ABSTRACT
The risk of death from anemia was well characterized in a retrospective cohort study of 1958 patients undergoing surgery who declined blood transfusions for religious reasons. A notable trial evaluated transfusion thresholds in 921 patients with severe upper gastrointestinal bleeding but without massive exsanguination and compared transfusion less than 7 g/dL versus 9 g/dL. There is insufficient evidence to recommend a transfusion threshold in patients with acute coronary syndrome, acute stroke, and other disorders. Acute upper gastrointestinal bleeding is a common cause of anemia in critical care and hospitalized patients. The causes of anemia in hospitalized patients are varied and include active bleeding, post-surgical blood loss, excessive phlebotomy, nutritional deficiencies, the effect of pharmacological therapeutics, or as a result of the underlying illness itself, leading to bone marrow suppression or hemolysis. Patients undergoing cardiac surgery are among the most transfused patients overall and in critical care units.
