How do we forecast tomorrow's transfusion? - Next generation transfusion practices to improve recipient safety.

Recipient safety measures play a key role in overall transfusion efficacy. The key advances in safety over the first century of transfusion medicine have been the development of techniques to prevent hemolytic transfusion reactions, hemolytic disease of the newborn and transmission of viral pathogens. While these risks remain important, they affect many fewer patients than previously. We propose that some of the most important current safety issues relate to toxicities broadly encompassed by the immunomodulatory effects of allogeneic transfusion. These include (1) universal leukoreduction to mitigate nosocomial infections, inflammation and organ injury, (2) removal of stored supernatant and its attendant toxic contents that cause dysfunctional immunity and organ injury, (3) avoiding infusing ABO incompatible antigen and antibody that can lead to bleeding, platelet refractoriness and inflammation, (3) minimizing prophylactic transfusions (particularly of plasma and platelets) except where benefit is proven, and (4) avoiding use of normal saline which is linked to renal failure and possibly hemolysis. Accompanying these safety measures will be the continued growth of one of the most important safety measures, patient blood management, which has as one benefit the avoidance of unnecessary and harmful transfusions. Reducing the toxicity of transfusions will enhance the improved clinical outcomes seen with patient blood management.

Optimizing platelet transfusion therapy.

Platelet transfusions are widely used. Prophylactic transfusions are employed in severely thrombocytopenic patients without evidence of bleeding, but no randomized trial data prove the safety or efficacy of this approach. Randomized trials have demonstrated the equivalence of transfusion triggers of 10,000 and 20,000/microl for prophylactic transfusions. The former threshold is potentially safer for the patient, conservative of donor resources and leads to lower costs, with perhaps a slightly greater risk of minor hemorrhage. Randomized trials have demonstrated the equivalence of pheresis or whole blood-derived platelet transfusions. The former present a lower risk for infectious agents, and the latter are less expensive and a more efficient use of limited donor resources. Randomized trials prove that leukoreduced and ABO identical platelet transfusions reduce the risks of HLA alloimmunization and platelet transfusion refractoriness (both leukoreduction and ABO matching), transfusion reactions (leukoreduction) and CMV transmission (leukoreduction). Leukoreduction and ABO matching of platelet transfusions also have been associated in preliminary observational studies with reduced morbidity and mortality in surgical patients and reduced infections in patients with leukemia. These results require further investigation. Future challenges include (1) determining the best approach to bacterial contamination of platelets, whether by detection methods or pathogen inactivation and (2) determining the threshold for prophylactic platelet transfusions in thrombocytopenic patients undergoing surgery or invasive procedures.