Effects of the Costoclavicular Block Versus Interscalene Block in Patients Undergoing Arthroscopic Shoulder Surgery under Monitored Anesthesia Care: a Randomized, Prospective, Non-Inferiority Study

Background Recent studies have reported that costoclavicular blocks (CCBs) can consistently block almost all branches of the brachial plexus while sparing the phrenic nerve and provide effective analgesia after shoulder surgery. We aimed to compare the efficacy of the CCB with that of the interscalene block (ISB) as the sole blocking technique for shoulder surgery. Methods A total of 212 patients undergoing elective arthroscopic shoulder surgery were randomized to receive an ISB or CCB based on a non-inferiority design. All patients received titration sedation with propofol under monitored anesthesia during surgery. The primary outcomes were the proportion of patients with complete motor blockade of the suprascapular nerve (SSN) and incidence of hemidiaphragmatic paralysis (HDP). The secondary outcomes included block-related variables, complications, and postoperative pain scores. Results The proportion of patients with complete motor blockade of the SSN at 20 min between the CCB and ISB groups (53% vs. 66%) exceeded the predefined non-inferiority margin of −5%, but was comparable at 30 min (87% vs. 91%). The CCB resulted in a significantly lower incidence of HDP (7.55% vs. 92.45%), Horner’s syndrome (0% vs. 18.87%), and dyspnea (0% vs. 10.38%) than the ISB. None of the patients experienced failed blocks or required conversion to general anesthesia. Pain scores were comparable between the groups. Conclusions Ultrasound-guided CCBs may be comparable to ISBs, with fewer unfavorable complications in patients with impaired lung function undergoing arthroscopic shoulder surgery.