Dexmedetomidine in Mechanically Ventilated Neonates With Single-Organ Respiratory Failure.

Inclusion Criteria: * patient age less than 1 month (Male/Female) (step-down strategy for age) * first included patients (n=30): postmenstrual age \>= 34 weeks (near-term neonates) * following included patients (n=30) : postmenstrual age \>= 25 weeks and \< 34 weeks (preterm neonates) * patients with single-organ respiratory failure in need for analgosedation (guidance : Comfort neo score \>14 or Numeric Rating Scale (NRS) score Pain (P)/Comfort (C)\>4) * patients admitted to the neonatal intensive care unit * expected to require at least 20 hours of mechanical ventilation Exclusion Criteria: * patients with neurologic conditions that prohibit an evaluation of adequate analgosedation * no arterial catheter in place at inclusion * patients who have received another investigational drug within 30 days * patients on continuous infusion with neuromuscular blockers * patients with a life expectancy \<72 hours * patients with a known allergy to fentanyl * congenital or acquired heart block (grade 3) * sustained bradycardia * haemodynamically unstable patients (definition : Mean Arterial Pressure (MAP) lower than : postmenstrual age (in weeks) - 5 millimeter Hg, eventually under dopamine infusion max. 16 mcg/kilogram/minute and/or dobutamine infusion maximal 16 mcg/kilogram/minute) * patients with significant renal insufficiency (creatinine plasma level \>1.5 milligram/deciliter) * patients with significant hepatic insufficiency (as estimated by local investigators) * previous treatment with α2-adrenoreceptor agonist clonidine within 14 days * absence of parental consent