Effect of adding dexmedetomidine to 0.75% ropivacaine in peribulbar block for vitreoretinal surgery

Background and Aims: Peribulbar anesthesia is suitable for vitreoretinal (VR) surgery. Dexmedetomidine has been used in peribulbar block (PBB) to improve akinesia and analgesia. We aimed to study the efficacy of adding dexmedetomidine to 0.75% Ropivacaine in PBB for VR surgery. The primary outcome was the requirement of block supplementation and secondary outcome was post-operative analgesic requirement. Material and Methods: 100 adult patients undergoing VR surgery were included in this prospective randomized double-blinded controlled study. The composition of the drug used for PBB in the 3 groups was Group R (8 ml of 0.75% Ropivacaine +0.5 ml normal saline (NS)), Group D25 (8 ml of 0.75% Ropivacaine +25 mu g Dexmedetomidine) and Group D50 (8 ml of 0.75% Ropivacaine +50 mu g Dexmedetomidine). Results: The groups were comparable in terms of patient demographics. The requirement for block supplementation was 16.7% in Group R (5/30), 12.5% in Group D25 (4/32) and 8.8% in group D50 (3/34) (P = 0.64).The mean time to first request for post-operative analgesia was432 +/- 362 min in Group R, 572 +/- 339 min in Group D25 and 614 +/- 394 min for Group D50 (P = 0.26). There was significant difference in the heart rate (P = 0.047), mean arterial pressure (P = 0.012) at 30 min and sedation (RASS) score at 15, 30, 60 (P < 0.001) and 120 (P = 0.019) min between the D50 and group R. Patients undergoing buckling procedures had significantly shorter time to request for analgesia (P = 0.003). Conclusion: Addition of dexmedetomidine does not offer advantage over 0.75% Ropivacaine in PBB for vitrectomy. Its benefit in more painful procedures like scleral buckle needs further validation.