Understanding and managing anemia in critically ill patients

Although anemia is apparently tolerated in most patients, particularly those who are relatively healthy, the ICU population must be thought of differently. Anemia in the ICU may be due to acute blood loss, phlebotomy, or to the presence of inflammatory disease. The anemia in critically ill patients resembles anemia of chronic disease, which is believed to result from a poor endogenous erythropoietin response or erythropoietin deficiency. The risks of blood transfusions are many and ICU patients may not tolerate infusions of older, stored blood. Nonetheless, hemoglobin levels at or above 100 g/L may be important for oxygen delivery to vital organs, especially in critically ill patients with increased oxygen demands. The appropriate transfusion trigger for critically ill patients in this setting remains unknown. Blood transfusions in the ICU may not improve outcomes, and numerous studies have been published to suggest the contrary, that transfusions may actually worsen patients' outcomes in certain ICU settings. Recombinant human erythropoietin (rHuEPO, epoetin alfa) has been shown to reduce transfusion needs and increase hemoglobin levels in multiple settings and now, it appears to also do so in the ICU.