Patient-controlled intravenous morphine and ketamine for postoperative analgesia

Objective to evaluate the effect of ketamine added to patient-controlled intravenous (pci) morphine on postoperative pain, we have compared the analgesic effect of pci morphine and pci morphine with ketamine for postoperative pain in a randomized, double-blind study.Methods Ninety-five asa Ⅰ -Ⅱ patients aged 18-65 yr undergoing elective abdominal hysterectomy under general anesthesia were randomly allocated to one of three groups : (a) group m received pci morphine (bolus 1mg); (b) group mk, received pci morphine (bolus 1mg) + ketamine (bolus 0.04 mg·kg-1 ); (c) group mk2 received pci morphine (bolus 1 mg) + ketamine (bolus 0.07 mg·kg-1 ). The lockout time was 5 min in all three groups. Vas score, bp, hr, rr and spo2 were recorded at 4, 8, 12, 16, 20 and 24 h after operation. Total morphine consumption and side-effects were compared. Results the vas scores were significantly lower in group mk1 and mk2 than that in group m. There were no significant differences in the consumption of morphine, sedation score, and incidence of adverse effects such as nausea vomiting, hallucination, urinary retention and pruritus among the three groups.Conclusion the results suggest that small dose of ketamine can potentiate the analgesic effect of pci morphine without increase in side-effects. A bolus dose of 1mg morphine and 0.04 mg·kg-1 ketamine for pcia is recommended.