Influence of arm position on ultrasound visibility of the axillary brachial plexus

Vedran Frkovic, Catherine Ward, Benedikt Preckel, Phillip Lirk, Markus W. Hollmann, Markus F. Stevens, Jessica T. Wegener

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7 Citations (Scopus)

Abstract

BACKGROUND Contemporary axillary brachial plexus block is performed by separate injections targeting radial, median, ulnar and musculocutaneous nerve. These nerves are arranged around the axillary artery, making ultrasound visualisation sometimes challenging. In particular, the radial nerve can be difficult to localise deep to the artery. OBJECTIVES The primary aim of this study was to investigate which arm position optimises the visibility of the radial nerve. Secondary aims were the visibility and position of the other nerves during varying arm positions. DESIGN A prospective observational study. SETTING University teaching hospital, November 2012. PARTICIPANTS Twenty volunteers, recruited by an advertisement on the Department's bulletin board. Inclusion criterion age more than 18 years. Exclusion criteria: refusal of ultrasound examination, restricted shoulder movement, local infection, BMI greater than 30 kgm(-2). INTERVENTION One anaesthesiologist performed bilateral ultrasound examinations of the axillary brachial plexus on 20 volunteers. Each arm was placed in different positions [shoulder (S) 90 degrees or 180 degrees abduction, elbow (E) 0 degrees or 90 degrees extension] and scans were performed proximally in the axilla, and additionally 5cm distally to this point [proximal (P) vs. distal (D)], resulting in eight different scans stored for off-line analysis performed by two blinded anaesthesiologists. MAIN OUTCOME MEASURES For radial, median, ulnar and musculocutaneous nerve, visibility was assessed on a sixpoint visibility scale. Distances and angles of the nerves relative to the axillary artery and distances relative to the skin were measured. RESULTS No significant differences between arm positions were found in the visibility score of radial (P = 0.359) and musculocutaneous nerves (P = 0.073). Visibility of the median nerve was improved in positions S90 degrees/E0 degrees/D and S180 degrees/E0 degrees/P (P = 0.02). The ulnar nerve was more visible in position S180 degrees/E 0 degrees/P and D (P = 0.007). The greatest distance between artery and radial nerve was 7.4 +/- 4.7mm at an angle of 120 +/- 14 degrees in position S180 degrees/E 0 degrees/D. CONCLUSION The visibility of the radial nerve was not improved by varying positions of the arm. S180 degrees/E0 degrees provided the best overall visibility and accessibility of nerves
Original languageEnglish
Pages (from-to)771-780
JournalEuropean Journal of Anaesthesiology
Volume32
Issue number11
DOIs
Publication statusPublished - 2015

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