METHODS	The patients in the IV group ( n = 15 ) received modified neurolept anesthesia with droperidol 0.2 mgxkg ( -1 ) and pentazocine 0.15-0 .3 mgxkg ( -1 ) ( maximum dose of 1.0 mgxkg ( -1 ) ) and 60 % nitrous oxide in oxygen , followed by postoperative intravenous infusion of 20 microgxml ( -1 ) buprenorphine , provided with a patient-controlled analgesia pump programmed to deliver a bolus of 0.5 ml with a lockout interval of 15 min and a background infusion of 0.5 mlxh ( -1 ) .\