For many decades, the decision to transfuse red blood cells was based upon the "10/30 rule": transfusion was used to maintain a blood hemoglobin (Hgb) 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 re-examination 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 . During the subsequent 25 years, a large body of clinical evidence was generated, resulting in the publication of many guidelines for red cell transfusion in different settings [3-9]. A common theme of these guidelines is the need to balance the benefit of treating anemia with the desire to avoid unnecessary transfusion, with its associated costs and potential harms. This requires considerable diagnostic skill and acumen on the part of physicians ordering transfusions. At this time, laboratory and diagnostic tests have not demonstrated sufficient precision for providing data on which to base red cell transfusion decisions.
As blood transfusion practices are evaluated in randomized trials, we are increasingly able to emphasize clinical trial data, since these data provide the best evidence to guide transfusion decisions.
The indications and thresholds for red cell transfusion in adults will be reviewed here. General aspects of red cell collection, storage, safety, and administration, as well as practices for some special populations, are presented separately.
●(See "Red blood cell transfusion in adults: Storage, specialized modifications, and infusion parameters".)
●(See "Laboratory testing of donated blood".)