Investigators investigates the effect of perioperative dexmedetomidine 0.5 ug/kg/hr followed
by a postoperative continuous infusion fentanyl-based PCA(Patient-Controlled Analgesia) drug
mixed with dexmedetomidine 0.2ug/kg/hr for two days on reducing postoperative delirium and
postoperative rescue analgesics in elderly patients who undergo hip surgery. The other half
of patients received fentanyl-based PCA only.