Intraoperative physiologic variables and outcome in cardiac surgery: Part II. Neurologic outcome

Background. The impact of alterable physiologic variables on neurologic out come after coronary artery bypass grafting procedures is unknown. The purpo se of this study was to determine whether minimum intraoperative hematocrit , maximum glucose concentration, or mean arterial pressure during cardiopul monary bypass influences risk-adjusted neurologic outcome after coronary ar tery bypass grafting. Methods. Outcome data from 2,862 patients undergoing coronary artery bypass grafting were merged with intraoperative physiologic data. A preoperative stroke risk index was calculated for each patient. Variables found signific ant by univariate logistic regression were tested in a multivariable model to determine association with. outcome. Results. The incidence of stroke or coma in the study population was 1.3%. After controlling for stroke risk and bypass time, only an index of low mea n arterial pressure during bypass retained a significant inverse associatio n with outcome (p = 0.0304). Conclusions. This study found no evidence that glucose concentration or min imum hematocrit are associated with major adverse neurologic outcome. The a ssociation between lower pressure during bypass and decreased incidence of stroke or coma persisted in all risk groups. This points to mechanisms othe r than hypoperfusion as the primary cause of neurologic injury associated w ith cardiac surgery. (C) 2000 by The Society of Thoracic Surgeons.