Comparison of Preventive Effects of Dexmedetomidine and Ketamine on Remifentanil-induced Postanesthetic Hyperalgesia

OBJECTIVE To compare the preventive effects of dexmedetomidine and ketamine on remifentanil-induced postanesthetic hyperalgesia. METHODS Ninety patients undergoing elective total abdominal hysterectomy were randomly divided into three groups: control group, dexmedetomidine group and ketamine group. In all groups, anesthesia was maintained with remifentanil 0.4 mg·kg^-1·min^-1 in combination with sevoflurane. The same volume of saline, dexmedetomidine 1 mg·kg^-1 or ketamine 0.8 mg·kg^-1 were injected intravenously in the three groups respectively 30 min before skin closure. VAS scores were recorded within 2 h and at 4, 8, 12, 24 and 48 h after awaking. The amount of pethidine consumed and postoperative side effects were recorded. The extubation and awaking time were also recorded. RESULTS The amount of pethidine consumed was smaller wihin 2 h and 48 h after awaking and VAS scores were significantly lower within 2 h after awaking in group dexmedetomidine and ketamine than the control group. There was no significant difference between dexmedetomidine group and ketamine group. Three patients experienced diplopia and one had hallucination. CONCLUSION Both dexmedetomidine and ketamine have significant preventive effects on hyperalgesia induced by remifentanil but there are no significant differences between them.