Ultrasound-guided anterior suprascapular nerve block versus interscalene brachial plexus block for arthroscopic shoulder surgery: A randomised controlled study

Background and Aims: The interscalene brachial plexus block (ISB) affects the phrenic nerve, resulting in hemi-diaphragmatic paresis (HDP) and, possibly, respiratory distress. Suprascapular nerve block via an anterior approach (SSB-A) is performed more distally at the level of the trunk of the brachial plexus and, thus, may spare the phrenic nerve. This study compares the analgesic efficacy and decline of hemi-diaphragmatic excursion (HDE) following ultrasound (US)-guided SSB-A versus ISB for arthroscopic shoulder surgery. Methods: This study was conducted on 60 adult participants undergoing arthroscopic shoulder surgery under general anaesthesia. Both US-guided SSB-A (n = 30) and ISB (n = 30) were performed with a combination of 10 ml bupivacaine (0.5%) and 4 mg dexamethasone. The primary objective was to compare the duration of analgesia (time to first rescue analgesia), and secondary objectives were to compare 24-h postoperative numerical rating scale (NRS) scores, 24-h morphine consumption and post block change in HDE, and pulmonary function tests (PFTs) between the two groups. For analysing intergroup differences of NRS, HDE and PFT; Pearson's Chi-squared test or Fisher's exact test, unpaired t test, and Mann-Whitney U test were used. For intragroup differences, paired t test was used. A P value <0.05 was considered significant. Results: The duration of analgesia (mean +/- Standard Deviation) was similar in two groups (SSB-A = 1,345 +/- 182 min, ISB = 1,375 +/- 156 min; P = 0.8). The reduction in HDE was significantly greater in the ISB group (44%) than in the SSB-A group (10%). Pulmonary function was better preserved in the SSB-A group. Conclusion: Compared to ISB, SSB-A has a similar analgesic efficacy for arthroscopic shoulder surgeries, but it is superior in preserving diaphragmatic function and pulmonary function.