Cerebral Oxygen Consumption Response to Increased Oxygen Supply and Postoperative Delirium in Older Surgical Patients

Inclusion Criteria: * Patients undergoing elective laparoscopic surgery under general anesthesia * Age 65 years or older Exclusion Criteria: * Diagnosis of dementia or presence of delirium before surgery * Loss of capacity to provide informed consent * Moderate or severe cerebrovascular stenosis diagnosed before surgery * Moderate or severe obstructive or restrictive pulmonary dysfunction identified on preoperative pulmonary function testing * Requirement for supplemental oxygen therapy before surgery * History of neurological disorders (e.g., Parkinson's disease, stroke) or prior brain surgery * Severe hepatic dysfunction (AST or ALT \> 120 IU/L) * Severe renal dysfunction (estimated GFR \< 15 mL/min/1.73 m²) * Persistent severe hemodynamic instability (mean arterial pressure \< 60 mmHg) * Skin conditions preventing placement of the forehead fNIRS sensor * Combined surgical procedures performed concurrently * Planned postoperative admission to the intensive care unit