title: The ED50 and ED95 of ketamine for prevention of postoperative hyperalgesia after remifentanil-based anaesthesia in patients undergoing laparoscopic cholecystectomy.
abstract: OBJECTIVE
  Various research programmes have shown that intraoperative infusion of remifentanil has been associated with postoperative hyperalgesia. Previous studies have demonstrated that low-dose ketamine can inhibit central sensitisation and prevent opioid-induced hyperalgesia (OIH). However, the optimal ketamine dose to prevent OIH has not been determined. In the present study we aimed to determine the ED50 and ED95 of ketamine for prevention of postoperative hyperalgesia after remifentanil-based anaesthesia in patients undergoing laparoscopic cholecystectomy.
  
  
  METHODS
  Fifty-four patients undergoing laparoscopic cholecystectomy were randomised into two groups: group C and group K. Group K was given ketamine before skin incision. An equal volume of normal saline was given to the patients in group C. Pain was assessed using visual analog scale (VAS) at 10 min after tracheal extubation. The ED50 and ED95 were determined by modified up-and-down method and the incidences of adverse effects were recorded.
  
  
  RESULTS
  The incidences of adverse effects were similar in the two groups and the VAS score was significantly lower in group K than in group C. The ED50 and ED95 of ketamine for prevention of postoperative hyperalgesia were 0.24 mg/kg (95%CI, 0.20~0.30 mg/kg) and 0.33 mg/kg (95%CI, 0.28~0.62 mg/kg) respectively.
  
  
  CONCLUSIONS
  The ED50 and ED95 of ketamine for prevention of postoperative hyperalgesia after remifentanil-based anaesthesia in patients undergoing laparoscopic cholecystectomy were 0.24 mg/kg and 0.33 mg/kg respectively.
authors.affiliation: Department of Anesthesiology, The Affiliated People's Hospital of Jiangsu University, Jiangsu, P.R. China. hanglihua@yahoo.cn
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Hang
authors.forename: Dong-Hua
authors.initials: DH
authors.lastname: Shao
authors.forename: Yue-Ping
authors.initials: YP
authors.lastname: Gu
mesh_terms: D000700:Analgesics / Q000008:administration & dosage*; D018686:Anesthetics, Intravenous / Q000009:adverse effects*; D017081:Cholecystectomy, Laparoscopic; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000517:prevention & control*; D007649:Ketamine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000139:chemically induced / Q000517:prevention & control*; D010880:Piperidines / Q000009:adverse effects*; D000077208:Remifentanil
chemical_list: D000700:Analgesics; D018686:Anesthetics, Intravenous; D010880:Piperidines; D007649:Ketamine; D000077208:Remifentanil