Heart Rate Variability Changes and Postoperative Delirium After Major Abdominal Surgery (HRVPOD)

August 28, 2026 updated by: Wu Junbei, The First Affiliated Hospital with Nanjing Medical University

Predictive Value of Early Postoperative Heart Rate Variability Changes From Baseline for Postoperative Delirium in Older Adults Undergoing Major Abdominal Surgery: A Prospective Cohort Study

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.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Postoperative delirium (POD) is a common neurocognitive complication following major surgery in older adults and is associated with increased morbidity, prolonged hospitalization, and adverse clinical outcomes. However, objective and easily obtainable biomarkers for early identification of patients at high risk of POD remain limited.

Heart rate variability (HRV) reflects autonomic nervous system regulation and may provide a non-invasive marker of physiological stress and impaired autonomic adaptability. Major abdominal surgery induces substantial systemic stress responses, including inflammation, neuroendocrine activation, and autonomic disturbances. Whether early postoperative alterations in HRV are associated with subsequent POD development remains unclear.

This is a single-center, prospective observational cohort study. Patients aged 65-85 years undergoing elective major abdominal surgery under general anesthesia will be consecutively enrolled. Baseline demographic characteristics, comorbidities, frailty status, cognitive function, and perioperative clinical variables will be collected.

Resting HRV will be measured at 10:00 AM on the day of surgery before anesthesia induction and again at the same time point on the first postoperative day using a validated heart rate monitoring device. HRV analysis will be performed based on standardized 5-minute recordings in accordance with established recommendations for short-term HRV assessment. Time-domain, frequency-domain, and nonlinear HRV parameters will be calculated.

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). Additional clinical outcomes include delirium severity, delirium duration, postoperative cognitive function, quality of recovery, postoperative nausea and vomiting, and length of hospital stay.

The primary objective is to evaluate the association between early postoperative HRV changes and the occurrence of POD after adjustment for clinically relevant confounding factors, including age, baseline cognitive function, frailty status, surgical duration, and baseline HRV. Secondary analyses will explore the relationship between representative HRV markers and postoperative clinical outcomes and assess their potential utility for early POD risk stratification.

Study Type

Observational

Enrollment (Estimated)

500

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • China
    • Jiangsu
      • Nanjing, Jiangsu, China, 210029
        • The First Affiliated Hospital with Nanjing Medical University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

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.

Description

Inclusion Criteria

  1. Patients admitted to Jiangsu Provincial People's Hospital who are scheduled to undergo elective major abdominal surgery under general anesthesia.
  2. Older patients aged 65 to 85 years.
  3. Expected postoperative hospital stay of ≥7 days.
  4. Body mass index (BMI) between 18.5 and 28.0 kg/m².
  5. American Society of Anesthesiologists (ASA) physical status classification I-III.
  6. Patients who are conscious, mentally competent, and able to cooperate with heart rate variability (HRV) measurements, questionnaire assessments, and follow-up evaluations.
  7. Patients who voluntarily participate in the study and provide written informed consent.

Exclusion Criteria

  1. Patients with ASA physical status classification ≥IV or patients with end-stage cancer.
  2. Patients with implanted cardiac pacemakers, implantable cardioverter-defibrillators, or other electronic devices that may interfere with ECG signal acquisition.
  3. 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.
  4. 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.
  5. Patients with a history of organic central nervous system diseases or psychiatric disorders, including major traumatic brain injury, stroke (ischemic or hemorrhagic), intracranial mass lesions, epilepsy, schizophrenia, bipolar disorder, major depressive disorder, or other severe psychiatric disorders.
  6. Patients with severe baseline cognitive impairment or inability to complete cognitive assessments, including any of the following: (1) preoperative baseline Montreal Cognitive Assessment (MoCA) score <14 points; (2) previously diagnosed dementia, preoperative delirium, coma, or other severe disturbances of consciousness; or (3) inability to complete standardized cognitive assessments due to severe visual impairment, hearing impairment, language barriers, or other causes.
  7. Patients unable to undergo HRV measurement within 24 hours after surgery, including those with severe perioperative complications, emergency reoperation, extremely unstable vital signs, or requiring continuous deep sedation after surgery.
  8. Patients who have taken anticholinergic medications, beta-blockers, antiarrhythmic drugs, or other medications that may significantly affect autonomic function within 1 month before study enrollment.
  9. Patients who are currently participating in any other clinical trial.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Elderly Patients Undergoing Elective Major Abdominal Surgery
Elderly patients undergoing elective major abdominal surgery under general anesthesia will be prospectively enrolled and followed for postoperative delirium.
Other: Perioperative Heart Rate Variability Changes
Heart 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Occurrence of postoperative delirium within 7 days after surgery
Time Frame: Postoperative day 1 to postoperative day 7 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.
Postoperative day 1 to postoperative day 7 after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Duration of postoperative delirium
Time Frame: Postoperative day 1 to postoperative day 7 after surgery
The duration of postoperative delirium episodes will be recorded from the first diagnosis of delirium until resolution during the postoperative assessment period.
Postoperative day 1 to postoperative day 7 after surgery
Severity of postoperative delirium
Time Frame: Postoperative day 1 to postoperative day 7 after surgery
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).
Postoperative day 1 to postoperative day 7 after surgery
Change in cognitive function after surgery
Time Frame: Postoperative day 7
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).
Postoperative day 7
Quality of recovery after surgery
Time Frame: Postoperative day 7
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).
Postoperative day 7

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

The First Affiliated Hospital with Nanjing Medical University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 1, 2026

Primary Completion (Estimated)

April 30, 2027

Study Completion (Estimated)

May 15, 2027

Study Registration Dates

First Submitted

August 18, 2026

First Submitted That Met QC Criteria

August 18, 2026

First Posted (Actual)

August 24, 2026

Study Record Updates

Last Update Posted (Actual)

August 31, 2026

Last Update Submitted That Met QC Criteria

August 28, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026-SR-0106

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared with other researchers. The study involves detailed perioperative clinical information, heart rate variability data, and cognitive and delirium assessments collected from older surgical patients. Due to privacy protection, ethical considerations, and the absence of a predefined data-sharing plan in the informed consent process, individual participant data will not be made publicly available.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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