title: Ultrasound guidance improves the success rate of a perivascular axillary plexus block.
abstract: BACKGROUND
  Traditional approaches to performing brachial plexus blocks via the axillary approach have varying success rates. The main objective of this study was to evaluate if a specific technique of ultrasound guidance could improve the success of axillary blocks in comparison to a two injection transarterial technique.
  
  
  METHODS
  Fifty-six ASA physical status I-III patients presenting for elective hand surgery were prospectively randomized to receive an axillary block performed by either a transarterial technique (Group TA) or an ultrasound-guided perivascular approach (Group US). Both groups received a total of 30 ml of 1.5% lidocaine (225 mg) with 5 microg/ml epinephrine. Patients were then evaluated for block onset in specific nerve distributions and whether or not the block acted as a surgical anesthetic.
  
  
  RESULTS
  Group TA sustained more failures defined as conversion to general anesthesia or the inability to localize the artery [Group TA eight patients (29%) vs. Group US in which 0 patients required conversion to general anesthesia (0%) P < 0.01]. Group US demonstrated a reduction in performance times vs. Group TA (7.9 +/- 3.9 min vs. 11.1 +/- 5.7 min, P < 0.05). By 30 min post-injection, there were no significant differences between groups TA and US in terms of the proportion of patients demonstrating a complete motor or sensory loss.
  
  
  CONCLUSIONS
  Ultrasonographic guidance improves the overall success rate of axillary blocks in comparison to a transarterial technique.
authors.affiliation: Department of Anesthesiology, Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA. brian.sites@hitchcock.org
authors.forename: B D
authors.initials: BD
authors.lastname: Sites
authors.forename: M L
authors.initials: ML
authors.lastname: Beach
authors.forename: B C
authors.initials: BC
authors.lastname: Spence
authors.forename: C W
authors.initials: CW
authors.lastname: Wiley
authors.forename: J
authors.initials: J
authors.lastname: Shiffrin
authors.forename: G S
authors.initials: GS
authors.lastname: Hartman
authors.forename: J D
authors.initials: JD
authors.lastname: Gallagher
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local; D001917:Brachial Plexus / Q000000981:diagnostic imaging*; D004837:Epinephrine; D005260:Female; D006225:Hand / Q000601:surgery; D006801:Humans; D007269:Injections, Intra-Arterial; D008012:Lidocaine; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009407:Nerve Block; D019637:Orthopedic Procedures; D011446:Prospective Studies; D016037:Single-Blind Method; D017211:Treatment Failure; D014463:Ultrasonography; D014662:Vasoconstrictor Agents
chemical_list: D000779:Anesthetics, Local; D014662:Vasoconstrictor Agents; D008012:Lidocaine; D004837:Epinephrine