The purpose of this study was to evaluate the effect of low dose i.v. ketamine in combination with epidural morphine on postoperative pain after gastrectomy.

40 patients scheduled for elective gastrectomy were investigated in a randomized study. All patients received epidural morphine (0.05 mg/kg) and bupivacaine (0.25%) as a bolus dose of 10 ml 40 min prior to skin incision. In addition, patient-controlled epidural analgesia (PCEA) with epidural bupivacaine (0.125%) and morphine (0.1 mg/ml) (bolus dose 1 ml, continuous infusion 1 ml/h, lock out interval 15 min) was offered from the time after 10 ml bolus dose. In the ketamine group, ketamine 0.5 mg/kg was administered 10 min prior to skin incision and then maintained continuously until skin closure at a dosage of 10µgram/kg/min. In the second group anesthesia was induced with thiopental sodium 4 mg/kg, midazolam 0.5 mg/kg, vecuronium 0.1 mg/kg and maintained with 66% N₂O-O₂, 1-3 vol% enflurane. The intensities of spontaneous pain and of coughing associated pain were measured using a visual analogue scale. Cumulative morphine consumption was measured at 2, 6, 12, 24, 48 h after surgery. Side effects were evaluated at 48 h after surgery.

VAS and cumulative morphine consumption at 2, 6, 12, 24, 48 h postoperatively showed no statistical differences between the two groups, and no statistical differences in side effects were observed at 48h after surgery.

We were unable to demonstrate any additional analgesic effect of low dose i.v. ketamine in combination with epidural morphine and bupivacaine.