Intertruncal versus classical approach to the ultrasound-guided supraclavicular brachial plexus block for upper extremity surgery: study protocol for a randomized non-inferiority trial

BACKGROUND: Ultrasound-guided intertruncal approach (IA) to the supraclavicular block (SB) is recently proposed as a new approach for local anesthetic (LA) injection in terms of the classical approach (CA) at the level of the first rib. The CA-SB has been proven to result in satisfying sensorimotor block, but associate with a high risk of intraneural injection. The aim of this randomized non-inferiority study is to explore whether IA-SB can obtain similar block dynamics, as the CA-SB, but avoiding an intraneural injection during the whole nerve block procedure. METHODS: The total 122 patients undergoing elective upper extremity surgery will be randomly allocated to receive either an IA-SB or a CA-SB using a double-injection (DI) technique. In the IA-SB group, a portion of LA (15 mL) is injected accurately to the intertruncal plane between the middle and lower trunks under real-time ultrasound guidance; then, the remaining volume (10 mL) is carefully distributed to the other intertruncal plane between the upper and middle trunks. In the CA-SB group, the DI technique will be carried out as described in Tran’s study. The primary outcome is the percentage of patients with a complete sensory blockade at 20 min with a predefined non-inferiority margin of − 5%. The secondary outcomes include the sensory-motor blockade of all 4 terminal nerves, onset times of the individual nerves within 30 min, block-related variables, and adverse events. DISCUSSION: The results will provide sensory-motor blockade-related parameters and safety of the ultrasound-guided intertruncal approach to the supraclavicular block, thereby promoting clinical practice. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2000040199. Registered on 25 November 2020 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06029-x.