Current status of blood component therapy in surgical critical care

The use of blood component therapy, with transfusion of red cells, plasma, and platelets, is common in critical care. New evidence has emerged documenting the risks associated and lack of efficacy or improvement in clinical outcome with blood transfusion for the treatment of anemia in critically ill patients who are hemodynamically stable.The safety of a restrictive transfusion strategy (transfuse only if hemoglobin < 7 g/dL) was reported in 1999. Despite compelling evidence from this prospective randomized clinical trial, clinicians have not substantially changed practice regarding blood transfusion in critical care. The recently published CRIT trial reported that the mean pre-transfusion hemoglobin was 8.6 g/dL in this large multicenter trial that examined transfusion practices in critical care in the US. Furthermore, only 19% of hospitals had an institutional blood transfusion protocol. The Surviving Sepsis Campaign guidelines have also recommended blood transfusion only when hemoglobin falls to 7.0 g/dL, following resolution of tissue hypoperfusion and in the absence of significant coronary artery disease or acute hemorrhage. We have an increased understanding of the pathophysiology of the anemia associated with critical care, related to the inflammatory response, downregulation of erythropoietin, and lack of iron availability due to macrophage sequestration. Clinical trials are underway to confirm the efficacy of recombinant erythropoietin in the treatment of critically ill patients with anemia.Current data regarding blood transfusion thresholds and risks of blood transfusion have not as yet significantly altered practice patterns. Efforts to reduce blood transfusion rates in critically ill patients are required. These strategies will require education, unit and institutional protocols, and reduction of phlebotomy for diagnostic laboratory testing in the intensive care unit. Further investigations regarding anemia in critical care and new treatment and prevention strategies are required.