Impact of Chronic Treatment by β1-adrenergic Antagonists on Nociceptive-Level (NOL) Index Variation After a Standardized Noxious Stimulus Under General Anesthesia

"50 adult patients undergoing general anesthesia for any types of surgery and who have been chronically treated with β1-adrenergic antagonists for at least three months. .Induction of anesthesia will be standardized.~At least 10 min after the post-intubation decrease of the remifentanil infusion rate, the OR team will stop any physical contact/stimulation of the patient allowing at least 3-minutes.~At this point, the standardized electrical (tetanic) stimulation will be applied on the area of the ulnar nerve at the wrist level, at a frequency of 100 Hz and a current of 70 mA for a duration of 30 seconds, followed by 3 minutes of observation period without any other stimulation of the patient by the anesthesia or the surgical team. At the end of the observation period, the study is discontinued and the anesthesia will be conducted at the discretion of the anesthesiologist in charge of the patient."