Comparison of Dexmedetomidine and Dexamethasone as Adjuvants to Ropivacaine in Ultrasound-Guided Supraclavicular Brachial Plexus Block: A Prospective Randomised Double-Blind Comparative Trial

Background: Dexmedetomidine and dexamethasone are commonly used as adjuvants to local anaesthetics for prolonging peripheral nerve block, but their comparative efficacy and adverse-effect profiles remain inconsistent across studies. The aim is to compare the efficacy and safety of dexmedetomidine and dexamethasone as adjuvants to ropivacaine in ultrasound-guided supraclavicular brachial plexus block. Material and Methods: In this prospective, randomised, double-blind comparative trial, 200 adults aged 18–65 years with ASA physical status I–II undergoing elective upper-limb surgery were randomised equally to receive 0.5% ropivacaine with dexmedetomidine 1 µg/kg (Group D) or dexamethasone 8 mg (Group X). Sensory and motor block characteristics, postoperative NRS pain scores, time to first rescue analgesia, cumulative 24-hour tramadol consumption, haemodynamic parameters, patient satisfaction, and adverse events were evaluated. Results: Sensory and motor block onset were faster in Group D than Group X (8.3 ± 1.5 vs 9.5 ± 1.6 minutes and 11.7 ± 1.8 vs 13.1 ± 1.9 minutes, respectively; both P<0.001). Sensory and motor block durations were longer with dexmedetomidine (825 ± 95 vs 718 ± 92 minutes and 682 ± 86 vs 604 ± 82 minutes; both P<0.001). Time to first rescue analgesia was prolonged (1310 ± 150 vs 1102 ± 145 minutes; P<0.001), while cumulative 24-hour tramadol consumption was lower (57.4 ± 14.8 vs 73.1 ± 16.5 mg; P<0.001). Group D also had lower postoperative NRS scores and higher patient satisfaction. Mean arterial pressure and oxygen saturation were comparable, although heart rate was modestly lower with dexmedetomidine. Sedation was more frequent in Group D (16.0% vs 3.0%; P=0.003); other adverse events were comparable. Conclusion: Under the study protocol, dexmedetomidine provided faster onset, longer sensory and motor blockade, prolonged postoperative analgesia, and lower rescue analgesic requirement than dexamethasone, but with a higher incidence of sedation.

Keywords: Dexmedetomidine; dexamethasone; ropivacaine; supraclavicular brachial plexus block; ultrasound guidance; postoperative analgesia.