Etiologic factors in neuropsychiatric complications associated with cardiopulmonary bypass

A prospective study of 204 patients undergoing operations requiring cardiopulmonary bypass was undertaken to determine the incidence and etiologic factors leading to postperfusion cerebral dysfunction and to determine whether pretreatment with thiopental, 15 mg/kg, would reduce the incidence. Patients were randomly assigned to a control (diazepam) or study (thiopental) group and were treated identically except for the drug administered. Patients were examined neurologically on the 1st and 4th postoperative day and a psychometric test was administered on the 4th day. Although fewer neuropsychiatric complications were present in patients given thiopental, the difference was not significant. The overall incidence of cerebral dysfunction attributable to cardiopulmonary bypass alone was 16.2% for transient and 6.4% for persistent dysfunction (present at the 10th postoperative day). The incidence of postoperative cerebral dysfunction was more than twice as high in patients undergoing intracardiac than in patients having extracardiac operations and more than 4 times as high in patients more than 60 years of age than in younger patients. Perfusion pressure less than 50 torr with hematocrit less than 30% was not related to development of postoperative cerebral dysfunction. The data suggest that air or particulate emboli originating within the heart or aorta are the major causes of postbypass cerebral dysfunction.