Comparison of incidence of hemidiaphragmatic paresis in conventional volume with low volume Superior Trunk block in patients undergoing arthroscopic shoulder surgery

This prospective randomized study compares the incidence of hemidiaphragmatic paresis and analgesic efficacy between low volume 4 mL and conventional volume 10 mL of 0.5 percent ropivacaine in ultrasound guided superior trunk block for arthroscopic shoulder surgery. Arthroscopic Bankart repair is associated with significant postoperative pain, and while interscalene brachial plexus block is effective, it frequently causes ipsilateral hemidiaphragmatic paresis, limiting use in patients with respiratory compromise. Superior trunk block targets C5 and C6 nerve roots to provide effective analgesia with potentially less phrenic nerve involvement, but the optimal local anesthetic volume is unclear. Seventy ASA I to II patients aged 18 to 65 years will be allocated to two groups receiving either 4 mL or 10 mL ropivacaine. Primary outcome is the incidence of hemidiaphragmatic paresis assessed by ultrasound diaphragmatic excursion. Secondary outcomes include pulmonary function tests, numeric rating scale pain scores, intraoperative fentanyl use, time to first rescue analgesia, postoperative tramadol use, and patient satisfaction. The study aims to determine the smallest effective volume that provides adequate analgesia while preserving respiratory function.