Abstract: To the Editor:In a randomized controlled preliminary trial comparing effects of propofol,dexmedetomidine,and midazolam on postoperative cognitive dysfunction (POCD) in elderly patients undergoing hip or knee arthroplasty with combined spinal-epidural anesthesia,Li et al[1] showed that intraoperative sedation with propofol compared to dexmedetomidine can significantly decrease risk of POCD.