Electroencephalogram Characteristics of Surgical Anesthetized Patients and Postoperative Dilirium

January 8, 2026 updated by: Gan Shuyuan, First Affiliated Hospital of Zhejiang University

Electroencephalogram Characteristics of Surgical Anesthetized Patients and Their Correlation With Postoperative Delirium

Objective: To construct a perioperative EEG database for elderly patients under general anesthesia and to explore the relationship between their EEG spectrum characteristics and the occurrence and severity of postoperative delirium. Content: This study aims to investigate elderly patients undergoing elective orthopedic surgery under general anesthesia with endotracheal intubation, analyze the changes in the perioperative EEG spectrum and its correlation with the occurrence of postoperative delirium, and explore the relationship between perioperative EEG changes and the occurrence of postoperative delirium. Methods: Patients aged 60 years or older who were scheduled to undergo orthopedic joint replacement or spinal surgery and had a hospital stay of more than 2 days were selected. All patients underwent MMSE and 3D-CAM assessment before surgery. Before anesthesia induction, anesthesia depth monitoring electrodes were placed on the patient's occipital or frontal temporal region, and EEGs were collected in awake and quiet states, under general anesthesia, and during anesthesia recovery. In the PACU, the score was calculated based on the CAM-ICU scale. The patients were assessed with the 3D-CAM scale for awakening once a day at 15:00-20:00 the day before surgery, and twice a day at 9:00-11:00 and 15:00-20:00 during 1-5 days after surgery, or at any time when obvious delirium symptoms appeared, unless discharged from the hospital or taking sedatives (RASS<-3). Ten minutes after the assessment, the occipital EEG was monitored when the patient was conscious and quiet, or when obvious delirium appeared. According to the test results of the 3D-CAM scale, it was determined whether the patient had postoperative delirium, and the patients were divided into the delirium group and the non-delirium group. The EEG characteristics of the two groups of patients were analyzed before, during, and after surgery. Research significance: The results of this study can provide objective indicators and theoretical basis for monitoring and diagnosing the occurrence and development of POD, which can help clinicians to identify patients with increased risk of delirium at an early stage, adjust the plan in time, and change the triggering risk factors of POD.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

Detailed Description

Preoperative cognitive and delirium assessment:

MMSE scale assesses the patient's preoperative cognitive function status: the total score is 30 points, the higher the score, the better the cognitive function. Considering the impact of education level on MMSE assessment, combined with my country's actual situation and previous studies, we set the assessment criteria for illiterate or most primary and junior high school education levels to ≤17, ≤20, and ≤24, respectively. Individuals below the corresponding standards are considered to have cognitive impairment before surgery.

Preoperative 3D-CAM baseline value for delirium assessment: patients were assessed for delirium using the 3-minute rapid mental confusion assessment method (3D-CAM) between 15:00 and 20:00 the day before surgery.

Postoperative delirium assessment:

During the postoperative PACU period, the score was calculated based on the CAM-ICU scale; 1-5 days after surgery, patients underwent 3D-CAM assessment twice a day at 9:00-11:00 and 15:00-20:00, or at any time when obvious delirium symptoms appeared, unless discharged or taking sedatives (RASS<-3).

Study Type

Observational

Enrollment (Estimated)

375

Contacts and Locations

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

Study Locations

  • China
    • Zhejiang
      • Hangzhou, Zhejiang, China, 310003
        • The First Affiliated Hospital, Zhejiang University, School of Medicine

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Elderly patients undergoing elective orthopedic joint replacement or spinal surgery

Description

Inclusion Criteria:

Patients aged ≥ 60 years, scheduled for orthopedic joint replacement or spinal surgery, ASA grade I-III, expected surgery time ≥ 2 hours, and able to provide written informed consent.

Exclusion Criteria:

  1. Patients with central nervous system diseases or mental disorders;
  2. patients with severe systemic diseases such as cardiopulmonary, liver and kidney dysfunction, coagulation dysfunction, etc.;
  3. patients who frequently use psychotropic drugs, opioids or corticosteroids;
  4. patients with a history of intraoperative awareness;
  5. patients who are unable to complete preoperative delirium screening due to severe blindness, deafness, illiteracy or Mandarin speaking;
  6. patients who are expected to undergo a second operation within 7 days.

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
Delirium group
If the patient develops delirium after surgery, he/she is in the delirium group
Diagnostic test: Delirium test scale：3D-CAM
The 3D-CAM is a 3-minute delirium assessment that is also based upon the CAM algorithm and has four features: (1) altered mental status/fluctuating course, (2) inattention, (3) altered level of consciousness, and (4) disorganized thinking.
Non delirium group
If the patient does not experience delirium after surgery, it is considered as the non-delirium group
Diagnostic test: Delirium test scale：3D-CAM
The 3D-CAM is a 3-minute delirium assessment that is also based upon the CAM algorithm and has four features: (1) altered mental status/fluctuating course, (2) inattention, (3) altered level of consciousness, and (4) disorganized thinking.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation between perioperative EEG spectral changes and postoperative delirium
Time Frame: 2 years
Characteristic changes of EEG spectral changes in patients with POD before, during, and after surgery
2 years
Incidence of POD
Time Frame: 1 years
The proportion of POD occurrence
1 years

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of POD
Time Frame: 1 years
The proportion of postoperative POD occurrence
1 years

Collaborators and Investigators

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

Sponsor

First Affiliated Hospital of Zhejiang 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 (Actual)

May 13, 2024

Primary Completion (Estimated)

September 30, 2026

Study Completion (Estimated)

April 15, 2027

Study Registration Dates

First Submitted

April 29, 2024

First Submitted That Met QC Criteria

April 29, 2024

First Posted (Actual)

May 1, 2024

Study Record Updates

Last Update Posted (Estimated)

January 12, 2026

Last Update Submitted That Met QC Criteria

January 8, 2026

Last Verified

August 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IIT20240135B-R1

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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