Transfusion trigger: when to transfuse?

The decision to transfuse a hospitalized patient must balance the known risks of transfusion with the need to provide adequate tissue oxygenation and the appropriate utilization of blood as a scarce resource. The minimum tolerated hemoglobin level is not well established, and considerable variation exists in intensivists' transfusion practices. Conventional transfusion triggers of 100 g/l have been challenged by reports indicating that aerobic metabolism is supported by hemoglobin levels of 50 g/l or less. Evidence from randomized trials also indicates that withholding transfusions may result in improved outcomes. Arbitrary numeric hemoglobin triggers, however, cannot supercede intervention based on individual physiologic need and clinical circumstances.