The Effect of Esketamine on Postoperative Cognitive Function in Elderly Patients Undergoing Oral and Maxillofacial Surgery

Esketamine is a common anesthetic adjuvant. Previous studies have shown that it may have protective effects on the brain. This study aims to investigate whether esketamine can improve cognitive function recovery in elderly patients (aged 60 years and older) undergoing oral and maxillofacial surgery. Participants will be randomly assigned to receive either esketamine or a placebo (normal saline) during anesthesia. Neither the participants nor the researchers will know which treatment is given. Cognitive function will be assessed using standardized tests before surgery and at 1, 3, 7, and 15 days after surgery. Sleep quality, pain scores, emotional status, and adverse events will also be recorded. Blood samples will be collected to explore potential mechanisms. The study is expected to enroll approximately 98 participants at the Third Affiliated Hospital of Air Force Medical University in Xi'an, China. Participation will last about 16 days from the day before surgery to the final follow-up on day 15 after surgery.

Inclusion Criteria: Age ≥ 60 years, either sex; Scheduled for elective oral and maxillofacial surgery under general anesthesia (including oral and maxillofacial tumor surgery, orthognathic surgery, and maxillofacial trauma repair surgery); American Society of Anesthesiologists (ASA) physical status I-III; Expected duration of anesthesia ≥ 2 hours; Willing and able to provide written informed consent. Exclusion Criteria: Pre-existing behavioral disorders or psychiatric diseases (e.g., Alzheimer's disease, Parkinson's disease), or current use of antipsychotic medications (e.g., clozapine, risperidone, olanzapine, haloperidol, chlorpromazine); Pre-existing severe organ dysfunction including: severe cardiovascular disease (life-threatening arrhythmias, severe uncontrolled hypertension, coronary artery disease, heart failure), severe respiratory disease (respiratory failure, severe chronic obstructive pulmonary disease), severe hepatic insufficiency (Child-Pugh Class C), or severe renal insufficiency (glomerular filtration rate \< 30 mL/min or creatinine \> 2.5 mg/dL); Known contraindications to esketamine including: hypersensitivity to the active substance or any excipients; severe risk of elevated blood pressure or intracranial pressure; uncontrolled or untreated hypertension (resting systolic/diastolic blood pressure \> 180/100 mmHg); preeclampsia or eclampsia; untreated or inadequately treated hyperthyroidism; conditions requiring uterine relaxation (e.g., uterine rupture, umbilical cord prolapse); use as the sole anesthetic in patients with significant ischemic heart disease; Surgical approach that would interfere with postoperative MoCA assessment; Concurrent participation in another clinical trial; Pre-existing cognitive impairment or Mini-Mental State Examination (MMSE) score \< 24, unable to complete questionnaire-based assessments.