A Randomized Comparative Study to Evaluate the Effects and Safety of Intrathecal Fentanyl Versus Intrathecal Dexmedetomidine as Adjuvants to 0.5 Percent Hyperbaric Levobupivacaine in Patients Undergoing Infraumbilical Surgeries Under Spinal Anaesthesia

This randomized , double blind , pospective study is designed to evaluate the comparative effects and safety of adding fentanyl or dexmedetomidine to 0.5% hyperbaric levobupivacaine for spinal anaesthesia in patients undergoing infraumbilical surgeries . Spinal Anaesthesia involves the administration of local anesthetic directly into cerebrospinal fluid within the sub arachnoid space , producing reversible sensory and motor blockade . The distribution and height of the block are influenced by the density of the anesthetic solution relative to CSF, as well as patient positioning . hyperbaric solutions , creating by adding dextrose to levobupivacaine , are denser than CSF, allowing more predictable spread of anesthesia and better control over the block level. Levobupivacaine, the S enantiomer of bupivacaine , offers similar anesthetic potency with reduced cardiotoxicity and neurotoxicity compared to racemic bupivacaine , making it a safer option for spinal anaesthesia. To enhance the quality and duration of anesthesia, adjuvants like fentanyl , a lipophilic opioid, and dexmedetomidine , a selective alpha2- adrenergic agonist, can be added.Fentanyl provides rapid onset analgesia with minimal motor block, while dexmedetomidine prolongs sensory and motor blockade and may improve postoperative analgesia with stable hemodynamics. In this study , patient will receive either 5mcg demedetomidine or 25mcg fentanyl added to 3ml of 0.5percent hyperbaric levobupivacaine. The primary outcomes include the onset , duration and highest level of sensory block, as well as the degree and duration of motor block, while secondary outcomes include hemodynamic changes. The study aims to determine the superior adjuvant for providing safe, effective and prolonged spinal anaesthesia in infraumbilical surgeries