ABSTRACT
Objective:To identify the risk factors for postoperative delirium (POD) in frail elderly patients undergoing cardiac surgery and develop a ROC prediction model.Methods:The medical records of patients of either sex, aged ≥65 yr, of American Society of Anesthesiologists Physical Status classification Ⅲ or Ⅳ, with frailty index score>0.25, underwent open heart surgery under cardiopulmonary bypass (CPB) from January 2022 to June 2022, were collected retrospectively.The patients were divided into POD group and non-POD group according to POD occurred within 7 days after operation.Clinical information such as gender, age, Mini-mental State Examination score, past medical history, results of the laboratory test before surgery, operation time, cerebral oxygen saturation (rSO 2), rSO 2 baseline (rSO 2 baseline), lowest intraoperative rSO 2 value before, during and after CPB (CPB 1rSO 2 lowest, CPB 2rSO 2 lowest, CPB 3rSO 2 lowest) , the greatest decrease in intraoperative rSO 2 from the baseline value before, during and after CPB (CPB 1rSO 2 decrease, CPB 2rSO 2 decrease, CPB 3rSO 2 decrease) were recorded.Multivariate logistic regression analysis was used to identify the risk factors for POD, and the receiver operating characteristic (ROC) curve was drawn to evaluate the accuracy of the related risk factors. Results:A total of 130 patients were enrolled, with 32 cases in POD group and 98 cases in non-POD group, and the incidence of POD was 24.6%.The results of logistic regression analysis showed that the CPB 2rSO 2 decrease, CPB 2rSO 2 lowest and operation time were independent risk factors for POD ( P<0.05). The area under the ROC curve (95% confidence interval) of CPB 2rSO 2 decrease>11.2% predicting POD was 0.655 (0.533-0.778), sensitivity 68.9%, and specificity 62.9%.The area under the ROC curve (95% confidence interval) of operation time>237.5 min predicting POD was 0.751 (0.652-0.849), sensitivity 62.5%, and specificity 78.6%. Conclusions:CPB 2rSO 2 decrease, CPB 2rSO 2 lowest and operation time are independent risk factors for POD in frail elderly patients undergoing cardiac surgery; both CPB 2rSO 2 decrease and operation time can effectively predict the occurrence of POD in frail elderly patients undergoing cardiac surgery.