Association Between Burst Suppression During Anesthetic Induction With Postoperative Delirium in Cardiac Surgery

May 27, 2025 updated by: Pontificia Universidad Catolica de Chile

Study of the Association Between Burst Suppression During Anesthetic Induction With Propofol in Cardiac Surgery in Patients Over 65 Years of Age With Postoperative Delirium

The population over 65 years of age will be increasingly exposed to surgical procedures that require general anesthesia. Postoperative delirium is one of the main causes of preventable postoperative morbidity in the elderly population and is a frequent event after cardiac surgery with extracorporeal circulation. The excess administration of anesthetics that potentiate the Gamma Aminobutyric A receptor, such as propofol, are related to an intraoperative electroencephalographic pattern called burst suppression that has been associated with postoperative delirium. It is unknown whether this pattern is secondary to a relative overdose of anesthetics or rather corresponds to a characteristic of a vulnerable brain that is suppressed at doses at which other patients are not. Our objective will be to determine whether burst suppression in people over 65 years of age during a standardized anesthetic induction with propofol for cardiac surgery with extracorporeal circulation is associated with postoperative delirium compared to older people who do not present it.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Perioperative neurocognitive disorders, including postoperative delirium (POD), are the leading cause of preventable postoperative morbidity in the elderly population. POD is an acute brain dysfunction characterized by changes in attention and cognition usually within of the first week after surgery and anesthesia. Its appearance triggers a series of events that often end in loss of independence, increased morbidity and mortality and increased health costs. It has been associated with the development of long-term cognitive impairment, including persistent dementia. Its nature is multifactorial and its pathophysiology is not yet fully elucidated.

Over administration of anesthetics that potentiate the Gamma Amino Butyric A (GABAA) receptor, such as barbiturates or propofol, is related to an intraoperative electroencephalographic (EEG) pattern called burst suppression that has been associated with POD. It is a common event after cardiac surgery with an incidence ranging from 15% to 50%. Given its adverse impact on functioning and quality of life, delirium has enormous social implications for the individual, family, community, and health care systems.

Burst suppression is a pattern observed in the EEG characterized by quasi-periodic alternations between isoelectricity (flat EEG) and brief bursts of electrical activity such as spikes, sharp waves, or slow waves. It reflects a brain state of relative cortical inactivity that is not observed during normal waking states or sleeping behaviors. This pattern can be observed associated with coma due to diffuse anoxic damage, induced hypothermia and Ohtahara syndrome epilepsy. In addition, the administration of high-dose anesthetics that potentiate the GABAA receptor produce burst suppression followed by isoelectricity. Burst suppression during maintenance of general anesthesia with anesthetics that enhance the GABAA receptor has previously been associated with POD. When propofol is administered as a bolus during anesthetic induction, older patients, can suffer burst suppression in seconds. However, it is unknown whether this pattern is secondary to a relative overdose of anesthetics or rather corresponds to a characteristic of the vulnerable brain that is suppressed at doses to which other patients do not present this pattern. At present, it is not known whether burst suppression is a modifiable risk factor for POD or an epiphenomenon or marker of other factors that cause POD. A randomized controlled clinical trial studied an EEG-guided anesthetic protocol that reduced the administration of anesthetic, diminished the incidence of burts suppression during the intraoperative period, but not the incidence of POD. Therefore, the association between bursts suppression induced by anesthetics and POD appears not to be causal.

Study Type

Observational

Enrollment (Actual)

78

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

  • Chile
    • Región Metropolitana
      • Santiago, Región Metropolitana, Chile, 8330024
        • Hospital Clínico Pontificia Universidad Católica de Chile

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

65 years to 100 years (Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Patients over 65 years of age undergoing cardiac surgery with cardiopulmonary bypass.

Description

Inclusion Criteria:

  • Patients ≥ 65 years of age
  • Undergoing elective cardiac surgery requiring extracorporeal circulation (coronary artery bypass, univalvular replacement, bivalvular and coronary artery bypass plus univalvular replacement)
  • American Society of Anesthesiologists Physical Status II-III.

Exclusion Criteria:

  • Body Mass Index > 35 and <18 Kg / m2
  • Severe ventricular dysfunction (EF < 30% or severe dysfunction measured in ventriculography)
  • Emergency surgery
  • Chronic use of alcohol or drug abuse
  • History of Stroke
  • Neurological diseases
  • Endocarditis
  • Positive screening for preoperative delirium.

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
Burst Suppression
Patients who present burst suppression after standardized propofol administration during anesthetic induction
Drug: Standardized Propofol Administration
Intravenous bolus propofol administration of 0.5 mg/Kg dose, plus 0.5 mg/Kg extra if necessary
No Burst Suppression
Patients who did not present burst suppression after standardized propofol administration during anesthetic induction
Drug: Standardized Propofol Administration
Intravenous bolus propofol administration of 0.5 mg/Kg dose, plus 0.5 mg/Kg extra if necessary

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Delirium
Time Frame: Up to 72 hours after surgery (3 postoperative days), CAM or CAM-ICU assessed twice daily (AM/PM)
Positive Confusion Assessment Method (CAM), Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), or structured chart review
Up to 72 hours after surgery (3 postoperative days), CAM or CAM-ICU assessed twice daily (AM/PM)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Burst suppression during anesthesia induction
Time Frame: 20 minutes after standardized propofol administration
Burst suppression incidence after standardized propofol induction in patients ≥ 65 years scheduled for cardiac surgery with cardiopulmonary bypass
20 minutes after standardized propofol administration
Burst suppression during cardiopulmonary bypass
Time Frame: Through Cardiopulmonary bypass time defined as time between connection to pump to disconnection, an average of 120 minutes
Burst suppression incidence during cardiopulmonary bypass in patients ≥ 65 years scheduled for cardiac surgery with cardiopulmonary bypass
Through Cardiopulmonary bypass time defined as time between connection to pump to disconnection, an average of 120 minutes
Preoperative Cognitive Status
Time Frame: Preoperative anesthetic evaluation
Preoperative cognitive assessment using MiniCog, minimum value: 0 - maximum value:5 , higher scores meaning better outcomes. If MiniCog ≤ 2, MoCA (Montreal Cognitive Assessment) exam will be performed.
Preoperative anesthetic evaluation
Preoperative Frailty
Time Frame: Preoperative anesthetic evaluation
Preoperative frailty evaluation using Clinical Frailty Scale (CFS), minimum value: 1(Very Fit) - maximum value: 9 (Terminally Ill), higher scores meaning worse outcomes
Preoperative anesthetic evaluation
Electroencephalogram (EEG) Alpha Power/Total Power
Time Frame: Stable anesthetic period before cardiopulmonary bypass and 20 minutes after propofol induction
Electroencephalogram power between 8 to 12 Hz (Alpha) and 0.1 to 35 Hz (Total)
Stable anesthetic period before cardiopulmonary bypass and 20 minutes after propofol induction
CRP (C Reactive Protein)
Time Frame: Blood sample collection during arterial line insertion, before anesthetic induction
Serum C Reactive Protein
Blood sample collection during arterial line insertion, before anesthetic induction

Collaborators and Investigators

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

Sponsor

Pontificia Universidad Catolica de Chile

Investigators

  • Principal Investigator: Juan C Pedemonte, MD, Pontificia Universidad Catolica de Chile

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)

March 1, 2021

Primary Completion (Actual)

February 28, 2024

Study Completion (Actual)

September 1, 2024

Study Registration Dates

First Submitted

January 11, 2021

First Submitted That Met QC Criteria

January 13, 2021

First Posted (Actual)

January 19, 2021

Study Record Updates

Last Update Posted (Actual)

May 31, 2025

Last Update Submitted That Met QC Criteria

May 27, 2025

Last Verified

November 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 200923005

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

All data will be collected and saved in digital forms. Data may be shared with other researchers with previous authorization from the PI.

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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