title: Does local anesthetic dilution influence the clinical effectiveness of multiple-injection axillary brachial plexus block?: a prospective, double-blind, randomized clinical trial in patients undergoing upper limb surgery.
abstract: OBJECTIVE
  The relationship between the dose, volume, and concentration of local anesthetic and the quality and success of regional anesthesia remains unclear. Our aim was to test whether using 3 different volumes of the same local anesthetic dose influences the success rate of an axillary brachial plexus block with a multiple-injection technique in patients undergoing upper limb surgery.
  
  
  METHODS
  One hundred sixty-five patients were prospectively randomized to 1 of 3 groups. Each group received an axillary block with mepivacaine 400 mg, diluted in 3 different volumes (20, 30, and 40 mL). Outcome measures recorded were the block success rate at 30 mins, sensory and motor onset times, and length of postoperative sensory and motor blockade.
  
  
  RESULTS
  No difference was found in the rate of successful axillary plexus blocks determined when the 30-min follow-up ended among the 3 groups: 94% for 20-mL volume, 94% for 30-mL volume, and 98% for 40-mL volume. The median sensory and motor onset times of anesthesia did not differ. However, postoperative motor blockade and sensory analgesia lasted significantly longer in the patients receiving mepivacaine 400 mg diluted in a volume of 30 mL than in the other groups.
  
  
  CONCLUSIONS
  An axillary brachial plexus block induced with a multiple-injection technique with mepivacaine 400 mg yields a high success rate regardless of the volume of anesthetic injected.
authors.affiliation: Department of Trauma Anesthesia and Pain Management, Centro Traumatologico Ortopedico-ASL RMC, La Sapienza University of Rome, Azienda Ospedaliera Sant'Andrea, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bertini
authors.forename: Stefano
authors.initials: S
authors.lastname: Palmisani
authors.forename: Stefania
authors.initials: S
authors.lastname: Mancini
authors.forename: Ornella
authors.initials: O
authors.lastname: Martini
authors.forename: Rossana
authors.initials: R
authors.lastname: Ioculano
authors.forename: Roberto
authors.initials: R
authors.lastname: Arcioni
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001917:Brachial Plexus / Q000187:drug effects*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage*; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects; D009407:Nerve Block; D011446:Prospective Studies; D012684:Sensory Thresholds / Q000187:drug effects; D013997:Time Factors; D034941:Upper Extremity / Q000601:surgery*
chemical_list: D000779:Anesthetics, Local; D008619:Mepivacaine