Automatic Remifentanil Administration Guided by ANI During Propofol Anesthesia

Prospective Randomized Monocentric Clinical Trial during propofol anesthesia. * inclusion: ASA 1, 2 or 3 adult patients scheduled to undergo burn wound surgery in a Burn Center (University Hospital of Lille, France) * arm 1 : Remifentanil will be automatically administered by an expert system guided by heart rate, blood pressure and the Analgesia Nociception Index (ANI). * arm 2 : Remifentanil will be administered by a target controlled device using the Minto pK/pD model. * propofol is administered throughout the procedure with a target controlled device using the pK/pD model of Schnider. The target will be guided by the BiSpectral index values. * primary endpoint : overall normalized remifentanil administration. * secondary endpoints : relative amount of time spent in a state of hemodynamic reactivity ; relative amount of time the ANI spends in the \[0-50\], \[50-70\] and \[70-100\] windows ; relative amount of time the BIS spends in the \[0-40\], \[40-60\] and \[60-100\] ; hemodynamic status at various times during anesthesia ; total amount of target modifications of remifentanil and propofol ; total amount of morphine administered in PACU ; total amount of ketamine administered in PACU ; incidence of nausea/vomiting in PACU ;