Intranasal Versus Intravenous Dexmedetomidine for Hypotensive Anesthesia in FESS

45 -60 min before the operation, patients will receive dose of dexmedetomidine 1microgram/kg diluted in 10ml 0.9% saline administered to each naris as drops + infusion saline

patients will receive loading dose of dexmedetomidine 1 µg/kg diluted in 10ml 0.9% saline infused over 45- 60 min before induction of anesthesia, followed by continuous infusion of (0.4 µ g/kg/h) + intranasal saline.