"Continuous Positive Airway Pressure on Venovenous extracorporeaL Membrane Oxygenation for Acute respIratory Distress syndrOme"

Inclusion Criteria: 1. Severe acute respiratory distress syndrome refractory to conventional therapy placed on VV-ECMO support in the 48 hours (maximum tolerance : +2h) preceding inclusion. 2. Obtain informed consent from a close relative or surrogate. According to the specifications of emergency inclusion, randomization without the close relative/surrogate consent could be performed if the patient is unable to give his/her consent and when the close relative/surrogate/family member are absent. Close relative/surrogate/family member consent will be asked as soon as possible after randomization. The patient will be asked as soon as possible to give his/her consent for the continuation of the trial when his/her condition will allow. 3. French Social security registration (except AME) Exclusion Criteria: 1. Age \< 18 2. Pregnancy or breastfeeding 3. Initiation of VV-ECMO \> 48 h (maximum tolerance : +2h) 4. Cardiac arrest with cumulated no flow time \&amp;gt;10 minutes before ECMO (within 48 hours prior to inclusion) 5. Irreversible neurological pathology 6. End-stage chronic lung disease 7. Contraindications for high PEEP level: untreated pneumothorax, barotrauma 8. Irreversible ARDS with no hope for lung function recovery 9. Patient moribund on the day of randomization, SAPS II \&amp;gt;90 10. Liver cirrhosis (Child B or C) 11. Lung transplantation 12. Burns on more than 20 % of the body surface 13. Participation in another interventional study with a similar primary endpoint (mortality, lung transplantation, or duration of ECMO) or being in the exclusion period at the end of a previous study 14. Individuals under guardianship, or permanently legally incompetent adults