Effects of double vs triple injection on block dynamics for ultrasound-guided intertruncal approach to the supraclavicular brachial plexus block in patients undergoing upper limb arteriovenous access surgery: study protocol for a double-blinded, randomized controlled trial

BACKGROUND: Ultrasound-guided intertruncal approach (IA) has been proposed to be an alternative and promising approach to the supraclavicular block (SCB), in which double injection (DI) of local anesthetics (LA) is sequentially administered between intertruncal planes. We would like to apply a refined injection technique, named triple injection (TI) technique, based on the 3 separate compartments visualized by ultrasound. The aim of this study is to compare the percentage of patients with complete sensory blockade at 20 min of DI vs TI technique, when they are applied in patients undergoing upper limb arteriovenous access surgery. METHODS: This study is a prospective parallel-group randomized controlled trial. A total of 86 end-stage renal disease patients will be randomly allocated to receive IA-SCB using either DI or TI technique with identical LA (0.5% ropivacaine 24 mL). The primary outcome is the percentage of patients with complete sensory blockade of all 4 terminal nerves (median, ulnar, radial, and musculocutaneous nerves) of the brachial plexus measured at 20 min after injection. The secondary outcomes will consist of the sensory or motor blockade of all individual nerves, onset times, performance time, diaphragmatic paralysis, surgical anesthesia, and adverse events. DISCUSSION: It is expected that ultrasound-guided IA-SCB with the TI technique results in better block dynamic in patients undergoing upper limb arteriovenous access surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100045075.