Abstract: ObjectiveTo evaluate the effect and the side-effect of continuous intravenous infusion of low dose of ketamine combined with morphine for postoperative analgesia in patients with cervical spinal cord injury, and determine the suitable dosage of ketamine. Methods87 patients with cervical spinal cord injury scheduled for the cervical vertebra operation via posterior routine under intravenous and inhalation combined anesthesia were randomly allocated into three groups, i.e. Group M (morphine 0.02 mg/kg·h), Group MK1 (morphine 0.02 mg/kg·h + ketamine 0.02 mg/kg·h), and Group MK2 (morphine 0.02 mg/kg·h + ketamine 0.04 mg/kg·h), to accept intravenous postoperative analgesia. The pain scores of VAS, sedation scores, the incidence of side-effect including itching, nausea, vomiting, and central excitatory phenomena, and SpO₂ were recorded at 2 h, 4 h, 8 h, 12 h, 24 h and 48 h after operation. ResultsThe pain score of group MK2 at each time point was significantly lower than that of group M or group MK1 (P<0.01), and there was no significant difference between group M and group MK1 (P>0.05). There was not significant difference among the three groups (P>0.05) on sedation scores. No significant difference was found in the incidence of nausea, vomiting, or itching among these groups (P>0.05), although the nausea and vomiting (18.5%) and itching (7.4%) were a little higher in Group M. No case with central excitatory phenomena was found in each group. At each time point, no significant difference was found in SpO₂ among these groups groups (P>0.05), and all the SpO₂ values were not less than 96%. Conclusion0.04 mg/kg·h of ketamine can enhance the efficacy of morphine (0.02 mg/kg·h) and do not increase side-effect events.

Key words: ketamine, morphine, postoperative analgesia, spinal cord injury, cervix