Comparison of the effects of transfusions of cryopreserved and liquid-preserved platelets on hemostasis and blood loss after cardiopulmonary bypass

Objective: The aim of the study was to compare the clinical effects and hem ostatic efficiency of transfusions of platelets preserved in the frozen sta te for as long as 2 years with transfusions of platelets preserved in the c onventional manner for as long as 5 days in patients undergoing cardiopulmo nary bypass. Methods: Seventy-three patients were prospectively randomly as signed to receive transfusions of cryopreserved or liquid-preserved platele ts, Nonsurgical blood loss was measured during and after the operation. Ble eding time, hematologic variables, and the bleeding time site shed blood we re assayed before cardiopulmonary bypass and at 30 minutes and 2, 4, and 24 hours after transfusion. In vitro platelet function tests were conducted o n platelets obtained from healthy volunteers. Results: No adverse sequelae of the transfusions were observed, Blood loss and the need for postoperativ e blood product transfusions were lower in the group receiving cryopreserve d platelets, Lower posttransfusion platelet increments and a tendency towar d decreased platelet survival were observed in patients receiving cryoprese rved platelets. Hematocrit and plasma fibrinogen were significantly higher in this group, and the duration of intubation was shorter. In vitro, cryopr eserved platelets demonstrated less aggregation, lower pH, and decreased re sponse to hypotonic stress but generated more procoagulant activity and thr omboxane. Conclusions: (1) Cryopreserved platelet transfusions are superior to liquid-preserved platelets in reducing blood loss and the need for bloo d product transfusions after cardiopulmonary bypass. (2) The reduction in b lood loss in the patients receiving cryopreserved platelet transfusions aft er cardiopulmonary bypass probably reflects improved in vivo hemostatic fun ction of cryopreserved platelets. (3) Some in vitro measures of platelet qu ality (aggregation, pH, hypotonic stress) may not reflect in vivo quality o f platelet transfusions after cardiopulmonary bypass, whereas other in vitr o measures (platelet procoagulant activity and thromboxane) do.