The procedure for recording data and obtaining the pharmacokinetics/pharmacodynamics (PK / PD) model will be connecting a SEDLine® monitor to a laptop with an original program developed by members of our team. The program automatically stores the infusion rate of propofol (mg/kg/h) and the simultaneous values of PSI and frontal EMG. Graphics and data collected will be explored with various systems of techniques for pattern recognition in order to get the best fit to define a mathematical model of the dose of propofol and PSI values. A subsequent computer analysis with MATLAB® will estimate the correlation between the infusion of propofol infusion rate and PSI values.