Effect of the use of dexmedetomidine as an adjuvant in peribulbar anesthesia in patients presented for vitreoretinal surgeries

Background
Dexmedetomidine, if used in combination with a local anesthetic mixture in peribulbar anesthesia, may alter the block characteristic. This research aimed to study the influence of adding dexmedetomidine to local anesthetics in the peribulbar block.
Methods
Sixty adult patients of both gender presented for vitreoretinal surgeries were enrolled in this prospective double-blinded study. They were randomly distributed into two equal groups. All the patients received peribulbar anesthesia with 10ml mixture composed of 4ml of plain bupivacaine 0.5%, 4ml of lidocaine 2 % containing 50IU hyaluronidase, and either 2ml of normal saline (Control group) or 20 μg dexmedetomidine in (Dexmedetomidine group). The onset, the duration, and quality of sensory and motor blockade and the perioperative sedation were recorded.
Results
As compared to the control group, dexmedetomidine when added to a local anesthetics in peribulbar block, significantly decreased the onset of anesthesia to 2.40 ± 1.50min, fastened the onset of the lid akinesia to 2.93 ± 2.07min and globe akinesia to 2.87 ± 1.96min, increased the duration of lid akinesia to 137.00 ± 17.94min and globe akinesia to 166.50 ± 21.34min, and increased the time of the first request for postoperative analgesia to 185.83 ± 30.80min (P< .05). Also, it significantly increased the level of patients sedation (P< .05).
Conclusion
A small dose of dexmedetomidine added to a local anesthetic mixture in peribulbar block improved the sensory and motor block criteria with increased level of patients sedation.