COMparative Performance of General Purpose Models

To compare the performance of the Eleveld models for propofol and remifentanil on neurosurgery patients admitted to intensive care with their intraoperative performance.

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