title: [Effects of fentanyl on EC50 of ropivacaine for postoperative epidural analgesia after gynecological surgery].
abstract: OBJECTIVE
  To determine the effect of fentanyl on 50% effective concentration (EC50) of ropivacaine for postoperative epidural analgesia following gynecological surgery.
  
  
  METHODS
  Sixty-five patients (ASA class I to II) scheduled for elective gynecological surgery were randomly divided into two groups to receive 20 ml ropivacaine (group R, n=33) or ropivacaine combined fentanyl (group RF, n=32) for postoperative epidural analgesia. The concentration of ropivacaine was adjusted according to double-blinded up-down sequential allocation. The efficacy was assessed using visual analog scores (VAS) and EC50 calculated using method of Dixon.
  
  
  RESULTS
  The EC50 of ropivacaine was 0.098% in group R and 0.069% in group RF, showing significant difference (P<0.01).
  
  
  CONCLUSIONS
  EC50 of ropivacaine for postoperative epidural analgesia determined by up-down sequential allocation is 0.098%, which can be decreased by the use of fentanyl.
authors.affiliation: Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. mzkgmn@263.net
authors.forename: Jian-she
authors.initials: JS
authors.lastname: Xu
authors.forename: Ji-wu
authors.initials: JW
authors.lastname: Yang
authors.forename: Miao-ning
authors.initials: MN
authors.lastname: Gu
authors.forename: Ye-ming
authors.initials: YM
authors.lastname: Chen
mesh_terms: D000577:Amides / Q000008:administration & dosage*; D015360:Analgesia, Epidural; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage*; D013509:Gynecologic Surgical Procedures; D006801:Humans; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy*; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D000077212:Ropivacaine; D005283:Fentanyl