Anesthesiology 1999; 91:936 – 44 © 1999 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Risk Factors of Delayed Extubation, Prolonged Length of Stay in the Intensive Care Unit, and Mortality in Patients Undergoing Coronary Artery Bypass Graft with Fast-track Cardiac Anesthesia A New Cardiac Risk Score David T. Wong, M.D.,* Davy C. H. Cheng, M.D., Rafal Kustra, M.Sc.,‡ Robert Tibshirani, Ph.D.,§ Jacek Karski, M.D.,* Jo Carroll-Munro, R.N.,i Alan Sandler, M.D.# Background: Risk factors of delayed extubation, prolonged intensive care unit (ICU) length of stay (LOS), and mortality have not been studied for patients administered fast-track car- diac anesthesia (FTCA). The authors’ goals were to determine risk factors of outcomes and cardiac risk scores (CRS) for CABG patients undergoing FTCA. Methods: Consecutive CABG patients undergoing FTCA were prospectively studied. Outcome variables were delayed extuba- tion > 10 h, prolonged ICU LOS > 48 h, and mortality. Univar- iate analyses were performed followed by multiple logistic re- gression to derive risk factors of the three outcomes. Simplified integer-based CRS were derived from logistic models. Bootstrap validation was performed to assess and compare the predictive abilities of CRS and logistic models for the three outcomes. Results: The authors studied 885 patients. Twenty-five percent had delayed extubation, 17% had prolonged ICU LOS, and 2.6% died. Risk factors of delayed extubation were increased age, female gender, postoperative use of intraaortic balloon pump, inotropes, bleeding, and atrial arrhythmia. Risk factors of prolonged ICU LOS were those of delayed extubation plus preoperative myocardial infarction and postoperative renal insufficiency. Risk factors of mortality were female gender, emergency surgery, and poor left ventricular function. CRSs were modeled for the three outcomes. The area under the receiver operating characteristic curve for the CRS–logistic models was not significantly different: 0.707/0.702 for delayed extubation, 0.851/0.855 for prolonged ICU LOS, and 0.657/0.699 for mortality. Conclusion: In CABG patients undergoing FTCA, the authors derived and validated risk factors of delayed extubation, pro- longed ICU LOS, and mortality. Furthermore, they developed a simplified CRS system with similar predictive abilities as the logistic models. (Key words: Coronary artery bypass graft; fast- track cardiac anesthesia; outcome; predictors; risk score.) CORONARY artery bypass graft (CABG) surgery is one of the most expensive major surgical procedures in North America. There were 20,649 CABG surgeries performed in Canada in 1991 and an estimated 485,000 in the United States in 1993. 1,2 With constraints in health care resources and increasing demand for services, providers need to contain costs in CABG surgery. Cardiac surgical patients also want to know the risks involved, and phy- sicians need outcome data for quality assurance. Predic- tive models for mortality, morbidity, and intensive care unit (ICU) length of stay (LOS) have been developed for This article is accompanied by an Editorial View. Please see: London MJ, Shroyer ALW, Grover FL: Fast tracking into the new millenium: An evolving paradigm. ANESTHESIOLOGY 1999; 91:911– 4. r * Assistant Professor, Department of Anesthesia, University Health Network. Associate Professor, Department of Anesthesia, University Health Network. ‡ Graduate Student, Department of Public Health Sciences, Univer- sity of Toronto. § Professor, Department of Public Health Sciences, University of Toronto. i Research Nurse Coordinator, Department of Anesthesia, University Health Network. #Professor, Department of Anesthesia, University Health Network. Received from the Divisions of Cardiac Anesthesia and Intensive Care, Department of Anesthesia, University Health Network; and the Department of Public Health Sciences, University of Toronto, Toronto, Ontario, Canada. Submitted for publication August 14, 1998. Accepted for publication May 18, 1999. Supported in part by the Department of Anesthesia, Toronto General Hospital, University Health Network, Uni- versity of Toronto. Presented in part at the annual meetings of the Society of Cardiovascular Anesthesiologists, Baltimore, Maryland, May 10, 1997, and Canadian Anaesthetists’ Society, Vancouver, British Co- lumbia, Canada, June 6, 1997. Address reprint requests to Dr. Cheng: Department of Anesthesia, Toronto General Hospital, 585 University Avenue, BW 4-646, To- ronto, Ontario, Canada M5G 2C4. Address electronic mail to: dcheng@torhosp.toronto.on.ca 936 Anesthesiology, V 91, No 4, Oct 1999 Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/91/4/936/397784/0000542-199910000-00012.pdf by guest on 20 March 2022