title: The effect of remifentanil on the minimum alveolar concentration of isoflurane in children.
abstract: OBJECTIVE
  To evaluate the effect of remifentanil on the isoflurane end-tidal concentration required to eliminate movement reaction upon surgical incision in children.
  
  
  METHODS
  Prospective, double blinded, serial study.
  
  
  METHODS
  Operating room of a university-affiliated hospital.
  
  
  METHODS
  Patients of ASA status 1 or 2, aged 4 to 7 years, scheduled for either inguinal hernia repair or orchidopexy surgery with general anesthesia.
  
  
  METHODS
  After endotracheal intubation, 108 children serially received 1 of 6 dose (nil, 0.05, 0.10, 0.15, 0.20, or 0.25 μg kg(-1) min(-1)) of remifentanil. End-tidal isoflurane concentration was adjusted according to a Dixon's up-and-down approach. Twenty-five minutes after starting the remifentanil infusion, the surgical incision was performed. The response of patients was classified as either "response" or "no response." Response was defined as a purposeful response in response to skin incision.
  
  
  RESULTS
  The MAC of isoflurane were 1.50 ± 0.16%, 1.33 ± 0.27%, 0.93 ± 0.13%, 0.73 ± 0.27%, 0.63 ± 0.19%, and 0.60 ± 0.15% for remifentanil infusion rates of nil, 0.05, 0.10, 0.15, 0.20, and 0.25 μg kg(-1) min(-1), respectively.
  
  
  CONCLUSIONS
  The MAC of isoflurane decreased with increasing infusion rate of remifentanil, showing an initial step reduction followed by a ceiling effect.
authors.affiliation: Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China; Department of Anesthesiology, Sichuan Provincial Hospital for Women and Children, Chengdu, Sichuan, China.
authors.forename: Ben-zhen
authors.initials: BZ
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Qin-jun
authors.initials: QJ
authors.lastname: Chu
authors.affiliation: Sichuan Provincial Hospital for Women and Children, Chengdu, Sichuan, China.
authors.forename: Jing-rui
authors.initials: JR
authors.lastname: Yu
authors.affiliation: Department of Anesthesiology, Fujian Provincial Hospital, Fuzhou, Fujian, China.
authors.forename: Yu-sheng
authors.initials: YS
authors.lastname: Yao
authors.affiliation: Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China. Electronic address: chenzhen19830320@163.com.
authors.forename: Ling
authors.initials: L
authors.lastname: Tan
mesh_terms: D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics*; D018686:Anesthetics, Intravenous; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006552:Hernia, Inguinal / Q000601:surgery; D059685:Herniorrhaphy; D006801:Humans; D007530:Isoflurane / Q000493:pharmacokinetics*; D008297:Male; D010880:Piperidines; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000378:metabolism*; D000077208:Remifentanil
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D010880:Piperidines; D007530:Isoflurane; D000077208:Remifentanil
keywords: Children; Isoflurane; Minimum alveolar concentration; Remifentanil