title: Combined versus sequential injection of mepivacaine and ropivacaine for supraclavicular nerve blocks.
abstract: BACKGROUND
  An ideal local anesthetic with rapid onset and prolonged duration has yet to be developed. Clinicians use mixtures of local anesthetics in an attempt to combine their advantages. We tested the hypothesis that sequential supraclavicular injection of 1.5% mepivacaine followed 90 secs later by 0.5% ropivacaine speeds onset of sensory block and prolongs duration of analgesia compared with simultaneous injection of the same 2 local anesthetics.
  
  
  METHODS
  We enrolled 103 patients undergoing surgery suitable for supraclavicular anesthesia. The primary outcome was time to 4-nerve sensory block onset in each of the 4 major nerve distributions: median, ulnar, radial, and musculocutaneous. Secondary outcomes included time to onset of first sensory block, time to complete motor block, duration of analgesia, pain scores at rest and with movement, and total opioid consumption. Outcomes were compared using the Kaplan-Meier analysis with the log-rank test or the analysis of variance, as appropriate.
  
  
  RESULTS
  Times to 4-nerve sensory block onset were not different between sequential and combined anesthetic administration. The time to complete motor block onset was faster in the combined group as compared with the sequential. There were not significant differences between the 2 randomized groups in other secondary outcomes, such as the time to onset of first sensory block, the duration of analgesia, the pain scores at rest or with movement, or the total opioid consumption.
  
  
  CONCLUSIONS
  Sequential injection of 1.5% mepivacaine followed 90 secs later by 0.5% ropivacaine provides no advantage compared with simultaneous injection of the same doses.
authors.affiliation: Department of Anesthesiology, Drexel University College of Medicine, Philadelphia, PA, USA.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Roberman
authors.forename: Harendra
authors.initials: H
authors.lastname: Arora
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Michael
authors.initials: M
authors.lastname: Ritchey
authors.forename: Jing
authors.initials: J
authors.lastname: You
authors.forename: Priya
authors.initials: P
authors.lastname: Kumar
mesh_terms: D000328:Adult; D000577:Amides / Q000008:administration & dosage*; D000779:Anesthetics, Local; D002968:Clavicle / Q000294:innervation; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage*; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010149:Postoperative Pain / Q000473:pathology / Q000517:prevention & control*; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D008619:Mepivacaine