Postoperative Cognitive Dysfunction (POCD), is a subtle decline in cognitive function characterized by impairment of memory and reduced ability to concentrate in elderly patients exposed to general anaesthesia. This prospective study aims to compare incidence and severity of POCD in two groups of patients. Group P receiving Intravenous Propofol and Inhalational anesthetic Sevoflurane. Group D receiving Intravenous Dexmedetomidine and Inhalational anesthetic Sevoflurane, Neuropsychological Test will be performed 24 hours before surgery and on postoperative day 3 and day 7.

The adult patients posted for major surgery under general anesthesia will be included in the study, patients will be allotted randomly to either Group P (Propofol) or Group D (Dexmedetomidine). In the Operation Room (OR) monitoring Electrocardiography (ECG), Pulse Oximetry (SPO2), Noninvasive Blood Pressure (NIBP), End tidal Carbon di oxide (ETCO2) and Bispectral Index (BIS) Covidien, will be attached to all patients. In both groups Anesthesia will be induced with Fentanyl 1mcg /kg-1, Morphine 0.1mg/kg-1, Propofol 1-1.5mg /kg1- and neuromuscular blocking agent Atracurium 0.5 mg/kg-1. Oral Cuffed Endotracheal Tube (ETT) will be placed in the trachea. Anaesthesia will be maintained controlled ventilation , intermittent fentanyl boluses 20 mcg and in Group P with medicated Air/Oxygen (O2) with Fractional Inspired Oxygen (FiO2 50%), Sevoflurane and Propofol Infusion to maintain BIS between 40-60. In Group D anesthesia will be maintained with Medicated Air/Oxygen (FiO2 50%), Sevoflurane and Dexmedetomidine infusion to maintain BIS between 40-60. Intraoperatively monitoring of vitals, BIS numerical value, Minimum Alveolar Concentration (MAC) Value for Sevoflurane, Expired concentration of Sevoflurane and rate of infusion of Propofol/Dexmedetomidine will be noted every 30 minutes. Intraoperative decrease in Mean Arterial Pressure (MAP) < 60 mmHg, Heart rate (HR) < 50, SPO2 < 90 % will also be noted. At the end of surgery total dosage of Propofol/Dexmedetomidine and total amount of Sevoflurane consumed will be calculated. At the end of surgery neuromuscular blockade will be reversed. Total Duration of anesthesia will be noted. On emergence from anesthesia any episode of acute delirium will be recorded. Time from end of anesthesia to eye opening will be noted in both the groups. Neuropsychological Test consisting of Letter Digit Substitution Test, Trail Making Test Part A, Part B, Stroop Colour Word Test, Visual Verbal Learning Test will be performed 24 hours prior to surgery in the preanesthesia clinic and on postoperative day 3 and day 7.

Inclusion Criteria:

• Patient subjected to general anaesthesia for elective noncardiac surgical procedure with duration above 2 hours and postoperative stay for 3 days. Patient should be available for follow up on 7 th postoperative day.

Exclusion Criteria:

• Patients having severe psychosis on antidepressant medications, cerebral disease, pre-existing cognitive dysfunction with Mini Mental State Examination (MMSE) Score less than 23, history of drug abuse, significant visual and hearing impairment ,language difficulties and illiteracy.