Intraoperative physiologic variables and outcome in cardiac surgery: Part I. In-hospital mortality

Background. Risk stratification schemes have been developed to predict outc ome of coronary artery bypass grafting (CABC) procedures, which are predomi nately based upon unalterable preoperative patient characteristics. The pur pose of this study was to determine if minimum intraoperative hematocrit, m aximum glucose concentration, mean arterial pressure on cardiopulmonary byp ass, or duration of bypass influence risk-adjusted in-hospital mortality af ter CABG. Methods. Outcome data from 2,862 CABC patients were merged with intraoperat ive physiologic data. A preoperative mortality risk index was calculated fo r each patient. Variables found significant (p < 0.05) by univariate logist ic regression were tested in a multiple variable model to determine risk-ad justed association with mortality. Results. Overall mortality rate was 1.85%. The preoperative risk index was significantly associated with mortality (p = 0.0001). No significant associ ation was present between mortality and intraoperative variables. Preexisti ng hypertension was an independent predictor of mortality after controlling for risk index and bypass duration. Conclusions. Preexisting hypertension proved to be an independent predictor of mortality in our patient population. This study found no evidence to su pport the hypothesis that mean arterial pressure less than 50 mm Hg, lower hematocrit, or elevated glucose while on bypass increases in-hospital morta lity. (C) 2000 by The Society of Thoracic Surgeons.