Patient-controlled epidural analgesia with morphine or morphine plus ketamine for post-operative pain relief

Sixty patients were randomly assigned to two equal groups. Group I received epidural morphine 1 mg after surgery and used a patient-controlled analges ia device programmed to deliver morphine 0.2 mg h(-1), 0.2 mg per bolus. Gr oup II received an epidural loading dose of morphine 1 mg plus ketamine 5 m g and used a patient-controlled analgesia device programmed to deliver morp hine 0.2 mg+ketamine 0.5 mg h(-1), morphine 0.2 mg+ketamine 0.5 mg per bolu s with a lockout time of 10 min. The mean morphine consumption was 8.6 +/- 0.7 mg for group I and 6.2 +/- 0.2 mg for group II. Although group II utili zed significantly less morphine (P < 0.05), pain relief was significantly b etter in group II than in group I (P < 0.05) in the first 3 h. Vomiting occ urred more frequently in group I (26%) than in group II (13%). The frequenc y and severity of pruritus and level of sedation were similar in the two gr oups. These findings suggest that patient-controlled epidural analgesia wit h morphine plus ketamine may provide effective analgesia with a lesser dose of morphine and fewer subsequent side effects, compared with patient-contr olled epidural analgesia with morphine alone after lower abdominal surgery.