COMparative Performance of General Purpose Models

Inclusion Criteria: * Adult patients undergoing elective neurosurgical procedures with an expected sedation after surgery of \> 12 hours • Requirement for an arterial line Exclusion Criteria: * Pregnancy * Known sensitivity or allergy to propofol or remifentanil * Patient participating in research for which a period of exclusion is currently required by other study protocol, ethical committee or health authority. * Age \< 18 years old * Patients subjected to infusion of propofol and/or remifentanil not delivered through TCI pumps before the inclusion * Patients exposed to other sedatives (benzodiazepines, volatile anesthetics, quetiapine) before the inclusion