Interest of the Study of Electroencephalogram and Peripheral Vegetative Markers for the Evaluation of Nociception Under General Anesthesia.

Study Overview
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Brief Summary
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General anesthesia (GA) is a state of loss of consciousness induced by anesthetic products. In a GA, two classes of products are usually used: on the one hand, hypnotics that are responsible for the sleep component (hypnosis) and memory loss (amnesia), and on the other hand opioids that have an analgesic role. The doses of hypnotic and morphine necessary to achieve this state of loss of consciousness and lack of response to painful stimulation vary from subject to subject, and during surgery depending on the intensity of the stimulus, requiring permanent adaptation to avoid overdose or underdosing, responsible for morbidity. Several monitors of the hypnotic component have been developed in recent years, which can now be used routinely, such as the Bispectral Index (BIS) or Spectral Entropy. However, there is currently no clinically validated technique for monitoring pain or the effect of opioids in the operating room. Spectral analysis of the electroencephalogram (EEG) revealed a significant decrease (-30%) in alpha spectral power, observed specifically in painful experimental conditions in healthy awake subjects. On the other hand, a painful experience is accompanied by transient changes in various parameters under vegetative control, whether cardiovascular, cutaneous or pupillary, essentially underpinned by the activation of the sympathetic system. The investigators hypothesize that a real-time dynamic analysis of the spectral power of EEG combined with that of cardiovascular vegetative parameters, cutaneous conductance and pupillary diameter is likely to be a marker of nociception under GA.

Official Title
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Interest of the Study of Electroencephalogram and Peripheral Vegetative Markers for the Evaluation of Nociception Under General Anesthesia.

Conditions
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General Anesthesia

Intervention / Treatment
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* Device: Experimental group


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient affiliated or entitled to a social security scheme Over 18 years old To be operated on a regulated surgery allowing access to the head and to one eye, under AG, in the operating theater of the CHU of Saint-Etienne And having given his free, informed, written and signed consent. Exclusion Criteria: Subject to a measure of legal protection (tutelage, guardianship) Admitted for emergency surgery With known allergy to any of the anesthetic agents used in the study Having been asleep under general anesthesia in the 7 days preceding the intervention A pacemaker or heart transplant patient With a history of Parkinson's disease, insulin-dependent or non-insulin-dependent diabetes at a dysautonomic stage or chronic alcoholism at a dysautonomia stage With psychiatric history or severe depression Presenting a peripheral or central neurological pathology that may modify the physiological responses to nociceptive stimulation With abnormal heart rhythm (atrial fibrillation or frequent extrasystoles) Treated for arterial hypertension with angiotensin type 2 receptor antagonists Treated with anti-arrhythmic, α- or β-blocking, which would make the interpretation of the results more difficult With chronic pain Treated with morphine or long-term neuroleptic Consuming cannabis or another narcotic Presenting bilateral ocular pathology that may interfere with pupillary dilatation Or refusing to participate in the study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Interventional Model Description: This is a monocentric and prospective observational study on the physiology of nociception under general anesthesia. The patient will be his own witness.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental group<br>Patients under general anesthesia will be included. | Device: Experimental group<br>* EEG acquisition system BioSemi (Amsterdam, the Netherlands), enabling real-time measurement and continuous recording of EEG on up to 128 leads.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ElectroEncephaloGram (EEG) Alpha spectral power | variations of the EEG parameters (spectral power of the alpha rhythms), during nociceptive stimuli performed under AG at constant hypnosis depth (BIS between 50 and 60), without and after injection of a standardized dose of morphine (0.2 μg / kg of sufentanil based on the theoretical weight) of the patient). | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Beta spectral power | variations of the EEG parameters (spectral power of the beta rhythms), during nociceptive stimuli performed under AG at constant hypnosis depth (BIS between 50 and 60), without and after injection of a standardized dose of morphine (0.2 μg / kg of sufentanil based on the theoretical weight) of the patient). | 1 day | 
| gamma spectral power | variations of the EEG parameters (spectral power of the gamma rhythms), during nociceptive stimuli performed under AG at constant hypnosis depth (BIS between 50 and 60), without and after injection of a standardized dose of morphine (0.2 μg / kg of sufentanil based on the theoretical weight) of the patient). | 1 day | 
| delta spectral power | variations of the EEG parameters (spectral power of the delta rhythms), during nociceptive stimuli performed under AG at constant hypnosis depth (BIS between 50 and 60), without and after injection of a standardized dose of morphine (0.2 μg / kg of sufentanil based on the theoretical weight) of the patient). | 1 day | 
| theta spectral power | variations of the EEG parameters (spectral power of the tetha rhythms), during nociceptive stimuli performed under AG at constant hypnosis depth (BIS between 50 and 60), without and after injection of a standardized dose of morphine (0.2 μg / kg of sufentanil based on the theoretical weight) of the patient). | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Free Head, General anesthesia, Surgery