Perioperative antinociceptive effects of tramadol. A prospective, randomized, double-blind comparison with morphine

To compare the efficacy of tramadol and morphine for intra- and postoperative analgesia in patients undergoing laparoscopic cholecystectomy.

In a prospective, randomized, double-blind study 100 patients were allocated randomly into two groups. Ten minutes before induction of anaesthesia, patients in group 1 received 100 mg tramadol and those in group 2 received 10 mg morphine i.v. Anaesthesia was induced with 5 mg.kg-1 thiopental and was maintained with O2, N2O plus isoflurane with additional doses of tramadol or morphine as decided by the attending anaesthetist. Postoperatively, patients in group 1 and group 2 received tramadol and morphine, respectively, from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr.

Intraoperative consumption of tramadol and morphine were 137 +/- 37 and 12.2 +/- 3 mg, respectively. Compared with morphine, patients receiving tramadol had higher blood pressures and required greater mean ETisQ to control haemodynamic variables (P < 0.05). Postoperatively, there were no differences in observer pain score or visual analogue pain score during the first 24 hr between groups except at 30, 45, and 90 min where patients in the tramadol group reported higher pain scores (P < 0.05). The cumulative, 24 hr PCA consumption was 111 +/- 93 and 7.5 +/- 6.6 mg of tramadol and morphine, respectively.

There was no difference between the use of tramadol and morphine to treat pain after laparoscopic cholecystectomy from 90 min after the end of surgery. Morphine was more effective than tramadol as an intraoperative analgesic.