The Superior Vena cava Respiratory Collapse Index (cVCS) is a haemodynamic parameter measured exclusively by transoesophageal ultrasound (TEE), which is used to assess cardiac precharge-dependence status. This may be an important prognostic factor in ARDS because it is a sign of hypervolemia and right heart failure.

Inclusion Criteria:

• Patients hospitalized in Resuscitation, Emergency or Intensive Care Units at the Roger Salengro Hospital at Lille University Hospital.
• With acute respiratory distress syndrome of intermediate or severe severity (1) for less than 24 hours.
• Mechanical ventilation with tracheal intubation or tracheostomy, in controlled assisted ventilation (VAC) mode.
• Patient adapted to mechanical ventilation (no triggering of spontaneous ventilation cycle in VAC mode verified by the equality between the respiratory rate prescribed on the ventilator and the actual respiratory rate of the patient).

Exclusion Criteria:

• Patient under extracorporeal respiratory assistance at the time of inclusion.

• Anomalies or pathologies that make it dangerous or impossible to introduce an ETO probe:

  • Fistula, perforation, stenosis, varicose vein or diverticulum of the esophagus and / or stomach
  • History of esophageal and / or gastric surgery
  • Caustic lesions of the esophagus and / stomach
  • Tumor or history of oropharyngeal surgery
  • Unstable lesions of the cervical spine
  • Coagulopathy (thrombocytopenia <50 109 / L and / or TP <50%).

• Impossibility of measuring the diameter of the superior vena cava and cVCS in ETO due to poor echogenicity.

• Pregnant woman.

• Therapeutic limitation measures limiting the treatment of organ failure.

patients with mechanical ventilation hospitalized in intensive care, emergency or intensive care units