Objective: To review the literature on the appropriateness of red blood cell transfusion and current physician practice, with emphasis on the physiologic and symptomatic implications of elective transfusion in the treatment of anemia.
Data sources: Studies on the therapeutic use of red blood cell transfusion were identified through a search of MEDLINE (1966 to the present) and through a manual review of bibliographies of identified articles. In addition, evidence was solicited from selected experts in the field and recent consensus panels that have developed transfusion guidelines.
Data synthesis: No controlled trials of blood transfusion were identified, but data were available on four issues relevant to transfusion practice: current physician practice and evidence for excessive use of red blood cell transfusion; physiologic adaptation to anemia; human tolerance of low hemoglobin levels; and strategies for reducing homologous transfusion requirements.
Conclusions: Despite the recent decline in red blood cell use because of concerns about infection, current transfusion practice remains variable because physicians have disparate views about its appropriateness. The remarkable human tolerance of anemia suggests that clinicians can accept hemoglobin levels above 70 g/L (7 g/dL) in most patients with self-limited anemia. In patients with impaired cardiovascular status or with anemias that will not resolve spontaneously, however, the data are insufficient to determine minimum acceptable hemoglobin levels, and therapy must be guided by the clinical situation. Several therapeutic strategies and pharmacologic interventions are available in the perioperative and non-operative settings to further reduce red blood cell use.