The study aims at deepen the proof level of sodium oxybate use for comfort sedation at the end of life in a palliative care unit by comparing it to midazolam in a prospective randomized study with blinded efficacy evaluation. The study will be carried out for a period of 24 months with a recruitment objective of 22 patients with refractory suffering and with a short-term prognosis.

In certain cases, terminally-ill patients may show persistent symptoms despite numerous efforts to find a comfort treatment without causing impaired consciousness. In these cases and after a collegial discussion, sedation may be offered.

Midazolam is then the most typically used sedative agent. However, it has limitations: frequent awakenings, tolerance and major respiratory depression. Furthermore, the use of midazolam as a "gold standard" in palliative sedation at the end of life falls under expert consensus without a high level of evidence.

Sodium oxybate (GammaOH®), is an ancient molecule used in anesthesia and other medical fields. It appears to be an attractive alternative to midazolam. Study hypothesis is as follows: deep sedation induced by sodium oxybate (RASS: -4 or -5) is more constant and sustainable than by using midazolam which can cause fluctuating effects and requires frequent dosage adjustments. The single-blind clinical trial aims at comparing the possibility to obtain constant deep sedation using midazolam or sodium oxybate. Before the induction, the patient is not aware of the medication used. The medical team must be aware of it because the two administration procedures are too different.

Inclusion Criteria:

• patient hospitalized in a palliative care unit
• patient aged 18 or over
• patient with an estimated vital prognosis of a few hours to a few days*
• patient with persistent suffering despite optimal palliative care*
• patient gave informed consent in advance or if unable to do so, consent given by a family member or legal representative (patients under guardianship)
• patient covered by a social security scheme. * Validated after collegial and multidisciplinary discussion including the opinion of a doctor outside the palliative care team.

Exclusion Criteria:

• contraindication or known allergy to sodium oxybate or midazolam
• significant risk of seizure
• venous access not possible
• pregnancy or breastfeeding
• person in exclusion period from another research protocol at the time of consent signing
• any condition which in the investigator's opinion could increase and jeopardize persons safety in case of research participation

Participants won't be aware of the sedative treatment administered.