Relationship Between the Depth of Anesthesia and Auditory Evoked Potentials (P3a)

Brief Summary

The interest of perioperative cerebral monitoring and in particular electroencephalography (EEG) to reduce neurological and cognitive damage in surgery has been the subject of abundant research and corresponds to a crucial issue. There is increasing evidence to suggest that inadequate (overdosed) anesthesia for patient characteristics and intraoperative hemodynamic instability is associated with an increased risk of complications including postoperative cognitive dysfunction and postoperative mortality. However, these devices have many limitations in use, in particular their consideration of the muscle component of the electrical signal collected.There are other identifiable EEG signals that can be used to assess the depth of anesthesia, in particular auditory evoked potentials (AEPs). The so-called rough sound waves correspond to a formulation composed of the rapid repetition of acoustic segments, at a frequency of 30 to 150 Hz.This frequency (whether sound or light) induces a temporal activation that captures attention and provokes unpleasant sensations and avoidance strategies when perceived by a subject. This project aims at overcoming the interaction of the muscular electrical signal by evaluating the electrophysiological response (auditory evoked potentials) to particular sound stimuli, called "rough", thus underpinning the understanding of the mechanisms of neurosensory integration and attention during a state of loss of consciousness or altered consciousness. The hypothesis proposed for this study is the following: the P3a wave (positive wave collected on the EEG during auditory evoked potentials) is altered during general anesthesia, in frequency and amplitude, and thus is indicative of the depth of the anesthetic state.