Neostigmine and ketorolac as adjuvants to local anesthetic through peribulbar block in patients undergoing vitrectomy surgeries: A randomized controlled trial

This study aimed to assess the safety and efficacy of a neostigmine/ketorolac combination as an adjuvant to a low-dose local anesthetic mixture used for peribulbar block during vitrectomy surgeries. This double-blinded, parallel-group, randomized trial enrolled 50 adult patients of both genders who were American Society of Anesthesiologists physical status I or II and were scheduled for vitrectomy surgeries under regional anesthesia. All patients underwent peribulbar block through a single medial canthus injection technique. In the neostigmine and ketorolac (NK) group, 25 patients received a combined mixture of neostigmine (300 μg) and ketorolac (4 mg/ml) as adjuvants to a mixture of lidocaine (2%, 2.5 ml) and bupivacaine (0.5%, 3.5 ml) containing 75 units of hyaluronidase. The control (C) group received 1.5 ml of normal saline instead of neostigmine/ketorolac. The primary outcomes were the onsets and durations of both sensory and motor blocks. Secondary outcomes included the time to first analgesic dose, hemodynamics, adverse effects, and patient's and surgeon's satisfaction. The onsets of sensory and motor blocks were significantly shorter in the NK group compared to the C group. A significantly longer anesthesia and akinesia duration were observed in the NK group in comparison to the C group. The meantime to the first analgesic dose showed a significant difference between the NK and C groups. The NK group had a higher rate of adverse effects than the C group, though not reaching statistical significance. Patients' and surgeons' satisfactions were significantly higher in the NK group than the C group. In peribulbar anesthesia for vitrectomy surgery, adding neostigmine/ketorolac combination to a low-dose local anesthetic mixture was effective in reducing the onset and prolonging the duration of both sensory and motor block, and it was associated with higher safety and better patients' and surgeons' satisfaction.