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Blood transfusion became practical early in the twentieth century with the discovery of blood group antigens and methods for typing and matching donor to recipient. Subsequently, with the development of fortified anticoagulants to improve red blood cell preservation, the biocompatible plastic bag system that allows blood fractionation, and expanded testing to prevent disease transmission, modern concepts of blood component therapy gradually evolved. Transfusion practice is now a complex therapeutic discipline, requiring all the skills of a trained clinician. The transfusion of a blood component can never be taken lightly; it should only be given for a good reason after careful evaluation of the clinical situation.
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Transfusions should always be targeted to the clinical problem, whether blood loss, anemia, or both; thrombocytopenia; or a coagulopathy. Only the most appropriate blood component(s) should be ordered and transfused (Table 38-1). It is also essential to take into account any special needs of the patient, for example, as in the immunosuppressed patient who should receive only irradiated products to avoid transfusion-associated graft-versus-host disease (TA-GVHD). Great care must be taken to prevent mistakes in matching donor product to recipient, and also in recognizing and treating transfusion reactions. All these items are the responsibility of the physicians and nurses involved in the patient's care.
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The practice of whole blood transfusion has largely been replaced by component therapy. However, some blood centers are able to offer whole blood or "modified" whole blood (whole blood minus the platelet component) for the treatment of large-volume blood loss. Its use can save time, cost less, and expose the recipient to fewer donors. In the patient with massive blood loss, transfusion of modified whole blood sustains coagulation factor levels in plasma, but platelets need to be replaced separately. There is increasing evidence that in the setting of massive hemorrhage or trauma, component transfusions that simulate the infusion of whole blood (ie, 1 U of plasma for each unit of red blood cells) leads to better outcome with regard to morbidity and mortality.
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Transfusion of red blood cells is used to treat most anemia, regardless of cause, to improve oxygen delivery to tissues. A single unit of red blood cells contains all of the red blood cells from a 450-mL unit of whole blood (~200 mL of red blood cells) suspended in 130 mL of plasma/acid citrate dextrose (ACD) solution to give a hematocrit of about 60%. A red blood cell unit ...