The Efficacy of Dexmedetomidine versus Dexamethasone as Additives to Lidocaine 2 % for Peribulbar Block in Vitreoretinal Surgery: A Randomized Controlled Trial

Background: Dexmedetomidine (DEX) and dexamethasone (DEXA) are increasingly utilized as anesthetic adjuvant to improve block quality and extend postoperative analgesia. Objective: This research aimed to evaluate the efficacy and safety of DEX and DEXA as lidocaine 2%-adjuvants in patients undergoing elective vitreoretinal (VR) surgery under peribulbar block (PBB). Patients and methods: This randomized, triple-blind trial enrolled 90 patients (18–70 years, both sexes) undergoing elective VR surgery under PBB. Patients were randomized into three equal groups and received 5 mL of 2% lidocaine plus either 1 mL saline (control), DEX 0.5 μg/kg diluted to 1 mL (DEX), or DEXA 4 mg (1 mL) (DEXA). Results: DEX and DEXA significantly reduced sensory and motor block onset times (p<0.05), with the fastest onset in the DEX group. Sensory and motor block duration and postoperative analgesia were significantly prolonged in both adjuvant groups (p<0.05), with the longest duration in the DEXA group (p<0.05). Sedation scores were highest in the DEX group (RSS 2–3; p<0.001). Bradycardia occurred in the DEX group (p=0.03), while hypotension was not statistically significant. Intraoperatively, heart rate and mean arterial pressure decreased significantly in the DEX group relative to the other groups. Conclusions: DEXA was superior to DEX as a lidocaine adjuvant for PBB in vitreoretinal surgery, providing longer sensory and motor block duration and postoperative analgesia with minimal hemodynamic effects, whereas DEX offered faster onset and sedation but may cause mild bradycardia and hypotension. ？