A Randomized Double-Blind Trial Comparing the Efficacy of Dexamethasone vs. Clonidine as an Adjunct to Ropivacaine in Ultrasound Guided Continuous Interscalene Block for Arthroscopic Shoulder Surgery

Background: Ultrasound-Guided Continuous Interscalene Block (USGCISB) decreases postoperative morbidity following arthroscopic shoulder surgery. Both dexamethasone and clonidine have been shown to prolong the duration of analgesia when added with ropivacaine in peripheral nerve blocks. However, there is no head-to-head comparison between dexamethasone and clonidine as an adjuvant using USG-CISB. Methods: In this randomized double-blinded controlled trial, 60 ASA grade 1-2 patients, 18-65 years, scheduled for arthroscopic shoulder surgery under general Anaesthesia following USG-CISB with perineural catheter using 30 ml of 0.5% ropivacaine were randomly allocated to Group 1 (adjunct dexamethasone 8 mg) or Group 2 (adjunct clonidine 150 μg). Primary outcome was duration of postoperative analgesia, as measured (in min) from the achievement of adequate sensory block till the first bolus of 0.2% ropivacaine by patient controlled regional analgesia. Secondary outcomes were measures of the pain ratings, total postoperative analgesic consumption, patient satisfaction, and adverse effects over 48h postoperatively. Results: The median duration of analgesia in Group 1 was significantly longer than Group 2 (1432 min vs. 751 min; P < 0.001). Median total postoperative analgesic consumption in Group 1 was significantly less than Group 2 (84 ml vs. 120 ml; P < 0.001). Median patient satisfaction score in Group 1 was significantly more than Group 2 (90 vs. 84; P = 0.001). Postoperative adverse effects were few and comparable. Conclusion: Compared to clonidine, dexamethasone significantly prolonged the duration of analgesia, decreased postoperative analgesic consumption, and increased patient satisfaction following USG-CISB when used as an adjunct to ropivacaine for arthroscopic shoulder surgery.