Relationship Between the Level of Positive End-expiratory Pressure and Venous Congestion During Acute Respiratory Distress Syndrome.

Inclusion Criteria: * Patients hospitalized in the Medical Intensive Care and Hyperbaric Medicine Unit of Angers University Hospital, receiving mechanical ventilation in assist-control mode (A/C ventilation), and presenting with ARDS as defined by the following criteria (1): * Hypoxemia with a PaO₂ (mmHg)/FiO₂ (0.21 to 1.0) ratio \<300 mmHg with a positive end-expiratory pressure (PEEP) ≥5 cmH₂O; * Pulmonary edema not fully explained by cardiac failure or fluid overload; * Presence of bilateral pulmonary opacities on chest imaging not fully explained by pleural effusions, atelectasis, or pulmonary nodules. Exclusion Criteria: * Minor patient (\<18 years old) * ECMO (Extracorporeal Membrane Oxygenation) * Hemodynamic instability (mean arterial pressure \<60 mmHg) * Respiratory instability (SpO₂ \<90% under FiO₂ \>90%) * Severe organic tricuspid regurgitation * Congenital heart disease * Pneumothorax * Renal or hepatic transplant recipient * Liver cirrhosis Child-Pugh C * Portal vein thrombosis or Budd-Chiari syndrom * Abdominal compartment syndrome documented by intra-abdominal pressure ≥20 mmHg * Pregnant, breastfeeding, or peripartum women * Persons deprived of liberty by judicial or administrative decision * Persons subject to compulsory psychiatric care * Persons under legal protective measures