Postoperative analgesia was achieved according to the hospital protocol with patient controlled morphine analgesia (1 mg/ml), 1 mg, with a lockout interval of 8 minutes and a maximum 24-hourly limit of 180 mg. respiratory depression defined as the decrease in respiratory rate below 8/min was treated with i.v naloxone 0.2 mg. Nausea and vomiting were treated with i.v granisetron 1 mg and pruritus was treated with i.m promethazine 25 mg.