title: The influence of arm abduction on the anatomic relations of infraclavicular brachial plexus: an ultrasound study.
abstract: BACKGROUND
  Distances from brachial plexus to the coracoid process and the pleura are critical for performing infraclavicular block. We evaluated the influence of arm abduction on the position of the neurovascular bundle relative to the skin, to the coracoid process and to the pleura using ultrasonography.
  
  
  METHODS
  An ultrasound examination of the brachial plexus at the infraclavicular level was performed on 26 patients. Distances from the axillary artery to the skin, to the coracoid process and to the pleura were measured and noted with different degrees of arm abduction (0 degrees , 45 degrees , and 90 degrees ). Vertical infraclavicular brachial plexus block was then performed by means of nerve stimulation in 14 additional patients undergoing hand surgery.
  
  
  RESULTS
  Under ultrasound examination, the distance from the axillary artery to the skin was found to be significantly less with arm abduction (0 degrees : 32 +/- 7 mm, 45 degrees : 29 +/- 7 mm, 90 degrees : 25 +/- 5 mm, P < 0.05). The distance from the skin to the pleura was 47 +/- 5 mm with a medial deviation of 18 +/- 3 degrees and was not influenced by arm position. Brachial plexus was identified by nerve stimulation at a vertical depth of 41 +/- 7 mm from the skin.
  
  
  CONCLUSIONS
  Abduction of the arm reduces the depth of the brachial plexus but does not change the position of the axillary artery relative to the coracoid process or the pleura. Ultrasonography may under-estimate the actual depth of the plexus.
authors.affiliation: Department of Anesthesiology, University of Barcelona, Hospital Clinic, Barcelona, Spain. 32455arp@comb.es
authors.forename: Ana
authors.initials: A
authors.lastname: Ruíz
authors.forename: Xavier
authors.initials: X
authors.lastname: Sala
authors.forename: Xavier
authors.initials: X
authors.lastname: Bargalló
authors.forename: Paola
authors.initials: P
authors.lastname: Hurtado
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Arguis
authors.forename: Ana
authors.initials: A
authors.lastname: Carrera
mesh_terms: D000328:Adult; D001132:Arm / Q000294:innervation*; D001366:Axillary Artery / Q000000981:diagnostic imaging; D001917:Brachial Plexus / Q000000981:diagnostic imaging*; D004558:Electric Stimulation; D005260:Female; D006225:Hand / Q000294:innervation / Q000601:surgery; D006801:Humans; D008297:Male; D009046:Motor Neurons; D009119:Muscle Contraction; D009407:Nerve Block; D010994:Pleura / Q000000981:diagnostic imaging; D012867:Skin / Q000000981:diagnostic imaging; D014463:Ultrasonography; D055815:Young Adult