ED50 and ED95 of pentazocine preemptive analgesia to prevent postoperative hyperalgesia in remifentanil-based anesthesia

Abstract

Objective To determin the 50％ effective dose (ED50) and 95％ effective dose (ED95) of pentazocine preemptive analgesia for preventing the postoperative hyperalgesia after remifentanil-based anesthesia.Methods 180 patients received laparoscopic cholecystectomy were randomly assigned to six pentazocine dose groups (0.10,0.14,0.19,0.26,0.36 and 0.5 mg/kg respectively).The pentazocine was infused by vein at the time of 10 minutes before the beginning of the surgery.Propofol and remifentanil were used for the general anaesthesia by endotracheal tube.Remifentanil was infused at 0.25 μ g/(kg · min).The feeling of pain was evaluated by visual analog scale (VAS) score at the time of 15 minutes after tracheal extubation (VAS＜4,the pentazocine was considered effective).To calculate the ED50 and ED95 to prevent hyperalgesia by using the Probit analysis method.Results The ED50 of pentazocine was 0.240mg/kg (95％CI:0.217 ～ 0.266 mg/kg) and ED95 was 0.473mg/kg(95％CI:0.402 ～ 0.607 mg/kg).Conclusion The ED50 and ED95 of pentazocine preemptive analgesia to prevent the postoperative hyperalgesia in laparoscopie cholecystectomy patients are 0.240 mg/kg and 0.473 mg/kg respectively. Key words: Pentazocine; Preemptive analgesia; Remifentanil; Hyperalgesia; Dose-response relationship