title: The minimum local anesthetic concentration of ropivacaine for caudal analgesia in children.
abstract: Ropivacaine is a new long-acting amino-amide local anesthetic. The concentrations of ropivacaine used in caudal analgesia range from 0.1% to 0.5%. The purpose of this study was to determine the minimum local analgesic concentration of ropivacaine to provide caudal analgesia in children. In a prospective, randomized, double-blinded clinical study, we studied 26 ASA grade I patients aged 1 to 5 yr who were scheduled for hypospadias operation under general anesthesia with caudal ropivacaine analgesia. General anesthesia was maintained with an end-tidal enflurane concentration of 0.8% in 100% oxygen (0.5 minimum alveolar anesthetic concentration [MAC]). Each child received 1 mL/kg of ropivacaine solution through a caudal catheter. The first child received ropivacaine 0.2%, and subsequent concentrations were determined by the analgesic response of the previous patient to the initial skin incision by use of Dixon's up-and-down sequential allocation. The testing interval was set at 0.025%. The minimum local analgesic concentration of ropivacaine for caudal analgesia under general anesthesia with 0.5 MAC enflurane was 0.11% (95% confidence interval [CI], 0.09%-0.12%), and the 95% effective concentration was 0.13% (95% CI, 0.12%-0.21%). In conclusion, the minimum local analgesic concentration of ropivacaine to provide effective caudal analgesia in children under general anesthesia with 0.5 MAC enflurane was found to be 0.11% (95% CI, 0.09%-0.12%).
  
  
  CONCLUSIONS
  Ropivacaine is a new long-acting amino-amide local anesthetic. The concentrations of ropivacaine used in caudal analgesia ranged from 0.1% to 0.5%. This study determined the minimum local analgesic concentration of ropivacaine to establish effective caudal analgesia under general anesthesia with 0.5 minimum alveolar anesthetic concentration enflurane in children.
authors.affiliation: Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China 100041.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Deng
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Xiao
authors.forename: Geng-Zhi
authors.initials: GZ
authors.lastname: Tang
authors.forename: Mao-Ping
authors.initials: MP
authors.lastname: Luo
authors.forename: Kun-Ling
authors.initials: KL
authors.lastname: Xu
mesh_terms: D000577:Amides; D000698:Analgesia; D000763:Anesthesia, Caudal; D000779:Anesthetics, Local; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D007021:Hypospadias / Q000601:surgery; D007223:Infant; D008297:Male; D010147:Pain Measurement / Q000187:drug effects; D011446:Prospective Studies; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine