Delirium is a common postoperative complication in the elderly, often caused by multiple factors. It is defined as an acute neuropsychiatric disorder characterized by fluctuating disturbances in attention, awareness, and cognition. Postoperative delirium occurs in 17-61% of the major surgical procedures. It may be associated with cognitive decline, decreased functional independence, increased risk of dementia, caregiver burden, health care costs, morbidity, and mortality. Therefore, delirium is a possibly disastrous condition and is both a huge burden on a patient's health and on the health care system in general.

Over the last few decades, numerous risk factors for delirium have been identified, emphasizing the importance of delirium prevention in patients undergoing surgery. It has already been identified as a state that may be associated with serious complications such as prolonged ICU and hospital stays, decreased quality of life, and increased mortality ). Previous studies on delirium pointed out old age and other factors as important predisposing factors. on the health care system in general. Extensive research on reducing the incidence of delirium has been conducted using both pharmacological and non-pharmacological preventive measures in the acute setting. As evidence recommending or opposing specific drugs for the prevention of postoperative delirium remains insufficient and the international guidelines can only recommend perioperative pharmacologic adjustments ("American Geriatrics Society Abstracted Clinical Practice Guideline for Postoperative Delirium in Older Adults," 2015) . Consequently, the challenge of developing reliable hospital algorithms for delirium prevention and treatment remains unresolved. Furthermore, there is a link between postoperative delirium and two biomarkers, cortisol and C- Reactive Protein (CRP), which have previously been linked to delirium but whose significance is unknown.

Inclusion Criteria:

• 1- Patients aged ≥ 65 years. 2- Scheduled for visceral, orthopedic, vascular, obstetric, urology, or plastic surgery.

Exclusion Criteria:

• 1- Delirium upon hospital admission or development of delirium prior to surgery stated by family members.

  2- Mini-Mental State Examination (MMSE) score < 24 points 3- Delirium Observation Scale (DOS) ≥4 points 4- preoperative neurological diseases affecting cognitive function (such as vascular dementia) 5- High risk for postoperative treatment in the intensive care unit (ICU) 6- Known to have dexmedetomidine and or ketamine intolerance. 7- Lack of cooperation or communication. 8- Parkinson's disease, parkinsonism, intake of dopaminergic drugs (levodopa, dopamine agonists) 9- Epilepsy. 10- Patients on steroid therapy 11- severe liver and renal insufficiency