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

Association Between Cerebral Oxygen Consumption Responsiveness to Increased Oxygen Supply and Postoperative Delirium: A Prospective Observational Study Using Functional Near-Infrared Spectroscopy

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.

Study Overview

• Status: Recruiting
• Conditions: Cerebral Oxygenation; Delirium - Postoperative
• Intervention / Treatment: Other: Intraoperative Cerebral Oxygen Utilization Assessment

• Study Type: Observational
• Enrollment (Estimated): 80

Contacts and Locations

• Study Contact: Name: Soowon Lee, MD, PhD; Phone Number: +82-31-787-7499; Email: soowonlee@snubh.org

Study Locations

• South Korea
  • Gyeonggi-do
    • Seongnam-si, Gyeonggi-do, South Korea, 13620
      • Recruiting
      • Seoul National University Bundang Hospital
      • Contact: Soowon Lee, MD, PhD; Phone Number: +82-31-787-7499; Email: soowonlee@snubh.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: N/A

• Sampling Method: Probability Sample

Study Population

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.

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Older patients undergoing elective laparoscopic surgery; Adults aged 65 years and older undergoing elective laparoscopic surgery under general anesthesia will be prospectively observed. During surgery, cerebral oxygen levels will be measured using a non-invasive forehead sensor to assess the brain's oxygen utilization response within the range of routine anesthesia care. Participants will be followed for up to three days after surgery to evaluate the occurrence of postoperative delirium.

Other: Intraoperative Cerebral Oxygen Utilization Assessment; Cerebral 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Up to 3 days after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	During surgery

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Up to 3 days after surgery

Collaborators and Investigators

• Sponsor: Seoul National University Bundang Hospital

Study record dates

Study Major Dates

• Study Start (Actual): March 11, 2026
• Primary Completion (Estimated): March 1, 2028
• Study Completion (Estimated): May 1, 2028

Study Registration Dates

• First Submitted: March 3, 2026
• First Submitted That Met QC Criteria: March 8, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): April 2, 2026
• Last Update Submitted That Met QC Criteria: March 29, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Mental Disorders; Postoperative Complications; Pathologic Processes; Confusion; Neurobehavioral Manifestations; Neurocognitive Disorders; Delirium; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Emergence Delirium
• Other Study ID Numbers: B-2602-1024-002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES