CNAPContinuous Negative Abdominal Pressure in ARDS (CNAP in ARDS)

Inclusion Criteria:

1. Patients ≧ 18 years old
2. Patients with moderate to severe ARDS as per the Berlin definition (PaO2/FiO2 ≤200mmHg)
3. Patients with absence of any significant cardiopulmonary disease

Exclusion Criteria:

1. Contraindication to CNAP

a. open abdominal wounds or drainage tubes; b. Acute brain Injury with intracranial pressure >30 mm Hg or cerebral perfusion pressure <60 mmHg; c. Decompensated heart insufficiency or acute coronary syndrome; d. Major hemodynamic instability: Mean arterial pressure lower than 60 mm Hg despite adequate fluid resuscitation and two vasopressors or increase of vasopressor dose by 30% in the next 6 hours; f. Unstable spine, femur, or pelvic fractures; g. Pregnancy; h. Pneumothorax;
2. Contraindication to EIT electrode placement: Burns, chest wall bandaging limiting electrode placement
3. Severe liver insufficiency (Child-Pugh score > 7) or fulminant hepatic failure
4. Major respiratory acidosis or PaCO2 > 60 mmHg
5. Severe COPD (according to the GOLD criteria defined as severe = FEV1: 30-50% or very severe = FEV1 < 30%)
6. Clinical judgement of the attending physician