Analgesia after hip replacement surgery: comparison of nalbuphine with morphine

Two groups of 40 patients undergoing hip replacement received either nalbuphine 0.3 mg kg-1 or morphine 0.15 mg kg-1 i.m. on up to three occasions: 1 h before operation, as soon as requested after operation, and 3 h subsequently if required. Pain intensity was assessed by the patient as severe, moderate or none, and pain relief by a "blind" nurse observer as slight, moderate or complete. Assessments of pain and sedation were carried out at 30-min intervals for 2 h and at 1-h intervals thereafter for up to 6 h. Six patients who received nalbuphine and eight who received morphine before operation required no postoperative analgesia. Ten patients in the nalbuphine group and two in the morphine group failed to obtain adequate pain relief (P less than 0.05) and were given i.v. morphine.