Accuracy of regional cerebral oxygen saturation in predicting postoperative cognitive dysfunction after total hip arthroplasty: regional cerebral oxygen saturation predicts POCD.

To estimate the accuracy of regional cerebral oxygen saturation (rSO(2)) in predicting postoperative cognitive dysfunction (POCD) for patients undergoing total hip arthroplasty, 46 patients aged more than 50years old were enrolled. We measured the patients' cognitive function by using a battery of six neuropsychological tests before surgery and then 7days after surgery again. rSO(2) was continuously monitored by near-infrared spectroscopy during surgery. POCD was present in 9 (19.6%) patients 1week after surgery. Logistic regression analysis showed that increasing age [OR=1.224, P=0.035] and maximum percentage drop in rSO(2) (rSO(2%max)) [OR=1.618, P=0.011] were significant risk factors for POCD. The area under the receiver operating characteristic curve of rSO(2%max) was 0.833 [95% confidence interval (CI) 0.615-1.051] at cutoff value of 11%. The specificity and sensitivity of rSO(2%max) >11% in predicting POCD were 77.8% and 86.5%, respectively. rSO(2%max) more than 11% was a potential predictor for POCD.