Diaphragm-sparing efficacy of subparaneural upper trunk block for arthroscopic shoulder surgery

BACKGROUND Inter-scalene block (ISB) is associated with an inevitable risk of hemi-diaphragmatic paresis (HDP). To reduce the risk of HDP, an upper trunk block (UTB) has been proposed at the brachial plexus division level. OBJECTIVE We hypothesised that UTB would be associated with a lower incidence of HDP than ISB while providing sufficient analgesia following arthroscopic shoulder surgery. DESIGN Randomised controlled trial. SETTING A tertiary teaching hospital. PATIENTS Seventy patients aged 20 to 80 years undergoing arthroscopic rotator cuff repair. INTERVENTION Ultrasound-guided ISB or UTB was performed with 5 ml 0.75% ropivacaine. MAIN OUTCOME MEASURES The primary outcome was the incidence of complete HDP, assessed by diaphragm excursion using ultrasound, defined as a decrease to 25% or less of baseline or occurrence of paradoxical movement. Postoperative pulmonary function change, pain scores, opioid consumption and pain-related outcomes were the secondary outcomes. RESULTS The UTB group had a significantly lower incidence of complete HDP than the ISB group [5.9% (2/34) vs. 41.7% (15/36); absolute difference, 35.8%; 95% confidence interval (CI), 17.8 to 53.7%; P < 0.001]. The postblockade decline in pulmonary function was more pronounced in the ISB group than that in the UTB group. The pain score at 1 h postoperatively was not significantly different between the groups (ISB vs. UTB group: median 0 vs. 1; median difference, −1; 95% CI, −2 to 0.5). No significant difference was observed in any other secondary outcomes. CONCLUSION UTB was associated with a lower incidence of HDP compared with ISB while providing excellent analgesia in arthroscopic shoulder surgery. TRIAL REGISTRATION Clinical Trial Registry of Korea (https://cris.nih.go.kr) identifier: KCT0007002. IRB NUMBER Chungnam National University Hospital Institutional Review Board No. 2021-12-069.