Comparative Study Between Dexmedetomidine & Neostigmine as an Adjuvant to Local Anesthetic Mixture in Peribulbar Block in Vitreoretinal Surgeries

Overview

The majority of patients undergoing ophthalmic surgeries are elderly, with multiple chronic diseases, with increased risk of morbidity and mortality under general anesthesia. Peribulbar anesthesia is widely practiced now as a first-choice local block for ophthalmic surgeries. Dexmedetomidine is a highly selective alpha-2 adrenoceptor. It increases central and peripheral nerve blockade and when added to local anesthetic as an adjuvant, it will provide better anesthetic quality as well as prolongation of postoperative analgesia . Neostigmine is a parasympathomimetic drug that increase the level of acetylecholine at peripheral muscarinic receptors present in the peripheral nerve endings . Many researches examined the analgesic effects of peripherally administered neostigmine as in intravenous regional anesthesia reporting that addition of neostigmine to the local anesthetic solution accelerated the onset of anesthesia \& prolong duration .

81 participants divided into three groups 27 patient in each group with inclusion criteria : * Patients aged from 21 to 60 years. * Patients ASA I to II undergoing Vitreoretinal Surgeries. * Patient with axial globe length below 26 mm. * Patients consented with Local anesthesia. The three groups: group I : will receive Peribulbar anesthesia block via 25G needle is inserted transcutaneously through the inferotemporal approach at the junction between the medial two third and the lateral third of the lower orbital margin in such a way the bevel is facing the globe and the tip towards the floor of the orbit until the needle passes through the orbital septum it is directed then posteriorly tangential to the floor of the orbit for 25mm length at which the 8 ml local anesthetic mixture is injected ( 4 ml of bupivacaine + 3 ml of mixture of Lidocaine \& Hyaluronidase +1ml of Dexmedetomidine equivalent to 25 mcg). Ocular compression is applied for 5 minutes by Honan intraocular pressure IOP reducer adjusted at 20mmHg. Group II : Will recieve ( 4 ml of bupivacaine + 3 ml of mixture of Lidocaine \& Hyaluronidase +1ml of Neostigmine equivalent to 0.5 mg) Group III : ( 4 ml of bupivacaine + 3 ml of mixture of Lidocaine \& Hyaluronidase +1ml Normal Saline 0.9%)