Acta Anaesthesiol Scand 2006; 50: 678–684 Printed in Singapore. All rights reserved Copyright # Acta Anaesthesiol Scand 2006 ACTA ANAESTHESIOLOGICA SCANDINAVICA doi: 10.1111/j.1399-6576.2006.01042.x Ultrasound guidance improves the success rate of a perivascular axillary plexus block B. D. SITES, M. L. BEACH, B. C. SPENCE, C. W. WILEY, J. SHIFFRIN, G. S. HARTMAN and J. D. GALLAGHER Departments of Anesthesiology and Orthopedic Surgery, Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA Background: Traditional approaches to performing brachial plexus blocks via the axillary approach have varying success rates. The main objective of this study was to evaluate if a specific technique of ultrasound guidance could improve the success of axillary blocks in comparison to a two injection transarterial technique. Methods: Fifty-six ASA physical status I–III patients presenting for elective hand surgery were prospectively randomized to receive an axillary block performed by either a transarterial technique (Group TA) or an ultrasound-guided perivascular approach (Group US). Both groups received a total of 30 ml of 1.5% lidocaine (225 mg) with 5 mg/ml epinephrine. Patients were then evaluated for block onset in specific nerve distributions and whether or not the block acted as a surgical anesthetic. Results: Group TA sustained more failures defined as conversion to general anesthesia or the inability to localize the artery [Group TA eight patients (29%) vs. Group US in which 0 patients required conversion to general anesthesia (0%) P < 0.01]. Group US demonstrated a reduction in performance times vs. Group TA (7.9  3.9 min vs. 11.1  5.7 min, P < 0.05). By 30 min post- injection, there were no significant differences between groups TA and US in terms of the proportion of patients demonstrating a complete motor or sensory loss. Conclusion: Ultrasonographic guidance improves the overall success rate of axillary blocks in comparison to a transarterial technique. Accepted for publication 15 February 2006 Key words: axillary block; ultrasound; upper extremity; brachial plexus. # Acta Anaesthesiologica Scandinavica 50 (2006) H ISTORICALLY, axillary blocks have a wide range of reported success rates. Success rates range from 50% to 100% depending on the technique used, the level of experience of the operator, and the individual definitions of success (1–5). Failures are usually attributed to malposition of local anesthetic or septa- tion of the brachial plexus sheath (6). Therefore, it is reasonable to search for alternative techniques that may improve on the accuracy of local anesthetic deposition, and, hence, on overall success rates. Over the past 5 years, ultrasound has become popular with anesthesiologists performing regional anesthesia (7,8). Proponents of the use of ultrasound to facilitate peripheral regional anesthesia suggest that this technology may improve success rates, simplify the technical challenges, decrease perform- ance times, and reduce complications (9). The critics of ultrasound guidance cite the lack of con- trolled trials supporting its use, the expense of high- resolution equipment, and the sometimes equivocal nature of the images (10). Despite the rapid growth of ultrasound-guided techniques, the transarterial approach to the axillary brachial plexus is still commonly performed (11). Indeed, 85% of American Anesthesiology residency programs include training in transarterial regional anesthesia (12). We sought to conduct a randomized and controlled trial comparing a technique of an ultrasound-guided perivascular axillary block with a transarterial tech- nique. Our hypothesis in this study was that ultra- sound guidance would improve the overall success rate of an axillary plexus block in comparison to a transarterial technique. Methods This single-blinded, prospective, randomized and controlled trial was reviewed and approved by the These data were presented as an abstract for the American Society of Anesthesiologists Annual Meeting, October 2005. 678