title: A prospective, randomized comparison between single- and double-injection, ultrasound-guided supraclavicular brachial plexus block.
abstract: OBJECTIVE
  This prospective, randomized, observer-blinded study compared single- and double-injection, ultrasound-guided supraclavicular brachial plexus block for upper extremity surgery.
  
  
  METHODS
  Ninety-two patients were randomly allocated to receive a single-injection (n = 46) or double-injection (n = 46), ultrasound-guided supraclavicular block. Performance time (defined as the sum of imaging and needling times) and the number of needle passes were recorded during the performance of the block. Subsequently, a blinded observer recorded the onset time, block-related pain scores, success rate (surgical anesthesia), and the incidence of complications. The total anesthesia-related time was defined as the sum of the performance and onset times. The main outcome variable was the onset time.
  
  
  RESULTS
  The onset time was shorter with the 2-injection technique (17.5 mins [SD, 8.4 mins] vs 21.7 mins [SD, 7.2 mins]; P = 0.021); however, performance time was also longer (7.2 mins [SD, 2.7 mins] vs 6.0 mins [SD, 2.4 mins]; P = 0.037). Thus, no differences were observed in terms of total anesthesia-related time (23.4-24.3 mins). Success rates (95.7%), block-related pain scores, and complication rates were also similar between the 2 groups. As expected, the 2-injection technique required a greater number of needle passes (3.5 [SD, 1.2] vs 1.9 [SD, 1.1]; P < 0.001). In return, it provided a faster onset for sensory and motor block of the musculocutaneous nerve and a faster sensory block of the radial nerve. However, at 30 mins, no differences were observed.
  
  
  CONCLUSIONS
  The double-injection, ultrasound-guided supraclavicular block provides no significant advantages compared with its single-injection counterpart.
authors.affiliation: Department of Anesthesia, McGill University, Montreal General Hospital, Montreal, Quebec, Canada. de_tran@hotmail.com
authors.forename: De Q H
authors.initials: DQ
authors.lastname: Tran
authors.forename: Loreto
authors.initials: L
authors.lastname: Muñoz
authors.forename: Cedrick
authors.initials: C
authors.lastname: Zaouter
authors.forename: Gianluca
authors.initials: G
authors.lastname: Russo
authors.forename: Roderick J
authors.initials: RJ
authors.lastname: Finlayson
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects; D001917:Brachial Plexus / Q000000981:diagnostic imaging* / Q000187:drug effects*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects; D009407:Nerve Block / Q000009:adverse effects; D010149:Postoperative Pain / Q000517:prevention & control; D011446:Prospective Studies; D012684:Sensory Thresholds / Q000187:drug effects; D013997:Time Factors; D018084:Ultrasonography, Interventional; D034941:Upper Extremity / Q000601:surgery; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local