title: A cadaveric study to determine the minimum volume of methylene blue to completely color the nerves of brachial plexus in cats. An update in forelimb and shoulder surgeries.
abstract: OBJECTIVE
  To determine the minimum volume of methylene blue (MB) to completely color the brachial plexus (BP) nerves, simulating an effective anesthetic block in cats.
  
  
  METHODS
  Fifteen adult male cat cadavers were injected through subscapular approach with volumes of 2, 3, 4, 5 and 6 ml in both forelimbs, for a total of 30 brachial plexus blocks (BPB). After infusions, the specimens were carefully dissected preserving each nervous branch. The measurement of the effective area was indicated by the impregnation of MB. Nerves were divided into four segments from the origin at the spinal level until the insertion into the thoracic limb muscles. The blocks were considered effective only when all the nerves were strongly or totally colored.
  
  
  RESULTS
  Volumes of 2, 3 and 4 ml were considered insufficient suggesting a failed block, however, volumes of 5 and 6 ml were associated with a successful block.
  
  
  CONCLUSIONS
  The injection of methylene blue, in a volume of 6 ml, completely colored the brachial plexus. At volumes of 5 and 6 ml the brachial plexus blocks were considered a successful regional block, however, volumes of 2, 3 and 4 ml were considered a failed regional block.
authors.affiliation: Department of Veterinary Surgery and Anestesiology, School of Veterinary Medicine, Valença Higher Education Center, Valença, RJ, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Mencalha
authors.affiliation: School of Veterinary Medicine, CESVA, Valença, RJ, Brazil.
authors.forename: Neide
authors.initials: N
authors.lastname: Fernandes
authors.affiliation: School of Biology, Animal Anatomy Area, Federal Rural University of Rio de Janeiro, Seropedica, RJ, Brazil.
authors.forename: Carlos Augusto dos Santos
authors.initials: CA
authors.lastname: Sousa
authors.affiliation: Department of Animal Biology, Anatomy Area, School of Veterinary Medicine, UFRRJ, Seropedica, RJ, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Abidu-Figueiredo
mesh_terms: D000772:Anesthesia, Local / Q000379:methods / Q000662:veterinary*; D000818:Animals; D001917:Brachial Plexus / Q000033:anatomy & histology / Q000187:drug effects*; D002102:Cadaver; D002415:Cats; D004396:Coloring Agents / Q000008:administration & dosage*; D004210:Dissection; D005552:Forelimb / Q000294:innervation / Q000601:surgery*; D008297:Male; D008488:Medical Illustration; D008751:Methylene Blue / Q000008:administration & dosage*; D009407:Nerve Block / Q000379:methods; D056347:Neuroanatomical Tract-Tracing Techniques / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D012782:Shoulder / Q000294:innervation / Q000601:surgery*
chemical_list: D004396:Coloring Agents; D008751:Methylene Blue