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

Inclusion Criteria: * Age ≥ 65years old. * Both sexes. * Physical status classification of II - III according to the American Society of Anesthesiologists (ASA). * Undergo elective non-cardiac surgeries. Exclusion Criteria: * History of mental illness, neurological illness, or scoring less than 8 using the abbreviated mental test (AMT) before operation. * Severe hearing or visual impairment that may interfere with communication. * Severe renal or hepatic dysfunction. * Patients on central nervous system (CNS) medications (antipsychotics, anticonvulsants, antiparkinsonian, antidepressants). * Contraindications to lidocaine or dexmedetomidine \[e.g., allergy, severe bradycardia, atrioventricular (AV) block\].