Lung EIT Image Guide Ventilation in ARDS

Inclusion Criteria: * Patients with ARDS receiving mechanical ventilation who meet the following diagnostic criteria: 1. Triggered by acute risk factors such as pneumonia, non-pulmonary infection, trauma, transfusion, aspiration, or shock. Pulmonary edema is not entirely or predominantly attributable to cardiogenic causes or fluid overload, and hypoxemia/gas exchange impairment is not mainly due to atelectasis. However, ARDS can be diagnosed in the presence of these conditions if predisposing risk factors exist. 2. Acute onset or worsening of hypoxemic respiratory failure within 1 week of the identified risk factor or onset of new or worsening respiratory symptoms. 3. Bilateral opacities on chest radiograph or CT, or bilateral B-lines and/or consolidation on ultrasound, not fully explained by effusion, atelectasis, or nodules/masses. 4. PaO₂/FiO₂ ≤ 300 mm Hg or SpO₂/FiO₂ ≤ 315 (if SpO₂ ≤ 97%). * ARDS onset within 1 week. * Mechanical ventilation ≤ 72 hours. Exclusion Criteria: * Age \< 18 years. * Pregnancy. * Contraindications to EIT application (e.g., local skin lesions, cardiac pacemaker). * Contraindications to prone positioning (e.g., increased intracranial pressure, intra-abdominal hypertension, spinal fractures). * Evidence of barotrauma such as pneumothorax, mediastinal emphysema, or subcutaneous emphysema. * End-stage disease. * Informed consent not signed by legal guardians or family.