Restrictive red blood cell transfusion and alternatives to transfusion in the critically ill: a review of the clinical evidence

Anemia is a common problem in the critically ill. Its causes are multifactorial and include bleeding, iatrogenic blood loss through diagnostic phlebotomy and blunted erythropoiesis. Although red blood cell transfusions are a life-saving therapy in cases of severe anemia and in the acutely bleeding patient, the benefits in cases of mild and moderate anemia are still debated. Several blood conservation strategies may help to reduce blood loss, and hence mitigate against anemia in the critically ill. These strategies include the use of hemoglobin substitutes, hemostatic agents, blood salvage, erythropoietin and preventative strategies to minimize blood loss in the critically ill. This review article highlights and summarizes potential benefits and risks associated with red blood cell transfusion. It also summarizes current clinical evidence for a restrictive red blood cell transfusion strategy in critically ill adults, children and premature infants, and discusses evidence for different red blood cell conservation strategies in the critically ill setting.