A prospective randomized controlled study comparing intrathecal dexmedetomidine and intrathecal fentanyl for the prevention of post-spinal anaesthesia shivering in endoscopic urosurgical cases.

Spinal anaesthesia is a common technique for uroscopic procedures. Shivering is a common side effect after spinal anaesthesia due to inhibition of tonic vasoconstriction thereby causing redistribution of heat from trunk to peripheral areas. It is  more common in endoscopic surgeries due to absorption of large amount of cold irrigating fluids. Shivering is an involuntary , spontaneous and repetitive activity of the muscles. It leads to patient distress, impairment in monitoring , increased oxygen consumption and  carbon dioxide production. Dexmedetomidine is a highly selective alpha 2 adrenorecptor agonist which decreases the sympathetic tone. Side effects include hypotension , bradycardia, drymouth and nausea. fentanyl is a phenylpiperidine derivative synthetic opioid. It ha effect on spinal afferent thermal inputs and thermoregulator at spinal cord. side effects include hypotension, bradycardia, urinary retention, pruritis, nausea and vomiting. In this study we will compare the incidence and grades of shivering , duration of sensory block , hypotension, bradycardia, nausea and vomiting between 3 groups group D receiving intrathecal dexmedetomidine , group F receiving intrathecal fentanyl and group C receiving normal saline as adjuvants with 12.5- 15 mg of 0.5% heavy bupivacaine.