The goal of this observational study is to compare Incidence of postoperative delirium in Sarcopenic and non-sarcopenic elderly patients undergoing gastrointestinal surgery. The main question it aims to answer are:

• Effect of preoperative sarcopenia on postoperative delirium in elderly patients undergoing gastrointestinal surgery Participants will be evaluated preoperatively for sarcopenia and assessed for postoperative delirium, pain, etc.

Inclusion Criteria:

1. Age ≥ 65 years old, gender is not limited
2. Patients to undergo elective abdominal surgery (gastrointestinal tumor resection) under general anesthesia, with an expected operation duration of about 2h~4h
3. ASA Ⅰ-Ⅲ

Exclusion Criteria:

1. Relative contraindications to general anesthesia: Patients with severe heart and lung disease, severe infection, uncontrolled hypertension, diabetes, and severe diabetic complications
2. Abnormal renal and liver function: AST or ALT≥2.5×ULN, TBIL≥1.5×ULN, Serum creatinine concentration (SCC)≥1.5×ULN
3. People with a history of mental illness or long-term use of psychotropic drugs (dementia, schizophrenia), chronic analgesic drug use, alcoholism, and cognitive impairment
4. Any cardiovascular or cerebrovascular accidents occurred within 3 months, such as myocardial infarction, stroke, transient ischemic attack
5. Myasthenia gravis patients
6. Unable to cooperate to complete the test, the patient or family member rejected the participant

All patients who come to the Second Affiliated Hospital of Nanchang University for treatment