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

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.