title: Determination of the minimum effective volume of 0.5% bupivacaine for ultrasound-guided axillary brachial plexus block.
abstract: OBJECTIVE
  The use of ultrasound for needle correct placement and local anesthetic spread monitoring helped to reduce the volume of local anesthetic required for peripheral nerve blocks. There are few studies of the minimum effective volume of local anesthetic for axillary brachial plexus block. The aim of this study was to determine the minimum effective volume (VE90) of 0.5% bupivacaine with epinephrine (1:200,000) for ultrasound guided ABPB.
  
  
  METHODS
  Massey and Dixon's up-and-down method was used to calculate the minimum effective volume. The initial dose was 5 mL per nerve (radial, median, ulnar, and musculocutaneous). In case of blockade failure, the volume was increased to 0.5 mL per nerve. A successful blockade resulted in decreased volume of 0.5 mL per nerve to the next patient. Successful blockade was defined as a motor block ≤2, according to the modified Bromage scale; lack of thermal sensitivity; and response to pinprick. The achievement of five cases of failure followed by success cases was defined as criterion to complete the study.
  
  
  RESULTS
  19 patients were included in the study. The minimum effective volume (VE90) of 0.5% bupivacaine with 1:200,000 epinephrine was 1.56 mL (95% CI, 0.99-3.5) per nerve.
  
  
  CONCLUSIONS
  This study is in agreement with some other studies, which show that it is possible to achieve surgical anesthesia with low volumes of local anesthetic for ultrasound-guided peripheral nerve blocks.
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil. Electronic address: leohcferraro@yahoo.com.br.
authors.forename: Leonardo Henrique Cunha
authors.initials: LH
authors.lastname: Ferraro
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Takeda
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: dos Reis Falcão
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: André Hosoi
authors.initials: AH
authors.lastname: Rezende
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Eduardo Jun
authors.initials: EJ
authors.lastname: Sadatsune
authors.affiliation: Disciplina de Anestesiologia, Dor e Terapia Intensiva, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Maria Angela
authors.initials: MA
authors.lastname: Tardelli
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage*; D065527:Brachial Plexus Block / Q000379:methods*; D002045:Bupivacaine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine
keywords: Brachial plexus; Bupivacaine; Minimum volume; Regional anesthesia; Ultrasound