Effects of Dexmedetomidine on Delirium Duration of Non-intubated ICU Patients (4D Trial)

Inclusion Criteria: * • Age \> 18 years * Patient hospitalized in an ICU * Presenting a productive delirium according to the following criteria: * acute onset (\<2h) and fluctuating course during the same day * alteration of cognitive functions: disorganization of thought (delirium of persecution, inability to reason logically), abnormal perceptions (hallucinations), memory impairments, temporal disorientation, non- or misrecognitions, difficulties in naming objects or writing) * in whom a simple cropping and non-medicated therapeutics are not sufficient to allow symptoms' resolution for few hours * CAM-ICU positive AND a RASS \> +1 * Non-intubated or extubated (\> 24h) * No contraindication of dexmedetomidine or haloperidol uses Exclusion Criteria: * • Age \<18 years * Administration of dexmedetomidine and/or clonidine during the 72 hours before inclusion * Contraindication to the use of Dexmedetomidine, clonidine or haloperidol (history of allergy, Parkinson's disease, oro-pharyngeal dysfunction, arterial hypotension or bradycardia, QTc interval prolongation, and hepatic or renal dysfunction), as mentioned in the Summaries of Product Characteristics * Neuropsychiatric pathology judged by the investigator as a potential source of bias (in particular: active drug addiction, psychosis...) * Parturient or breast-feeding woman * Protected major (guardianship) * Patient's or relative's refusal to participate