Intraoperative Infusion of Either Lidocaine or Dexmedetomidine on Regional Cerebral Oxygen Saturation and Postoperative Delirium in Elderly Patients Undergoing Abdominal Surgeries

Patients will receive an IV bolus (50 ml) of lidocaine (1mg/kg) diluted with saline over 10 min before induction of anesthesia. This will be followed by intraoperative lidocaine infusion in a dose of 1.5mg /kg/hr till the end of surgery.

Patients will receive an IV bolus (50 ml) of dexmedetomidine in dose 0.5 μg/kg over 10 min before induction of anesthesia. This will be followed by intraoperative dexmedetomidine infusion in a dose of 0.3 μg/kg/hr till the end of surgery.