Neural Mechanisms of Sevoflurane Induced Anesthesia: an EEG fMRI Study in Healthy Volunteers

Study Overview
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Brief Summary
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In imaging functional connectivity (FC) analyses of the resting brain, alterations of FC during unconsciousness have been reported. These results are in accordance to recent electroencephalographic studies observing impaired top-down processing during anesthesia. In this study, simultaneous records of functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) were performed to investigate the causality of neural mechanisms during sevoflurane anesthesia by correlating FC in fMRI and directional connectivity (DC) in electroencephalogram.

Conditions
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Anesthesia, Drug Effects

Intervention / Treatment
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* Drug: Sevoflurane


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA I male age > 18y Exclusion Criteria: drug abuse history of psychiatric or neurologic diseases amblyacousia, deafness contradictions to the study drug (sevoflurane) implants piercings, tatoos

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sevoflurane<br>Single arm: dose escalation of study medication | Drug: Sevoflurane<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of information processing (entropy) in EEG and functional connectivity (BOLD ICA and small group network architecture) in fMRI during sevoflurane anesthesia at states awake, 2vol%, 3vol% and EEG endpoint burst suppression | Changes of fMRI functional connectivity and of EEG information processing during different levels of sevoflurane anesthesia from wakefulness to deep anesthesia: At each anesthetic level at equilibrated states awake, 2vol%, 3vol% and EEG endpoint burst suppression, EEG and fMRI are recorded simultaneously for about 10 minutes. For each level EEG and fMRI connectivity analysis are performed using the recording length of 10 minutes. This results in one outcome parameter for EEG and fMRI connectivity. Furthermore, both modalities are combined resulting in one combined parameter for each level. For EEG analysis permutation entropy as a measure of information content in EEG, and symbolic transfer entropy as a measure of directed interaction in EEG are used. fMRI functional connectivity analysis is based on BOLD ICA and on network analysis of the BOLD time series. | 10 minutes for each condition | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of the brain network structure during recovery in EEG and fMRI | Identical technical setup than main outcome | 10 minutes for each condition | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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EEG, fMRI, connectivity, sevoflurane