The goal of this multi-center randomized controlled clinical trial is to learn if an individualized, bedside electrical impedance tomography (EIT)-guided ventilation strategy (including EIT-guided prone positioning and PEEP titration) can improve outcomes compared with a conventional lung-protective ventilation strategy in adult patients with acute respiratory distress syndrome (ARDS).

The main questions it aims to answer are:

Does the individualized EIT-guided ventilation strategy reduce 28-day mortality in ARDS patients? Researchers will compare the EIT-guided intervention arm to a control arm receiving routine lung-protective ventilation (without bedside EIT guidance) to see if the EIT-guided approach lowers 28-day mortality and improves other clinical outcomes.

Adult ARDS patients who meet inclusion criteria will be assigned to EIT-guided group and control group through stratified randomization:

EIT-guided group: Undergo bedside EIT assessments using a China-manufactured EIT device to guide decisions about prone positioning and individualized PEEP titration (including a recruitment maneuver).

Control group: Receive PEEP setting per conventional PEEP-FiO₂ tables and prone positioning per standard clinical indications without EIT guidance.

Both groups: Receive standard supportive ICU care and routine outcome assessments at multiple time points.

Primary outcome: 28-day mortality. Other outcomes include ventilator-free days to day 28 and so on.

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.