Supraclavicular upper trunk block versus interscalene block for clavicle surgery: A prospective observational comparison of block onset and postoperative analgesia

• Author Details:   
• Archana B N
• Aswin M Ullas
• Shivakumar G

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Background: Effective postoperative analgesia for clavicle surgery is challenging due to the region's complex innervation. The interscalene block (ISB) is a common approach but is associated with phrenic nerve palsy. The supraclavicular upper trunk (SCUT) block is a more targeted alternative that may preserve diaphragmatic function. This study aimed to compare the block onset characteristics and postoperative analgesic efficacy of supraclavicular upper trunk block versus interscalene block in patients undergoing clavicle surgery.

Materials and Methods: In this prospective, randomized controlled trial, 70 patients undergoing elective clavicle surgery were allocated to receive either an ultrasound-guided ISB (n=35) with 25 ml of local anaesthetic (0.23% bupivacaine and 0.92% lidocaine with 8 mg dexamethasone) or an SCUT block (n=35) with 10 ml of local anaesthetic (0.2% bupivacaine and 0.8% lidocaine with 8 mg dexamethasone). The primary outcomes were the onset time of sensory and motor blockade. The secondary outcomes included the duration of analgesia (time to first rescue analgesic request for a VAS score ≥4) and pain scores (VAS) monitored for 36 hours.

Results: The onset of sensory blockade was significantly faster in the ISB group (3.48 ± 0.92 minutes) compared to the SCUT group (4.84 ± 1.03 minutes; p < 0.0001). Motor blockade onset was also faster with ISB (5.52 ± 1.01 minutes) than with SCUT block (9.00 ± 1.00 minutes; p < 0.0001). The duration of analgesia was significantly longer in the ISB group (11.24 ± 1.80 hours) compared to the SCUT group (10.08 ± 1.32 hours; p = 0.013). No significant adverse effects were reported in either group.

Conclusion: The interscalene brachial plexus block provides a faster onset of sensory and motor blockade and a longer duration of analgesia. In contrast, the supraclavicular upper trunk block achieves effective postoperative analgesia with a substantially reduced local anaesthetic volume. The supraclavicular upper trunk block thus represents a valuable alternative for clavicle surgery, where its targeted approach may lower the risk of complications such as phrenic nerve palsy, offering a favorable safety profile without compromising analgesic quality.