Comparison of dexmedetomidine and dexamethasone as adjuvants to ultra-sound guided interscalene block in arthroscopic shoulder surgery: A double-blinded randomized placebo-controlled study

Background: Interscalene block is one of the popular methods for decreasing pain and analgesic consumption after shoulder arthroscopic surgeries. Objectives: The objective is to compare the analgesic duration of effects of dexmedetomidine and dexamethasone as adjuvants to 0.5% ropivacaine in ultrasound-guided interscalene blocks for arthroscopic shoulder surgery in an ambulatory setting. Methods: In this randomized controlled trial, 117 adult patients candidate for ambulatory arthroscopic shoulder surgery under general anesthesia were divided into three groups to perform an ultra-sound guided interscalene block before the surgery. The ropivacaine (control) group received ropivacaine 0.5% 20 mL, group Dexamethasone received ropivacaine 0.5% 20 mL plus 4mg dexamethasone, and group dexmedetomidine received ropivacaine 0.5% 20 mL plus 75 mcg of dexmedetomidine. Time to return of sensory function, of motor function, of first pain sensation, amount of opioid medication consumed at 24 hours and 48 hours post-operatively were measured. Results: The 24-hour median (25th-75th percentile) opioid consumption in morphine equivalents was similar between groups 22.5 mg (10-30), 15 mg (0-30), and 15 mg (0-20.6) in the ropivacaine, dexmedetomidine, and dexamethasone groups, respectively (P = 0.130). The median (25th-75th percentile) 48 hours post-operatively, the median opioid consumption in morphine equivalents was 40 mg (25-67.5) in the ropivacaine group, 30 mg (22-50.6) in the dexamethasone group, and 52.5 mg (30-75) in the dexmedetomidine group (P = 0.278). The median 24-hour pain scores were 6 (5-8) in the ropivacaine control group, 7 (5.5-8) in the dexamethasone group, and 7 (4-9) in the dexmedetomidine group (P = 0.573). Conclusions: There was no statistical difference in opioid consumption at 24 and 48 hours post-operatively when comparing dexmedetomidine, dexamethasone, and no adjuvant. However, intraoperative opioid use was significantly lower with dexmedetomidine compared to dexamethasone and plain 0.5% ropivacaine. The safe side effect profile of dexmedetomidine makes it a reasonable alternative as an adjuvant for peripheral nerve blockade when dexamethasone use may be contraindicated.