For many decades, the decision to transfuse red blood cells was based upon the "10/30 rule": transfusion was indicated in all patients in order to maintain a blood hemoglobin concentration above 10 g/dL (100 g/L) and a hematocrit above 30 percent . However, concern regarding transmission of blood-borne pathogens and efforts at cost containment caused a reexamination of transfusion practices in the 1980s. The 1988 National Institutes of Health Consensus Conference on Perioperative Red Blood Cell Transfusions suggested that no single criterion should be used as an indication for red cell component therapy and that multiple factors related to the patient's clinical status and oxygen delivery needs should be considered . Accordingly, the decision to transfuse erythrocytes must be based upon an assessment of the risks of anemia versus the risks of transfusion [2-4].
The indications for red cell transfusion will be reviewed here. General aspects of red cell collection, storage, and safety as well as the use of massive blood transfusion and blood salvage procedures are discussed separately. (See "Use of red blood cells for transfusion" and "Laboratory testing of donated blood" and "Massive blood transfusion" and "Intraoperative and postoperative blood salvage".)
Preoperative autologous donation of red cells is also discussed separately. (See "Preoperative autologous blood donation" and "Controversial areas in preoperative autologous blood donation".)
Use of massive amounts of blood as well as the use of blood in the critically ill are discussed separately. (See "Massive blood transfusion" and "Use of blood products in the critically ill".)
PHYSIOLOGY OF ANEMIA
The major physiologic considerations relevant to anemic patients are the degree to which oxygen delivery to the tissues is adequate and compensatory mechanisms for maintaining oxygen delivery will not become overwhelmed or deleterious . (See "Oxygen delivery and consumption".) Oxygen delivery (DO2) is determined by the formula: