Mortality in Acute Respiratory Distress Syndrome is high (40 to 60 %). Protective mechanical ventilation, until 2010, was the cornerstone of the ARDS therapeutic strategies. Recently, a prospective multicenter study demonstrates that a 48h continuous infusion of neuromuscular blocking agents (NMBA) have a positive impact on mortality of ARDS patients. (Papazian et al. ACURASYS Study. NEJM 2010; 363:1107-16). The mechanisms through which NMBAs could improve survival remain speculative. They are as follows:

• reduction of the consumption of oxygen linked to ventilatory workload;
• increase of chest wall compliance improving mechanical ventilation during ARDS and better adaptation to the protective ventilation strategy;
• anti-inflammatory effect contributing to a reduction in pulmonary inflammation and improvement in oxygenation,
• reduction of the variations of transpulmonary pressure (TPP) by the way of better synchronisation between patient and the ventilator.

The use of NMBA could also reduce the ventilator induced lung injury by a better control of TPP.

Inclusion Criteria:

• Early (< 48H) Severe ARDS: PaO2 / FiO2 ratio < 150 with PEEP >= 5 cmH20

Exclusion Criteria:

Age < 18 ans Patient already under continuous infusion NMBA. Known NMBA Allergy or intolerance Contra-indication to introduction of nasogastric tube