Effects Magnesium Sulfate and Labetalol Infusion on Peripheral Perfusion and Pain in Nasal Surgeries

will receive IV bolus dose of 40mg/kg magnesium sulfate in 100 ml saline solution over ten minutes then continuous infusion of 10-15mg/kg/h will be titrated till achieve target mean arterial blood pressure (55-65 mmHg) and will be terminated by the end of surgery.

will receive IV bolus does of labetalol 0.25 mg/kg over ten minutes then continuous infusion of 0.5-1mg/kg/h will be titrated till achieve target mean arterial blood pressure (55-65 mmHg) and will be terminated by the end of surgery.