title: Relative analgesic potencies of levobupivacaine and ropivacaine for caudal anesthesia in children.
abstract: BACKGROUND
  Comparing relative potency of new local anesthetics, such as levobupivacaine and ropivacaine, by the minimum local analgesic concentration model has not been described for caudal anesthesia. Therefore, we performed a prospective, randomized, double-blind study to determine the minimum local analgesic concentrations of a caudal single shot of ropivacaine and levobupivacaine in children and to describe the upper dose-response curve.
  
  
  METHODS
  We performed a two-stage prospective, randomized, double-blind study comparing the dose-response curves of caudal ropivacaine and levobupivacaine in children. In phase 1, 80 boys were randomized to receive either ropivacaine or levobupivacaine. In the second phase a further 32 patients were randomly allocated to receive caudal anesthesia with doses designed to delineate the upper dose-response range (the 50% effective dose [ED(50)]-ED(95) range).
  
  
  RESULTS
  There were no significant differences in ED(50) values for caudal ropivacaine and levobupivacaine. The ED(50) for levobupivacaine estimated from the Dixon Massey method was 0.069% (95% CI 0.056%-0.082%) and for ropivacaine was 0.075% (95% CI 0.058%-0.092%). Estimated by isotonic regression the ED(50) and ED(95) respectively of levobupivacaine were 0.068 (0.04-0.09) and 0.20% (95% CI 0.16%-0.24%). For ropivacaine ED 50 and ED95 were 0.066 (0.033-0.098) and 0.225% (95% CI 0.21%-0.24%).
  
  
  CONCLUSIONS
  In children receiving one minimum alveolar anesthetic concentration of sevoflurane, there were no significant differences in the ED(50) for caudal levobupivacaine and ropivacaine. The potency ratio at ED(50) was 0.92 and 0.89 at ED(95), indicating that caudal levobupivacaine and ropivacaine have a similar potency.
authors.affiliation: Department of Perioperative Medicine and Intensive, A.O. San Gerardo, Monza, Italy.
authors.forename: Pablo
authors.initials: P
authors.lastname: Ingelmo
authors.forename: Geoff
authors.initials: G
authors.lastname: Frawley
authors.forename: Marinella
authors.initials: M
authors.lastname: Astuto
authors.forename: Chris
authors.initials: C
authors.lastname: Duffy
authors.forename: Susan
authors.initials: S
authors.lastname: Donath
authors.forename: Nicola
authors.initials: N
authors.lastname: Disma
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rosano
authors.forename: Roberto
authors.initials: R
authors.lastname: Fumagalli
authors.forename: Antonio
authors.initials: A
authors.lastname: Gullo
mesh_terms: D000577:Amides / Q000008:administration & dosage; D000763:Anesthesia, Caudal; D000779:Anesthetics, Local / Q000008:administration & dosage; D002045:Bupivacaine / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006552:Hernia, Inguinal / Q000601:surgery; D006801:Humans; D007223:Infant; D008297:Male; D009068:Movement / Q000502:physiology; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000453:epidemiology; D011229:Preanesthetic Medication; D011446:Prospective Studies; D012044:Regression Analysis; D000077212:Ropivacaine; D013737:Testis / Q000002:abnormalities / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine