Comparison of an Inhaled Sedation Strategy to an Intravenous Sedation Strategy in Intensive Care Unit Patients Treated With Invasive Mechanical Ventilation

Inclusion Criteria: * Patient aged 18 and over * Patient requiring mechanical ventilation for at least 24 hours * The patient requires continuous and immediate sedation for more comfort, safety and to facilitate the administration of survival measures. * Consent obtained from patient or relative Exclusion Criteria: Patient hospitalized for the following reasons for admission: * Cardiac arrest * State of refractory epilepticus * Head trauma * Stroke * Hearing, visual or aphasia disorders before inclusion making it impossible to take the CAM-ICU * Sedation started more than 24 hours ago * Impairment of cognitive functions and / or dementia * Contraindication to halogenated gases (personal or family history of malignant hyperthermia, acute or chronic neuromuscular disease, hepatocellular insufficiency with PT \<30%) * Severe acute respiratory distress syndrome (ARDS) (Berlin criteria: PaO2 / FiO2 \<100 after ventilatory optimisation)) * PaCO2 at inclusion\> 50 mmHg after ventilatory optimisation * Patient for whom a procedure of "limitation of active therapies" is envisaged at inclusion * Patient under guardianship or curatorship * Minor patient * Pregnant or breastfeeding woman * Patient not affiliated to the social security scheme