Effect of an Hypnotherapy Session on the NOL Variations After Stimulation

The investigators propose to evaluate the analgesic effect of medical hypnosis prior to the pharmacological induction of general anesthesia versus a classical pharmacological induction of anesthesia. Monitoring of the NOL index (Nociception index) as well as all the other classical parameters under general anesthesia (heart rate, blood pressure etc) will allow evaluation of the level of nociception related to oro-tracheal intubation as well as the one related to standardized electrical tetanic stimulation during general anesthesia and before surgical incision, between the two groups. The investigators know from the literature that the use of medical hypnosis in combination with anesthetic drugs allows for a significant reduction of hypnotic and opioid drugs. The investigators aim here at evaluating the real and objective impact of pre-anesthesia hypnosis on intraoperative nociception by using the NOL index which has been developed and used recently to better detect nociceptive stimuli under anesthesia. This clinical trial will provide an objective answer on the analgesic properties of intraoperative hypnosis. If this is confirmed, hypnosis could find its place in the management of perioperative nociception around general anesthesia.