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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 kg m⁻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° or 180° abduction, elbow (E) 0° or 90° extension] and scans were performed proximally in the axilla, and additionally 5 cm 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 six-point 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°/E0°/D and S180°/E0°/P (P = 0.02). The ulnar nerve was more visible in position S180°/E 0°/P and D (P = 0.007). The greatest distance between artery and radial nerve was 7.4 ± 4.7 mm at an angle of 120 ± 14° in position S180°/E 0°/D., Conclusion: The visibility of the radial nerve was not improved by varying positions of the arm. S180°/E0° provided the best overall visibility and accessibility of nerves., Trial Registration: https://www.toetsingonline.nl/to/ccmo_search.nsf/Searchform?OpenForm Identifier: NL42116.018.12.

Background and Objectives: Use of ultrasound-guided regional anesthesia (UGRA) requires considerable training. An embedded electronic tutorial as an element of an ultrasound machine may help to identify sonoanatomy for novices. Therefore, we investigated whether an electronic tutorial could improve accuracy or speed of performance in identifying anatomical structures., Methods: Thirty-five novices in UGRA participated in a workshop on brachial plexus sonoanatomy. Following a lecture and training in handling of ultrasound machines and hand-eye coordination, participants were randomized in either group S, using a standard ultrasound machine, or group T, using the same type of machine with an onboard electronic tutorial. Each participant had to identify 27 anatomical structures from the brachial plexus of a volunteer. A correctly identified structure scored 1 point. An experienced observer noted scores and time required. Scores ± SD (in %) and times ± SD (in seconds) were compared between groups by analyses of independent-samples t test and analysis of variance. Influence of anesthesia experience was determined by multivariate analyses., Results: Group T scored significantly higher (16.8 ± 3.6 [62%] vs. 13.4 ± 4.4 [50%], P = 0.018), whereas time required was longer (1053 ± 244 vs. 740 ± 244 seconds, P = 0.001). Multivariate analysis revealed that experience had no influence on scores or time required. Examination of structures took more time in the beginning than at the end in group T., Conclusions: An electronic tutorial can help novices in UGRA identify anatomical structures. A significant increase in correct identifications was gained at the expense of significantly longer time required for this process. Increased time required may partly be related to unfamiliarity with the tutorial.

Background and Objectives: One of the advantages of ultrasound-guided peripheral nerve block is that visualization of local anesthetic spread allows for a reduction in dose. However, little is known about the effect of dose reduction on sensory and motor block duration. The purpose of the present study was to compare the duration of sensory and motor axillary brachial plexus block (ABPB) with 15 or 40 mL mepivacaine 1.5%., Methods: Thirty patients were randomly allocated to receive ultrasound-guided ABPB with either 15 (group 15 mL, n = 15) or 40 mL (group 40 mL, n = 15) mepivacaine 1.5%. Onset, efficacy, and duration of sensory and motor block were compared., Results: Two patients in group 15 mL needed an additional rescue block before surgery and were excluded from subsequent analysis. The overall median duration of sensory and motor block was significantly shorter in group 15 mL (225 [148-265] mins vs 271 [210-401] mins and 217 [144-250] mins vs 269 [210-401] mins, respectively; P < 0.01). Duration of sensory and motor block of individual nerves was significantly shorter in group 15 mL (20%-40% reduction for sensory and 18%-37% for motor block). Time to first request of postoperative analgesia was also significantly reduced in group 15 mL (163 [SD, 39] vs 235 [SD, 59] mins, respectively, P < 0.05). There were no differences in the other block characteristics., Conclusions: In ABPB with mepivacaine 1.5%, reducing the dose from 40 mL to 15 mL (62.5%) shortens the overall duration of sensory and motor block by approximately 17% to 19%, reduces sensory and motor block duration of individual nerves by 18% to 40%, and decreases the time to first request of postoperative analgesia by approximately 30%.