Detection and Classification of Levels of Consciousness Using Parietal EEG-fNIRS During Anesthesia

April 3, 2024 updated by: Catalina Saini Ferrón, Pontificia Universidad Catolica de Chile
The current evaluations of the levels of consciousness during anesthesia have limited precision. This can produce negative clinical consequences such as intraoperative awareness or neurological damage due to under- or over-infusion of anesthesia, respectively. The study's objective is to determine and classify biomarkers of electrical and hemodynamical brain activity associated with the levels of consciousness between wakefulness and anesthesia. For this purpose, a parietal electroencephalography (EEG) and a functional near-infrared spectroscopy (fNIRS) measurement paradigm will be used, as well as machine-learning. Volunteering patients (n = 25), who will be subject to an endoscopy procedure, will be measured during the infusion of anesthesia with propofol. EEG and fNIRS parameters will then be related to the Modified Ramsay clinical scale of consciousness.

Study Overview

Status

Completed

Conditions

Detailed Description

Devices for data acquisition The brain electrical signals will be measured with four electrodes and a Cyton OpenBCI board with a sampling frequency of 250 Hz. The brain hemodynamical signals will be measured with a NIRSport with 16 optodes and a sampling frequency of 15.525 Hz and a wavelength of 760 nm. The electrodes and optodes will be positioned in the parietal zone, following the recommended 10-5 system for the multimodal EEG-fNIRS paradigm. The software Lab Streaming Layer will be used to synchronize the EEG and fNIRS data.

Data acquisition Patients will be summoned 30 minutes before their clinical appointment to put, adjust and calibrate the EEG and fNIRS systems. A 5-minute baseline measurement will be performed before the endoscopy procedure, with eyes closed. Afterward, patients will be anesthetized with a constant infusion rate of 20 mg/kg/h-1 of intravenous propofol until loss of consciousness, within 20 minutes. During infusion, the Modified Ramsay Scale will be used by the anesthetist in charge to measure the levels of consciousness, assessed by the patient's response to verbal or painful stimuli. The level of consciousness will be evaluated every two minutes until complete loss of consciousness, which is assumed after the loss of defensive or purposeful response to a second standard tetanic stimulation. After this, the endoscopy procedure will continue normally following standard clinical protocols. Before leaving, patients will be asked to answer the BRICE survey, used to evaluate the patient's experience during surgery or similar procedures. Patients will be measured throughout the whole endoscopy procedure. Any additional considerations will be managed in a case-by-case manner by the medical staff in charge.

Justification of the chosen sample size The sample size (n = 25) was determined by the Cohen Test, with a statistical power of 0.8 and an alfa power of 0.05, to determine significant intraspecific subject differences when comparing wakefulness, deep sedation, and intermediate levels of consciousness.

EEG data analysis The delta (0.1-3 Hz), theta (4-7 Hz), lower-alpha (8-12 Hz), upper-alpha (12-15 Hz), and beta/gamma (15-40 Hz) power bands will be used as features for the decoding model. The features will be calculated using a moving window of one minute. The levels of consciousness identified using the Modified Ramsay Scale will be paired with the corresponding window. The software Homer 2012: MNE in Python will be used for these analyses.

fNIRS data analysis The temporal reference of the oxygenated (HbO2) and deoxygenated (HHb) hemoglobin will be obtained from the optical signals, using the modified Beer-Lambert law. The regions of interest (ROIs) will be obtained in relation to regional local average activity. The average, maximal, and slope of the signal of each ROI will be obtained. Vector-phase analyses will also be implemented, with one-minute windows. The software Homer 2021: MNE in Python will be used for these analyses.

Classification using machine-learning For each one-minute window, the EEG and fNIRS features will be given to a Support Vector Machine (SVM) classifier using a basal radius. Each window will be attached to the level of consciousness according to the Modified Ramsay Scale. Three models will be tested: only EEG, only fNIRS, and fNIRS + EEG. Each model will try to decode the patient's level of consciousness using the aforementioned scale.

Study Type

Observational

Enrollment (Actual)

13

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, 8320000
        • Centro de Especialidades Médicas UC

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

20 years to 40 years (Adult)

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Relatively healthy volunteering patients, within 20 to 40 years of age, who will undergo an endoscopy procedure and meet all the eligibility criteria.

Description

Inclusion Criteria:

  • ASA I or II
  • Patients who will undergo an endoscopy procedure

Exclusion Criteria:

  • Alcohol or drug consumption within 48 hours
  • Known or suspected pregnancy
  • Any diagnosed psychiatric condition
  • Any diagnosed neurological condition or implant
  • Any diagnosed chronic disease

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Brain electrophysiological activity by electroencephalography wavelength band powers
Time Frame: During the whole endoscopy and recovery (1 - 2 hours)
The delta (0.1-3 Hz), theta (4-7 Hz), lower-alpha (8-12 Hz), upper-alpha (12-15 Hz), and beta/gamma (15-40 Hz) electroencephalography wavelength band powers will be used as features for the decoding model.
During the whole endoscopy and recovery (1 - 2 hours)
Temporal brain oxygenation by near-infrared light spectroscopy wavelengths
Time Frame: During the whole endoscopy and recovery (1 - 2 hours)
The temporal brain area of the oxygenated (HbO2) and deoxygenated (HHb) hemoglobin will be obtained from the optical signals, using the modified Beer-Lambert law.
During the whole endoscopy and recovery (1 - 2 hours)
Levels of Consciousness with the Modified Ramsay Sedation Scale
Time Frame: 20 minutes
During infusion, the Modified Ramsay Scale will be used by the anesthetist in charge to measure the patient's level of consciousness. This scale has a total of eight levels, each of which indicates an increasing level of unconsciousness, assessed qualitatively by the patient's response to verbal or painful stimuli. The level of consciousness will be evaluated every two minutes until complete loss of consciousness, which is assumed after the loss of defensive or purposeful response to a second standard tetanic stimulation.
20 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
BRICE survey responses
Time Frame: 10 minutes
Before leaving, patients will be asked to answer the BRICE survey, used to evaluate the patient's experience during surgery or similar procedures (Table 6. in Kotsovolis & Komninos, 2009).
10 minutes

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: Catalina A Saini, 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

Helpful Links

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 14, 2022

Primary Completion (Actual)

March 1, 2023

Study Completion (Actual)

March 1, 2023

Study Registration Dates

First Submitted

October 10, 2021

First Submitted That Met QC Criteria

October 27, 2021

First Posted (Actual)

November 8, 2021

Study Record Updates

Last Update Posted (Actual)

April 4, 2024

Last Update Submitted That Met QC Criteria

April 3, 2024

Last Verified

April 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 210716001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The Department of Anesthesiology and the Institute of Biological and Medical Engineering (IIBM) of the Pontificia Universidad Católica de Chile, will take the necessary measurements to protect the access to your clinical information and sensible data from unauthorized people. All the obtained information will be kept confidential. The name, ID, or any other identifiable information, will be anonymized in a database. This information will be stored for five years under the responsibility of the corresponding researchers. The collected data will be published to be used in other studies related to anesthesia and consciousness. All published data will be completely anonymized. It is possible that the obtained results are presented in journals and medical or scientific conferences. However, the name and identifiable data will not be known.

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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