The goal of this observational study is to learn whether the brain's ability to use oxygen during surgery is associated with postoperative delirium in adults aged 65 years and older undergoing general anesthesia.
The main question it aims to answer is:
\- Does reduced cerebral oxygen consumption responsiveness during surgery increase the risk of postoperative delirium in older patients?
Participants who are undergoing elective laparoscopic surgery under general anesthesia as part of their routine medical care will have brain oxygen levels measured during surgery using a non-invasive forehead sensor, and will be assessed for delirium for up to three days after surgery.
Patients undergoing elective laparoscopic surgery under general anesthesia
Age 65 years or older
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
Participants will be recruited from patients scheduled for elective laparoscopic surgery at Seoul National University Bundang Hospital, a tertiary academic medical center in the Republic of Korea. Eligible patients will be identified during routine preoperative evaluation and approached for study participation prior to surgery.
Cohort
Prospective
Intraoperative Cerebral Oxygen Utilization Assessment
Other interventionCerebral oxygenation will be monitored intraoperatively using a non-invasive forehead sensor based on functional near-infrared spectroscopy technology. During general anesthesia, the fraction of inspired oxygen (FiO₂) may be temporarily adjusted within the standard clinical range used in routine anesthesia care to evaluate the brain's oxygen utilization response. No experimental oxygen levels or additional therapeutic interventions will be administered beyond standard clinical practice.
Incidence of Postoperative Delirium
Postoperative delirium diagnosed using 3D-CAM conducted in the post-anesthesia care unit and hospital ward. Delirium will be defined as at least one positive assessment during the first three postoperative days.
Intraoperative Cerebral Oxygen Utilization Response (ΔHbO-HbR)
Change in the difference between oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR), calculated as Δ(HbO-HbR), measured intraoperatively using functional near-infrared spectroscopy during variations in inspired oxygen concentration within the clinically applied range.
Predictive Performance of ΔHbO-HbR for Postoperative Delirium
Predictive accuracy of intraoperative Δ(HbO-HbR) for postoperative delirium assessed using receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (AUC) will be calculated to quantify discrimination.
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