Platelet dysfunction associated with cardiopulmonary bypass.

The clinical significance and pathogenesis of the platelet dysfunction following cardiopulmonary bypass were studied in conjunction with the degree of functional impairment associated with the use of membrane and bubble oxygenators. Forty consecutive patients had the following tests preoperatively and postoperatively: complete blood count (CBC), platelet count, prothrombin consumption time, bleeding time, prothrombin time, partial thromboplastin time, fibrinogen, euglobulin clot lysis, fibrin degradation products, and platelet aggregation tests. Six patients were given 14C-serotonin tests before and after operation, and preoperative and postoperative electron micrographs were made of the platelets of 3 patients. The amount of blood lost, the blood transfused, and plasma hemoglobin levels were also measured. Abnormal aggregation of platelets was found, with no difference between the membrane and bubble oxygenators. In vitro aggregation tests with protamine sulfate and hemoglobin solutions, as well as the 14C-serotonin studies and electron micrographs, suggest that platelets acquire storage pool deficiency and an abnormal membrane during cardiopulmonary bypass.