Effects of different anesthesia regimens on cerebral oxygenation and early postoperative cognitive function in elderly NFBF patients

INTERVENTION: Group P:Intraoperative anesthesia was maintained with total intravenous anesthesia via continuous propofol infusion throughout the procedure.;Group S:Intraoperative anesthesia was maintained with sevoflurane inhalation anesthesia throughout the procedure.; CONDITION: Postoperative Cognitive Dysfunction PRIMARY OUTCOME: Intraoperative absolute change value of rSO2;Mimi‐mentalstate Examination Score; INCLUSION CRITERIA: 1. Patients aged >= 65 years, ASA classification II‐III, scheduled for laparoscopic gastrointestinal surgery; 2. Preoperative Mini‐Mental State Examination score not less than 23; 3. History of cerebral hemorrhage, cerebral infarction, TIA, cerebrovascular stenosis, Parkinson's disease, chronic headaches or dizziness, but no episodes in the past three months and no corresponding clinical symptoms.