High Yield Intraoperative, Autologous Platelet Apheresis

The overall aim is to reduce overall allogeneic transfusion requirements during cardiac surgery when compared to standard management. To evaluate this the investigators will test the hypothesis that intraoperative, autologous platelet apheresis will primarily avoid allogeneic platelet transfusion. Following induction of anesthesia and intravascular line insertion, the patient will be randomized to control or treatment arms by sealed envelope technique where computer generated, randomization numbers are assigned prior to enrollment based on study patient number which is never reused. The control arm will have central venous access "sham" connected to the apheresis machine Trima® (Terumo BCT, Denver CO); the treatment arm will be connected and undergo pheresis. The clinical team will be blinded by a sterile sheet acting as a curtain and a recorded playback of the typical sounds of the operation of the apheresis machine. At the end of the pheresis, the platelet units will be disguised with opaque coverings and agitated at room temperature in compliance with the American Association of Blood Banks (AABB) recommendations for platelet storage. On separation from CPB, the blinded administration of autologous platelets or allogeneic (blood bank) platelets will occur after protamine administration, if the surgeon requests platelet transfusion (this is typically the case for these operations). The surgeon will be blinded and he will order subsequent transfusions based on clinical evidence of microvascular bleeding in accordance with standard guidelines, as is the investigators practice for these operations.