Blood Transfusion Issues in the Critically Ill

Anemia is a common clinical problem seen in the critically ill and results in a large RBC transfusion requirement for these patients. The view that RBC transfusion is risk-free is no longer tenable today. There is the accumulating evidence that allogeneic blood transfusion is immunosuppressive. More reently, attention has focused on the age of RBCs transfused. Transfused RBCs, especially during the time period immeditely following transfusion, are not normal. The duration of RBC storage may be an important determinant of the efficacy of RBCs as oxygen carriers as well as a determinant of transusion related morbidity. Adding to the controversy about risk/benefit ratio for RBC transfusion are recent data showing that an aggressive RBC transfusion strategy may decrease the likelihood of survival in selected subpopulations of critically ill adults. The optimal hematocrit for the ICU patient remains to be determined. It seems clear that hemoglobin levels falling significantly below the “10/30” threshold can be tolerated. However, it is not clear that this is applicable to the critically ill ICU patient population. Therefore, while hemoglobin levels in the 7-10 mg/dL range are well tolerated in the “stable” “nontressed” patient, this range might not be optimal for the critcally ill patient. Conservative transfusion thresholds as well as strategies to minimize loss of blood and increase the producion of RBCs are important in the management of critically ill patients.