Despite the increasing use of non-invasive ventilation, a large majority of premature neonates still receive invasive ventilation during their NICU (neonatal intensive care unit) stay. Invasive ventilation is a unanimous source of discomfort and pain.

As opposed to the adult and pediatric population, routine use of opioids or midazolam is not recommended in ventilated neonates.

Although opioids are the most frequently prescribed analgosedative drugs in ventilated premature neonates, their use is controversial because of the risk of respiratory depression - which can prolong invasive ventilation- and concerns on long-term neurodevelopment.

Dexmedetomidine, a selective alpha-2- adrenergic agonist routinely used in the adult ICU (intensive care unit), provides light sedation and some analgesia with no or little respiratory-depression effect. It also has neuroprotective properties after pediatric cardiac surgery and in neonatal animal models. Dexmedetomidine is thus a promising candidate drug in ventilated premature neonates that might reduce the duration of mechanical ventilation and preserve neurodevelopment in this vulnerable population.

The investigators hypothesize that the use of dexmedetomidine in ventilated premature neonates could decrease the need for opioids, facilitate extubation and thereby preserve long-term neurodevelopmental outcome.

Above mentioned age limits (0 -10 weeks) apply to postnatal age. Inclusion criteria apply to gestational age at birth and postmenstrual age (in weeks).

Inclusion Criteria:

• Neonates with a gestational age at birth < 32 weeks of gestation and corrected gestational age < 32 weeks postmenstrual age
• Invasively ventilated with an expected or effective duration of ventilation > 24 hours at inclusion
• Under mechanical ventilation since less than 72 hours at inclusion
• With parental consent
• Affiliated to or benefiting from a social security system

Exclusion Criteria:

• Previous inclusion in this trial
• Participation in another trial including analgesics or sedatives
• Ongoing palliative care
• Administration of dexmedetomidine or another alpha-2 agonist in the 96 previous hours
• Hemodynamic compromise defined as any of: poor perfusion (increased capillary refill time, oliguria); hypotension defined as a mean blood pressure in mm Hg < postmenstrual age in weeks; ongoing inotropic treatment with dopamine or dobutamine ≥ 5 µg/kg/min, or any other inotropic drug at any dose, or need for more than one volume expansion (20 ml/kg) in the 6 previous hours
• Pulmonary hypertension requiring pharmacological treatment
• Heart rate <100 bpm
• Hepatic impairment defined as alanine aminotransferase level > 2 x normal upper limit
• Known contra-indications to dexmedetomidine: hypersensitivity, atrioventricular block, acute cerebrovascular event
• Hypersensitivity to the active substance or to any of the excipients contained in the medicine

Use of similar vials and labels for the 2 allocation arms. Masking of the result of randomization (arm description) in the eCRF. Only the treatment unit number will appear on the eCRF for administration.