Patients often suffer acute pain after operation ，which may affect the recovery. Opioid such as morphine is the most commonly analgesic drugs, but opioid has many obviously adverse reactions ,for example respiratory depression,circulation inhibition,tolerance, addiction, nausea, vomiting, pruritus, etc. S (+) - ketamine has been described to decrease acute pain and opioid consumption,but it needs to confirm for chinese patients undergoing surgery.~Objective:Evaluate the efficacy and safety of S (+) - ketamine on acute perioperative pain for chinese adult patients,and look for the best dosage, mode of administration, timing, and compatibility ,as well explore the effect of S (+) - ketamine on postoperative delirium,anxiety ,depression and cognitive dysfunction.
A multicenter, randomized, open-label, active controlled pragmatic clinical trial that evaluates the safety and efficacy of S (+) -ketamine for postoperative acute pain in adults in perioperative settings.