Influence of Dexmedetomidine on a Closed-Loop Anesthesia System

Inclusion Criteria: * male patients scheduled for a general anesthesia Exclusion Criteria: * age lower than 18 years * allergy to propofol, or to soja or to peanuts, or to sufentanil, to remifentanil, or to morphine,or to a myorelaxant or to an excipient, * hypersensibility to sufentanil, or to remifentanil, or to other derivate of fentanyl, * history of central nervous system disease, * patients receiving a psychotropic treatment or an agonist-antagonist opiate, * hypovolemic patients, * patients receiving a cardio-vascular treatment, * expected bleeding surgical procedure, * simultaneous general and loco-regional anesthesia, * severe hepatic insufficiency.