Re-evaluating the transfusion trigger: how low is safe?

Concerns about transfusion-associated complications, in particular viral transmission, have motivated a more restrained pattern of clinical transfusion practice. This change in practice has allowed for an evaluation of the risks of withholding transfusion and the benefits of providing transfusion. The recognized risks of transfusion have declined, and this reduction in risks has been brought about by improved screening, better testing strategies and tests, and leuko-reduction at the time of donation. There are benefits to transfusion, in limiting hypoxic morbidity and mortality. These benefits are clearly evident only at very low levels of serum hemoglobin concentrations in healthy patients who tolerate moderate levels of anemia without morbidity. However, the benefits of transfusion are apparent at higher initial serum level concentrations in patients with cardiovascular disease who are less tolerant of anemia.