Lidocaine Infusion Versus Magnesium Infusion in Decreasing Fentanyl Requirements in Endoscopic Sinus Surgeries

25ml of lidocaine hydrochloride 2% will be added to 25 ml of standard saline 0.9% solution in a 50ml syringe to be infused via a syringe pump. The resultant concentration will be 10mg/ml. According to the calculated study drug dose, each patient will receive 0.2ml/kg/h

a 50ml syringe will be filled with magnesium sulfate solution (100mg/ml) to be infused via a syringe pump. According to the calculated study drug dose, each patient will receive 0.2ml/kg/h

a 50ml syringe will be filled with a standard saline 0.9% solution to be infused via a syringe pump. Each patient will receive 0.2ml/kg/h