This prospective observational cohort study aims to investigate whether early postoperative changes in heart rate variability (HRV) relative to baseline are associated with the development of postoperative delirium (POD) in older patients undergoing elective major abdominal surgery under general anesthesia. Patients aged 65-85 years will be enrolled. Resting HRV will be measured at 10:00 AM on the day of surgery before anesthesia induction and at the same time point on the first postoperative day using a validated heart rate monitoring device. HRV parameters will be derived from standardized 5-minute recordings. Changes in HRV parameters from baseline will be calculated, and their associations with POD occurrence will be evaluated. Postoperative delirium will be assessed daily from 24 hours after surgery to postoperative day 7, using the 3-Minute Diagnostic Interview for Confusion Assessment Method (3D-CAM). The study will also explore the potential utility of HRV-derived markers for early POD risk stratification. Approximately 500 participants will be enrolled.
Patients admitted to Jiangsu Provincial People's Hospital who are scheduled to undergo elective major abdominal surgery under general anesthesia.
Older patients aged 65 to 85 years.
Expected postoperative hospital stay of ≥7 days.
Body mass index (BMI) between 18.5 and 28.0 kg/m².
Patients with ASA physical status classification ≥IV or patients with end-stage cancer.
Patients with implanted cardiac pacemakers, implantable cardioverter-defibrillators, or other electronic devices that may interfere with ECG signal acquisition.
Patients with severe or unstable cardiovascular diseases, including but not limited to acute coronary syndrome, symptomatic bradycardia, sick sinus syndrome, second-degree or higher atrioventricular block, atrial fibrillation, atrial flutter, frequent premature beats, or other arrhythmias that may affect heart rate variability analysis.
Patients with diseases affecting autonomic nervous system function, including confirmed primary or secondary autonomic dysfunction, such as Parkinson's disease, multiple system atrophy, severe diabetic autonomic neuropathy, severe peripheral neuropathy, poorly controlled hyperthyroidism or hypothyroidism, and systemic amyloidosis.
Older patients aged 65 to 85 years undergoing elective major abdominal surgery under general anesthesia will be prospectively enrolled. Perioperative heart rate variability will be assessed before surgery and within 24 hours after surgery, and participants will be followed for the occurrence of postoperative delirium during the first 7 postoperative days.
Cohort
Prospective
Perioperative Heart Rate Variability Changes
Other interventionHeart rate variability will be measured using standardized 5-minute recordings at predefined time points: 10:00 AM on the day of surgery before surgery and 10:00 AM on postoperative day 1 (within 24 hours after surgery). Perioperative changes in heart rate variability will be evaluated as an observational exposure to investigate their association with postoperative delirium in older patients undergoing elective major abdominal surgery under general anesthesia.
Occurrence of postoperative delirium within 7 days after surgery
Postoperative delirium will be assessed daily from postoperative day 1 to postoperative day 7 using the Chinese version of the 3-Minute Diagnostic Interview for CAM-defined Delirium (3D-CAM). Delirium diagnosis will be based on the Confusion Assessment Method (CAM) algorithm.
Severity of postoperative delirium
The severity of postoperative delirium will be assessed using the Delirium Rating Scale-Revised-98 (DRS-R-98) among patients who develop postoperative delirium. The DRS-R-98 scores range from 0 to 46, with higher scores indicating greater delirium severity (worse outcome).
Duration of postoperative delirium
The duration of postoperative delirium episodes will be recorded from the first diagnosis of delirium until resolution during the postoperative assessment period.
Change in cognitive function after surgery
Cognitive function will be assessed using the Montreal Cognitive Assessment (MoCA). Scores range from 0 to 30, with higher scores indicating better cognitive function (better outcome).
Quality of recovery after surgery
Quality of recovery will be assessed using the 15-item Quality of Recovery Questionnaire (QoR-15). Scores range from 0 to 150, with higher scores indicating better quality of recovery (better outcome).
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