comparison of adding dexmedetomidine versus fentanyl to Intrathecal local anesthetic aiming at prevention or lowering the incidence of rebound pain in patients undergoing open surgeries under spinal anesthesia. a Randomized Controlled Trial.

Spinal anesthesia is a safe and reliable method of anesthesia for abdominal and lower limb surgery, with the advantages of rapid onset of action, economical and easy to administer, and a relatively low side effects rate and shorter post-anesthesia care unit stay. Regional anesthesia (RA) techniques have been shown to reduce perioperative opioid requirements, postoperative length of stay, and positively impact long-term outcomes such as the risk of persistent postsurgical pain (PPSP), morbidity, and mortality. It has been found that many drugs, such as opioids α2 adrenergic agonists can be used as adjuvants for intrathecal local anesthetics to improve the quality of spinal anesthesia. Rebound pain is a recently introduced term used to describe acute postoperative pain occurring after regression of the sensory block associated with regional anesthesia. It has been observed to occur after both peripheral nerve block and neuraxial anesthesia. Essential characteristics of rebound pain are that it is acute postoperative pain, ensues following resolution of PNB or neuraxial block, and is clinically significant, either with regard to the intensity of pain or the impact on psychological well-being, quality of recovery, and activities of daily living. This study aims to assess the efficacy of addition of dexmedetomidine versus fentanyl to the local anesthetic for prevention of rebound pain after open surgeries performed under spinal anesthesia. We hypothesize that the intrathecal dexmedetomidine administration would decrease the incidence of rebound pain. Incidence of intraoperative hypotension, bradycardia, nausea, vomiting and pruritus compared between fentanyl and dexmedetomidine groups. Severity of rebound pain score (RPS), duration of the sensory and motor blocks, deepest level of sedation, patient satisfaction from pain control and meperidine requirement all compared between two groups.