In this study, the minimum volume required for US-guided supraclavicular block in 50% of patients was 23 mL, and in 95% of patients was 42 mL. Under the present study conditions, the calculated volume of LA required for US-guided supraclavicular block does not seem to differ from the conventionally recommended volume required for supraclavicular blocks using non-US-based nerve localization techniques.

Purpose The success rate for infraclavicular brachial plexus block using nerve stimulation reportedly ranges from 60 to 80%. Ultrasound guidance may be associated with greater success. This study compared ultrasound guided infraclavicular block with a dual motor endpoint nerve stimulation technique. Methods One hundred three hand surgery patients were randomized to receive either ultrasound-guided (ultrasound group) or dual motor endpoint nerve stimulation (stimulation group) infraclavicular block using 2% lidocaine 15 mL and 0.5% bupivacaine 15 mL with epinephrine. Block success was defined as loss of sensation to pinprick in each of the radial, ulnar, median, and musculocutaneous nerve distributions when measured 20 min after block performance. Block performance time, readiness for surgery (no supplemental block, skin infiltration, or general anesthesia), and complications were also assessed.Results Patient characteristics were similar between groups. Success rate was 92% in the ultrasound group and 80% in the stimulation group (P = 0.18). Block performance time was shorter in the ultrasound group (median 5 min) compared with the stimulation group (median 10.5 min) (P \ 0.001). Paresthesiae were more frequent in the stimulation group (45%) than in the ultrasound group (6%) (P \ 0.001). After final injection, more patients were ready for surgery in the ultrasound group (85%) than in the stimulation group (65%) (P = 0.04). At 1 week postoperatively, complications were minor and transient and did not differ between groups. Conclusion There was no statistically significant difference in the success rate between ultrasound guidance and dual motor endpoint stimulation for infraclavicular block. However, ultrasound guidance shortens performance time and improves readiness for surgery compared with dual motor endpoint stimulation (Clinical Trial Registration Number: NCT00326261). RésuméObjectif Selon la litte´rature, le taux de re´ussite d'un bloc infraclaviculaire du plexus brachial re´alise´par stimulation nerveuse se situe entre 60 % et 80 %. L'e´choguidage pourrait eˆtre associe´a`un taux de re´ussite plus e´leve´. Cette e´tude a compare´un bloc infraclaviculaire re´alise´par e´choguidage a`une technique de double stimulation nerveuse des extre´mite´s motrices. Méthode Cent-trois patients devant subir une chirurgie de la main ont e´te´randomise´s à recevoir un bloc infraclaviculaire re´alise´soit par e´choguidage (groupe e´choguidage) ou par double stimulation nerveuse des extre´mite´s motrices (groupe stimulation) a`l'aide de 15 mL de lidocaı¨ne 2 % et de 15 mL de bupivacaı¨ne 0,5 % avec e´pine´phrine. La re´ussite du bloc a e´te´de´finie en tant que la