title: No differences between 20, 30, or 40 mL ropivacaine 0.5% in continuous lateral popliteal sciatic-nerve block.
abstract: OBJECTIVE
  The aim of this study was to compare the anesthetic and analgesic characteristics of the administration of an initial bolus of 20, 30, or 40 mL of ropivacaine 0.5% through a lateral popliteal sciatic catheter.
  
  
  METHODS
  Sixty patients scheduled for foot surgery under continuous sciatic lateral popliteal nerve block were included in this double-blinded study. Patients were randomly assigned to 1 of 3 groups: 20 mL, 30 mL, or 40 mL of ropivacaine 0.5%. Time to obtain a complete sensory block and duration of analgesia were recorded. Failure of the continuous block and complications such as technical or neurologic problems were noted.
  
  
  RESULTS
  Data are presented as mean +/- SD, median and ranges, or percent of patients and were compared by application of analysis of variance or Kruskal-Wallis when required. Time to complete sensory block (31 [10-70] v 25 [5-50] v 25 [5-40] min), percentage of failure (5% v 5% v 0%), and duration of action (995 [278-1,800] v 967 [420-2,175] v 915 [190-1,900] min) were not statistically different between 20 mL, 30 mL, and 40 mL ropivacaine 0.5% groups, respectively. No complications were noted.
  
  
  CONCLUSIONS
  This dose-response study shows that 20 mL of ropivacaine 0.5% injected through an indwelling lateral popliteal catheter is the optimal dose for foot surgery. Higher doses of 30 mL or 40 mL did not provide any further advantage.
authors.affiliation: Department of Anaesthesiology, University Hospital of Geneva, Geneva, Switzerland. Roxane.Fournier@hcuge.ch
authors.forename: Roxane
authors.initials: R
authors.lastname: Fournier
authors.forename: Anne
authors.initials: A
authors.lastname: Weber
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Gamulin
mesh_terms: D000328:Adult; D000368:Aged; D000577:Amides / Q000008:administration & dosage*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D000077212:Ropivacaine; D012584:Sciatic Nerve
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine