Cell Transfusion
- Autologous Transfusion
- Red Cell Exchange
- Platelet Transfusion
- Transfusion of Plasma Components
Indicated when acute blood loss is sufficient to produce hypovolemia, whole blood provides both oxygen-carrying capacity and volume expansion. In acute blood loss, hematocrit may not accurately reflect degree of blood loss for 48 h until fluid shifts occur.
Indicated for symptomatic anemia unresponsive to specific therapy or requiring urgent correction. Packed red blood cell (RBC) transfusions may be indicated in pts who are symptomatic from cardiovascular or pulmonary disease when Hb is between 70 and 90 g/L (7 and 9 g/dL). Transfusion is usually necessary when Hb is <70 g/L (<7 g/dL). One unit of packed RBCs raises the Hb by ∼10 g/L (1 g/dL). In the setting of acute hemorrhage, packed RBCs, fresh frozen plasma (FFP), and platelets in an approximate ratio of 3:1:10 units are an adequate replacement for whole blood. Removal of leukocytes reduces risk of alloimmunization and transmission of cytomegalovirus. Washing to remove donor plasma reduces risk of allergic reactions. Irradiation prevents graft-versus-host disease in immunocompromised recipients by killing alloreactive donor lymphocytes. Avoid related donors.
Other Indications
(1) Hypertransfusion therapy to block production of defective cells, e.g., thalassemia, sickle cell anemia; (2) exchange transfusion-hemolytic disease of newborn, sickle cell crisis; (3) transplant recipients-decreases rejection of cadaveric kidney transplants.
Complications
(1) Transfusion reaction-immediate or delayed, seen in 1-4% of transfusions; IgA-deficient pts at particular risk for severe reaction; (2) infection-bacterial (rare); hepatitis C, <0.1-1 in 1,000,000 transfusions; HIV transmission, 0.1-1 in 1,000,000; (3) circulatory overload; (4) iron overload-each unit contains 200- to 250-mg iron; hemochromatosis may develop after 100 U of RBCs (less in children), in absence of blood loss; iron chelation therapy with deferoxamine indicated for ferritin >1000 ng/mL; (5) graft-versus-host disease; (6) alloimmunization (Table 9-1 Risks of Transfusion Complications).
Use of pt's own stored blood avoids hazards of donor blood; also useful in pts with multiple RBC antibodies. Pace of autologous donation may be accelerated using erythropoietin (50-150 U/kg SC three times a week) in the setting of normal iron stores.
The main goal of red cell exchange transfusions is to remove sickle cells and replace them with normal red cells to interrupt the vicious cycle of sickling, stasis, vasoocclusion, and hypoxemia that propagate sickle cell crises. The usual target is 70% hemoglobin A.
Prophylactic transfusions are usually reserved for platelet count <10,000/µL (<20,000/µL in acute leukemia). One unit elevates the count by about 10,000/µL if no platelet antibodies are present as a result of prior transfusions. Efficacy assessed by 1- and 24-h posttransfusion platelet counts. HLA-matched single-donor platelets may be required in pts with platelet alloantibodies.
Transfusion of Plasma Components 
FFP is a source of coagulation factors, fibrinogen, antithrombin, and proteins C and S. It is used to correct coagulation factor deficiencies, rapidly reverse warfarin effects, and treat thrombotic thrombocytopenic purpura (TTP). Cryoprecipitate is a source of fibrinogen, factor VIII, and von Willebrand factor; it may be used when recombinant factor VIII or factor VIII concentrates are not available.