Mortality in Acute Respiratory Distress Syndrome (ARDS) is high (40 to 60 %). Protective mechanical ventilation is the cornerstone of the ARDS therapeutic strategies. Recently, a prospective multicenter study demonstrates that short-term infusion of neuromuscular blocking agents (NMBA) reduces hospital mortality. However, the mechanisms through which NMBAs could improve survival remain speculative and the dose of NMBA needed to observe a beneficial effect is still debated. In hypoxemic ventilated patients, continuous cisatracurium infusion with an objective of no response at orbicularis oculi to train-of-four (TOF) stimulation and an objective of two responses had similar effects on respiratory parameters. In their study, Papazian and colleagues used cisatracurium with an initial standard dose of 15 mg followed by a continuous infusion of 37.5mg/h, based on previous results of studies with patients monitored for paralysis. Atracurium and its stereoisomer cisatracurium are non-depolarizing neuromuscular blocking drugs, both used in anaesthesia and intensive care units.

The aim of this study was to compare in ARDS patients a dose adjustment of continuous-atracurium intravenous infusion with an end point of one or two response at orbicularis oculi to TOF stimulation, and a dose adjustment to achieve clinical goals of protective ventilation without monitoring of TOF stimulation.

Inclusion Criteria:

• ARDS with a PaO2 / FiO2 < 200 with a PEEP > 5 since less than 48 hrs
• Informed consent

Exclusion Criteria:

• NMBA allergy
• Continuous administration of NMBA for ARDS prior inclusion
• Age < 18 yrs