Ultra-protective Ventilation Monitored by Electrical Impedance Tomography in Patients With Severe Acute Respiratory Distress Syndrome on Veno-venous ECMO

For ECMO supported patients with severe ARDS (acute respiratory distress syndrome), usual care include use of "ultraprotective" mechanical ventilation with tidal volume and pressure reductions that might ultimately enhance lung protection of patients with ARDS. Although very low tidal might also cause pulmonary derecruitment. The aim of this study is to monitor effects of very low tidal volume on regression of overdistension and derecruitment using electrical impedance tomography.Secondary aim is to describe the evolution of the optimal PEEP (Positive End Expiratory Pressure) during the decrease of the tidal volume

Inclusion Criteria:aged ≥ 18 yearspatient with ARDS on venovenous (VV)-ECMOWritten informed consentpatient affiliated to a social security schemeExclusion Criteria:PregnancyAdult patient subject to a legal protection measure (tutor, curator, etc.)Patients with a pacemaker, automatic implantable cardioverter defibrillator,contraindications to thoracic belt placement (e.g., thoracic or spinal cord trauma, recent thoracic surgery)undrained pneumothorax, bronchopleural fistulahemodynamic instability (i.e., use of intravenous fluids of more than 10 mL/kg or vasopressors 2 mg/h of norepinephrine or 0.5 mg/h of epinephrine)