title: Effect of local anesthetic concentration, dose and volume on the duration of single-injection ultrasound-guided axillary brachial plexus block with mepivacaine: a randomized controlled trial.
abstract: BACKGROUND
  In what way volume, concentration and dose affect block duration is controversial. The purpose of the present study is to investigate the effect of dose, volume and concentration of mepivacaine on the duration of sensory and motor blockade in ultrasound-guided single shot axillary brachial plexus blockade.
  
  
  METHODS
  In this parallel group randomized trial conducted in the Sint Maartenskliniek Nijmegen, 45 adult patients undergoing minor orthopaedic forearm, wrist or hand surgery were randomized to 3 groups. Group A: 20 mL mepivacaine 1.5 %, Group B: 30 mL mepivacaine 1 % and Group C: 30 mL mepivacaine 1.5 %. Randomization was computer-generated, with allocation concealment by opaque sequentially numbered sealed envelopes. Patients and observers were blinded to group allocation.
  
  
  METHODS
  duration of sensory block.
  
  
  RESULTS
  Forty-five patients were randomized, four patients were excluded and replaced, and 15 patients in each group were included in the analysis. Mean (95 % CI) sensory and motor block duration was 256 (230-282) and 254 (226-282) minutes in Group A, 226 (209-243) and 220 (200-240) minutes in Group B and 270 (249-291) and 264 (244-284) minutes in Group C. Duration of sensory and motor block duration differed significantly between groups (p = 0.012 and p = 0.016 respectively). Post-hoc analysis showed a significantly reduced sensory and motor block duration in Group B when compared to Group C of 44 min. No local anesthetic systemic toxicity was reported.
  
  
  CONCLUSIONS
  When using mepivacaine for axillary brachial plexus block, a higher dose and concentration was associated with a longer duration of sensory and motor blockade, but not a higher volume.
  
  
  BACKGROUND
  The Netherlands National Trial Register NTR3648 . Registered October 3, 2012.
authors.affiliation: Department of Anesthesiology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Maaike G E
authors.initials: MG
authors.lastname: Fenten
authors.affiliation: Department of Anesthesiology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Karin P W
authors.initials: KP
authors.lastname: Schoenmakers
authors.affiliation: Research Department, Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: Petra J C
authors.initials: PJ
authors.lastname: Heesterbeek
authors.affiliation: Department of Anesthesiology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: Scheffer
authors.affiliation: Department of Anesthesiology, Sint Maartenskliniek, Postbox 9011, 6500, GM, Nijmegen, The Netherlands. r.stienstra@maartenskliniek.nl.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stienstra
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology*; D001917:Brachial Plexus / Q000000981:diagnostic imaging / Q000187:drug effects; D065527:Brachial Plexus Block / Q000379:methods* / Q000706:statistics & numerical data; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D013997:Time Factors; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local; D008619:Mepivacaine