Evaluation of the Diagnostic Performance of Electrical Impedance Tomography to Detect Situations at Risk of Lesions Induced by Conventional Mechanical Ventilation in ARDS

Inclusion criteria

• Aged ≥18 years
• Hospitalised in the medical resuscitation department of the Croix Rousse hospital, Lyon, Fr
• With ARDS according to the 1994 American-European Consensus Conference
• Duration of ARDS less than 96 hours
• With invasive mechanical ventilation
• With sedative and analgesic treatment for adaptation of the respirator with or without neuromuscular blocking agents
• Consent obtained from patient family
• Indication for thoracic scanner as judged by the physician in charge of the patient

Exclusion criteria

• Excessively serious respiration precluding the modifications to ventilation planned in the protocol

• severe hypoxemia defined as sever by arterial blood pressure/fraction of inspired oxygen (PaO2/ FiO2) below 100 mm Hg in dorsal decubitus position
• uncontrolled respiratory acidosis, defined by a pH below 7.25, despite an increase of respiratory frequency up to 35/min and a tidal volume up to 8 mL/kg of predicted weight
• respiratory system plateau pressure higher than 30 cm H2O, with a tidal volume below or equal to 6 mL/kg of predicted weight.
• Contraindication for transport to the radiology department

• uncontrolled hemodynamic instability defined by a mean arterial blood pressure below 65 mm Hg, despite use of antihypotensive agents
• patient requiring continuous dialysis without possibility for disconnection for reason of uncontrolled metabolic acidosis (pH<7.20).
• Without reliable monitoring during transport of the patient to the radiology department

• absence of invasive arterial pressure measurement
• unreliable measurement of arterial saturation in oxygen (SpO2) defined by a perfusion index below 0.5.
• Intracranial hypertension
• Impossible to apply EIT electrodes on the thorax of the patient (burns, dressings, …)
• Undrained pneumothorax or bronchopleural fistula
• Scanner unavailable for the study (broken down, overloaded program, …)
• Contraindication esophageal balloon catheter

• Known or suspected esophageal disease (tumor, esophageal varices, esophagitis, diverticulum, ...)
• Latex allergy
• Patient previously included in the study
• Vulnerable persons (as defined in laws L1121-5 to L1121-7, L1121-8 and L1122-1-2