Toward Reducing Perioperative Transfusions

With increased knowledge about the components of blood, transfusions are safer than ever. However, a slight risk of disease transmission still exists along with clerical errors leading to ABO mismatching between donors and recipients. Diseases transmitted through blood transfusions include HIV, hepatitis B and C, and bacterial infections. Other risks include donor screening errors, acute lung injury, fatal hemolytic reactions, anaphylactic reactions, and leukocytic target organ injury. Complications, such as acute renal failure, air embolism, anaphylactic reactions, bacterial sepsis, cardiovascular stress, febrile reaction, hypothermia, immunosuppression, and transfusion-associated circulatory overload, can occur. Joyce outlines specific objectives in this course update for nurse anesthetists. The “transfusion trigger,” at which point a transfusion should be given, has been controversial, but current recommendations from the ASA indicate that a transfusion should be given when the patient’s hemoglobin value is <6 g/dL. If a patient’s hemoglobin concentration is ≥10 g/dL, a transfusion is not necessary unless other debilitating conditions exist. The ASA guidelines also offer recommendations for transfusions of platelets, fresh frozen plasma, and cryoprecipitate. Strategies to minimize or prevent transfusions are based on preoperative, intraoperative, and postoperative interventions. Preoperative interventions include altering the patient’s intake of drugs affecting coagulation for 7-10 d before surgery, administering antifibrinolytic agents if warranted, providing erythropoiesis-stimulating agents to increase the patient’s preoperative hemoglobin level, and obtaining a preoperative autologous donation (PAD). Intraoperative measures involve acute normovolemic hemodilution (ANH) by which blood is withdrawn from the patient and stored in transfusion bags immediately before the surgical incision is made; simultaneously, crystalloids or colloids (or both) are infused at a rate to maintain normovolemia. The patient’s own blood, devoid of donor infectious agents, can then be reinfused during surgery or postoperatively. Another measure is to accept lower hemoglobin levels (6-9 g/dL). The choice of anesthetic technique can reduce the need for blood transfusion and controlled hypotension can reduce blood loss, although it should be used only in patients otherwise healthy enough to withstand it. Keeping the patient normothermic is a necessary goal for anesthetists because hypothermia reduces platelet function. Postoperatively, reinfusion of shed blood is a possibility and is particularly adaptable to those Jehovah Witnesses who will not accept blood from other donors. The paradigms for blood transfusion will have to change through education, sound interventions, and lowering of transfusion thresholds to reduce the rate of blood transfusions.