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

Brain function monitoring using a Sedline® module (Masimo corporation) to evaluate the state of the brain under anesthesia

Monotonous sounds are sent via binaural headphones: a standard item and a distractor item (rough sound). Each stimulus lasts about 300 ms and they are separated by 1.5 to 2 seconds between them; the deviant sound/standard sound ratio is fixed between 1/5 and 1/6.

Measurement of cerebral blood flow velocity (CFV) with use of Transcranial Doppler ultrasonography. For all patients, CFV (unit cm/s) will be collected over four distinct periods: 1/ baseline or during pre-oxygenation at inspired oxygen fraction (FiO2) of 21% in awake patients; 2/ during anesthetic induction; 3 /deep sleep; 4/ recovery period.

"Continuous measurement of cerebral oxygen saturation (SO2) with Near-infrared spectroscopy (NIRS).~For all patients, SO2 (%) will be collected over four distinct periods: 1/ baseline or during pre-oxygenation at FiO2 of 21% in awake patients; 2/ during anesthetic induction; 3 /deep sleep; 4/ recovery period."