Predictive risk factors for delayed extubation in patients undergoing coronary artery bypass grafting.

Abstract

Prolonged mechanical ventilation increases hospitalization costs, airway and lung trauma, and stress. The objective of this study was to elucidate patient characteristics and operative variables that predict delayed extubation in patients undergoing coronary artery bypass grafting (CABG). The records of 167 patients who underwent CABG between 1994 and 1998 were examined retrospectively. The patients were divided into early and delayed extubation groups. Putative factors affecting the duration of intubation were included in a univariate analysis using the t-test and chi-squared test. A logistic regression model was then developed to determine the factors associated with delayed extubation. Forty-four percent of the patients needed prolonged mechanical ventilation (more than 24h). Univariate predictors of delayed extubation (P < 0.05) were emergency surgery, preoperative use of an intra-aortic balloon pump (IABP), the duration of anesthesia, surgery, cardiopulmonary bypass and aortic cross-clamping, the total volume of fentanyl. lowest rectal temperature, glucose level, perioperative transfusion, bleeding, perioperative heart failure, perioperative insertion of IABP, postoperative transfusion, cardiac index, inspired oxygen fraction (FiO2), arterial oxygen tension (PaO2), the PaO2/FiO2 ratio, and the volume of catecholamine. In the delayed extubation group, the intensive care unit stay was significantly longer (P < 0.001) and re-exploration was required more frequently (P = 0.004). Excellent prediction was provided by a model consisting of six variables: age, duration of surgery, perioperative heart failure, glucose level, postoperative transfusion, and the PaO2/FiO2 ratio. These results suggest that decreasing the cardiopulmonary bypass time, maintaining a low glucose level during cardiopulmonary bypass, and ensuring adequate perioperative hemostasis may help to avoid pulmonary dysfunction and delayed extubation. Moreover, the PaO2/FiO2 ratio may be a useful predictor of delayed extubation in patients undergoing CABG.