Efficacy and safety of Sodium Bicarbonate, Magnesium Sulfate, and Hyaluronidase as Additives to Peribulbar Anesthesia in Vitreoretinal Surgeries: A Randomized Double-Blind Comparative Study

Abstract

Background: The peribulbar block represents the gold standard for vitreoretinal surgery in adults. However, a delayed start of globe akinesia and corneal anesthesia, a brief duration of analgesia, and a frequent requirement for block replacement restrict the utilization of local anesthetic drug mixes for peribulbar anesthesia. The use of adjuvants can improve the effectiveness of local anesthetic.
Objective: To evaluate the safety and efficacy of adding hyaluronidase, sodium bicarbonate, and magnesium sulfate to the local anesthetic mixture for peribulbar anesthesia during vitreoretinal surgery.
Methods: This randomized, double-blind, parallel-group clinical trial enrolled 75 patients scheduled for vitreoretinal surgery. Eligible patients were randomized to one of three groups of 25 patients each. All patients received a peribulbar local anesthetic injection in addition to 1 mL of hyaluronidase, 1 mL of sodium bicarbonate 8.4%, and 75 mg of magnesium sulfate in the hyaluronidase, bicarbonate, and magnesium groups, respectively.
Results: At 5 minutes after block, complete globe akinesia was evident in all patients in the hyaluronidase and magnesium groups (100% each), which was significantly higher than in the bicarbonate group (56.0%). The onset of eyelid akinesia was rapid in both the hyaluronidase and magnesium groups, occurring with almost equal frequency 3 minutes after block (52% and 56%, respectively; P=0.777). In contrast, only 20% of the bicarbonate group had lid akinesia at 3 minutes, a significantly lower incidence than that observed in the hyaluronidase (P=0.018) and magnesium (P=0.009) groups. The onset of globe anesthesia was rapid in the hyaluronidase group, followed by the magnesium group and then the bicarbonate group, with a statistically significant difference. At the 5-minute post-block time point, intraocular pressure was significantly lower in the hyaluronidase and magnesium groups than in the bicarbonate group (18.4±2.0, 18.6±2.0, and 20.5±2.3, respectively).
Conclusion: Hyaluronidase and magnesium sulfate were more effective than sodium bicarbonate. The efficacy of hyaluronidase and magnesium sulfate in improving the onset of lid and globe akinesia and lowering intraocular pressure was comparable. However, the use of sodium bicarbonate as an adjuvant was associated with a high incidence of complications.