Intraoperative Infusion of Dexmedetomidine for Prevention of Postoperative Delirium in Elderly Patients

Exclusion Criteria

• •Operation time less than 2 hours.
• •Refusal to provide written informed consent.
• •Cognitive impairment before surgery(mini-mental state examination, MMSE ≤ 26 or Montreal Cognitive Assessment, MoCA≤22).
• •Allergic to the study drug.
• •Body mass index ≤18 or ≥ 30 kg/m2.
• •History of psychotropic drugs, anticholinergic drugs, antihistamine drug and dopaminergic drugs.
• •History of traumatic brain injury or neurosurgery.
• •Severe bradycardia (heart rate less than 40 beats per minute), sick sinus syndrome or second-to-third degree atrioventricular block.
• •Severe liver dysfunction (Child-Pugh grade C) or renal failure (requiring kidney replacement therapy).
• •The functional neurosurgery.