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Intraoperative physiologic variables and outcome in cardiac surgery: Part I. In-hospital mortality
S E Hill1, G K van Wermeskerken, J W Lardenoye
1Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710, USA. hill0012@mc.duke.edu
Insights
Coronary artery bypass grafting (CABG) mortality is predicted by preoperative risk, not intraoperative factors like blood pressure or glucose. Preexisting hypertension independently predicts mortality after CABG.
Area of Science:
- Cardiovascular Surgery
- Anesthesiology
- Critical Care Medicine
Background:
- Existing risk stratification for coronary artery bypass grafting (CABG) relies on unalterable preoperative patient factors.
- The impact of intraoperative physiological parameters on CABG outcomes requires further investigation.
Purpose of the Study:
- To assess the influence of intraoperative hematocrit, glucose, mean arterial pressure, and bypass duration on risk-adjusted in-hospital mortality after CABG.
Main Methods:
- Utilized outcome data from 2,862 CABG patients, merged with intraoperative physiological data.
- Calculated a preoperative mortality risk index for each patient.
- Employed univariate and multiple variable logistic regression to identify predictors of mortality.
Main Results:
- Overall in-hospital mortality was 1.85%.
- The preoperative risk index was a significant predictor of mortality (p=0.0001).
- No significant association was found between mortality and intraoperative variables (hematocrit, glucose, mean arterial pressure, bypass duration).
- Preexisting hypertension emerged as an independent predictor of mortality.
Conclusions:
- Preexisting hypertension is an independent predictor of in-hospital mortality in CABG patients.
- Intraoperative factors such as mean arterial pressure < 50 mm Hg, lower hematocrit, or elevated glucose during bypass did not significantly increase mortality risk.
Background:
Risk stratification schemes have been developed to predict outcome of coronary artery bypass grafting (CABG) procedures, which are predominately based upon unalterable preoperative patient characteristics. The purpose of this study was to determine if minimum intraoperative hematocrit, maximum glucose concentration, mean arterial pressure on cardiopulmonary bypass, or duration of bypass influence risk-adjusted in-hospital mortality after CABG.
Methods:
Outcome data from 2,862 CABG patients were merged with intraoperative physiologic data. A preoperative mortality risk index was calculated for each patient. Variables found significant (p<0.05) by univariate logistic regression were tested in a multiple variable model to determine risk-adjusted association with mortality.
Results:
Overall mortality rate was 1.85%. The preoperative risk index was significantly associated with mortality (p = 0.0001). No significant association was present between mortality and intraoperative variables. Preexisting 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 support the hypothesis that mean arterial pressure less than 50 mm Hg, lower hematocrit, or elevated glucose while on bypass increases in-hospital mortality.