Investigation of the effect of ketamine injected preoperatively on preventing remifentanil-induced hyperalgesia

Objective To investigate the effect of ketamine injected preoperatively on preventing remifentanil-induced hyperalgesia.Methods A total of 60 patients scheduled for receiving ketamine procedure under general anesthesia were randomly divided into three groups(n=20).2 ml normal saline,0.25 mg/kg and 0.5 mg/kg tramadol was intravenously injected before anesthesia in Groups Ⅰ,Ⅱand Ⅲ,respectively.Visual analog scale(VAS) pain save and Ramsay Sedation score were measured at postoperative 1,2,4,8,12 and 24 h,respectively.Adverse effects were also recorded.Results The VAS save was significantly lower within postoperative 8 hours in Groups Ⅱ and Ⅲ than that in GroupⅠ,while no significant difference was found among Groups Ⅱ and Ⅲ at each time point.Incidence of postoperative dysphoria,dizziness,nausea was higher in Groups Ⅱ and Ⅲ than that in Group Ⅰ,but there was no significant difference among the three groups.Conclusion Preoperative injection of 0.25-0.5 mg/kg ketamine prevents the development of remifentamil-induced hyperalgesia and reduces incidence of side effects.