Transfusion Indications and Reactions

Abstract Understanding both the indications for blood product transfusion and the potential complications is crucial to the knowledge base of an anesthesiologist. In the setting of anemia, the available evidence generally supports transfusion of packed red blood cells (pRBCs) when a patient’s hemoglobin level is between 7 and 10 g/dL depending on the patient’s comorbid conditions, the potential for ongoing blood loss, and signs or symptoms of organ ischemia. Transfusion of fresh frozen plasma and/or platelets is generally indicated in the setting of bleeding attributable to an inherited or acquired deficiency in these factors. Similarly, cryoprecipitate is indicated for bleeding due to hypofibrinogenemia or dysfibrogenemias. Transfusion-related complications vary in severity on the spectrum from symptomatically mild to severe and fatal. The most common complications are relatively benign and include febrile nonhemolytic transfusion reactions (0.5%–1% of all transfusions) and urticarial reactions. More severe reactions are fortunately less common and include anaphylactic reactions (most commonly due to a recipient with immunoglobulin [Ig] A deficiency who receives a blood transfusion containing IgA) and acute hemolytic transfusion reactions (due to transfusion of ABO-incompatible blood most commonly due to clerical error). The risk of transmission of bloodborne pathogens has decreased due to improved testing of the donor blood supply; however, bacterial contamination, especially of platelets (due to their storage at room temperature, which is optimal for bacterial growth), may still occur. Transfusion-related acute lung injury (TRALI) is an illness like acute respiratory distress syndrome (ARDS) appearing within 6 hours of receiving a blood transfusion and is the most common cause of death attributable to blood transfusion. Metabolic derangements, including acidemia, hyperkalemia, and hypocalcemia, are more commonly associated with transfusion of large volumes of blood products.