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

Anesthesia Clinical Trial

Official title:

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

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT05112042
• Other study ID #: 210716001
• Status: Completed
• Start date: May 14, 2022
• Est. completion date: March 1, 2023

Study information

• Verified date: April 2024
• Source: Pontificia Universidad Catolica de Chile
• Contact: n/a
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 13
• Est. completion date: March 1, 2023
• Est. primary completion date: March 1, 2023
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 20 Years to 40 Years

Eligibility

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

Related Conditions & MeSH terms

• Anesthesia
• Consciousness, Loss of
• Unconsciousness

Locations

Country	Name	City	State
Chile	Centro de Especialidades Médicas UC	Santiago	Región Metropolitana

Sponsors (1)

Lead Sponsor	Collaborator
Pontificia Universidad Catolica de Chile

Country where clinical trial is conducted

Chile, 

References & Publications (15)

Aru J, Suzuki M, Larkum ME. Cellular Mechanisms of Conscious Processing. Trends Cogn Sci. 2020 Oct;24(10):814-825. doi: 10.1016/j.tics.2020.07.006. Epub 2020 Aug 24. Erratum In: Trends Cogn Sci. 2021 Dec;25(12):1096. — View Citation

Campbell JM, Huang Z, Zhang J, Wu X, Qin P, Northoff G, Mashour GA, Hudetz AG. Pharmacologically informed machine learning approach for identifying pathological states of unconsciousness via resting-state fMRI. Neuroimage. 2020 Feb 1;206:116316. doi: 10.1016/j.neuroimage.2019.116316. Epub 2019 Oct 29. — View Citation

Davidson AJ. Anesthesia and neurotoxicity to the developing brain: the clinical relevance. Paediatr Anaesth. 2011 Jul;21(7):716-21. doi: 10.1111/j.1460-9592.2010.03506.x. Epub 2011 Apr 6. — View Citation

Hirota K. Special cases: ketamine, nitrous oxide and xenon. Best Pract Res Clin Anaesthesiol. 2006 Mar;20(1):69-79. doi: 10.1016/j.bpa.2005.08.014. — View Citation

Kotsovolis G, Komninos G. Awareness during anesthesia: how sure can we be that the patient is sleeping indeed? Hippokratia. 2009 Apr;13(2):83-9. — View Citation

Lee, M. H., Fazli, S., Mehnert, J., & Lee, S. W. (2015). Subject-dependent classification for robust idle state detection using multi-modal neuroimaging and data-fusion techniques in BCI. Pattern Recognition, 48(8), 2725-2737. https://doi.org/10.1016/j.patcog.2015.03.010

Leon-Dominguez U, Izzetoglu M, Leon-Carrion J, Solis-Marcos I, Garcia-Torrado FJ, Forastero-Rodriguez A, Mellado-Miras P, Villegas-Duque D, Lopez-Romero JL, Onaral B, Izzetoglu K. Molecular concentration of deoxyHb in human prefrontal cortex predicts the emergence and suppression of consciousness. Neuroimage. 2014 Jan 15;85 Pt 1:616-25. doi: 10.1016/j.neuroimage.2013.07.023. Epub 2013 Jul 17. — View Citation

Levitt DG, Schnider TW. Human physiologically based pharmacokinetic model for propofol. BMC Anesthesiol. 2005 Apr 22;5(1):4. doi: 10.1186/1471-2253-5-4. — View Citation

Saadeh W, Khan FH, Altaf MAB. Design and Implementation of a Machine Learning Based EEG Processor for Accurate Estimation of Depth of Anesthesia. IEEE Trans Biomed Circuits Syst. 2019 Aug;13(4):658-669. doi: 10.1109/TBCAS.2019.2921875. Epub 2019 Jun 10. — View Citation

Sebel PS, Bowdle TA, Ghoneim MM, Rampil IJ, Padilla RE, Gan TJ, Domino KB. The incidence of awareness during anesthesia: a multicenter United States study. Anesth Analg. 2004 Sep;99(3):833-839. doi: 10.1213/01.ANE.0000130261.90896.6C. — View Citation

Sepulveda P, Cortinez LI, Irani M, Egana JI, Contreras V, Sanchez Corzo A, Acosta I, Sitaram R. Differential frontal alpha oscillations and mechanisms underlying loss of consciousness: a comparison between slow and fast propofol infusion rates. Anaesthesia. 2020 Feb;75(2):196-201. doi: 10.1111/anae.14885. Epub 2019 Dec 1. — View Citation

Sheahan CG, Mathews DM. Monitoring and delivery of sedation. Br J Anaesth. 2014 Dec;113 Suppl 2:ii37-47. doi: 10.1093/bja/aeu378. — View Citation

Sitaram R, Ros T, Stoeckel L, Haller S, Scharnowski F, Lewis-Peacock J, Weiskopf N, Blefari ML, Rana M, Oblak E, Birbaumer N, Sulzer J. Closed-loop brain training: the science of neurofeedback. Nat Rev Neurosci. 2017 Feb;18(2):86-100. doi: 10.1038/nrn.2016.164. Epub 2016 Dec 22. Erratum In: Nat Rev Neurosci. 2019 May;20(5):314. — View Citation

Yeom SK, Won DO, Chi SI, Seo KS, Kim HJ, Muller KR, Lee SW. Spatio-temporal dynamics of multimodal EEG-fNIRS signals in the loss and recovery of consciousness under sedation using midazolam and propofol. PLoS One. 2017 Nov 9;12(11):e0187743. doi: 10.1371/journal.pone.0187743. eCollection 2017. — View Citation

Zimeo Morais GA, Balardin JB, Sato JR. fNIRS Optodes' Location Decider (fOLD): a toolbox for probe arrangement guided by brain regions-of-interest. Sci Rep. 2018 Feb 20;8(1):3341. doi: 10.1038/s41598-018-21716-z. — View Citation

* Note: There are 15 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Brain electrophysiological activity by electroencephalography wavelength band powers	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)
Primary	Temporal brain oxygenation by near-infrared light spectroscopy wavelengths	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)
Primary	Levels of Consciousness with the Modified Ramsay Sedation Scale	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	BRICE survey responses	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

External Links

•   Kothe, C. (2014). Lab streaming layer (LSL)