Acute respiratory syndrome distress (ARDS) is a clinical common syndrome with high mortality. Mechanical ventilation (MV) is the cornerstone of management of ARDS but can lead to ventilator-induced lung injury. Positive end-expiratory pressure (PEEP), as one of main component of MV, has been widely used in the clinical practice. However, the PEEP selection is still a difficult problem for moderate to severe ARDS patients. EIT, an imaging tool evaluating the regional ventilation distribution at the bedside, can achieve the individual PEEP selection for all mechanically ventilated patients. Our previous study found that moderate to severe ARDS patients with higher recruitability could benefit from EIT-guided PEEP. This article compared the effect of PEEP titrated guided by EIT with fraction of inspired oxygen (FiO2)-PEEP table on the clinical outcomes in ARDS patients.

Inclusion Criteria:

1. Age≥18 years
2. Moderate-to-severe ARDS, defined by the ARDS Definition Task Force in the Berlin definition (partial pressure of arterial oxygen [PaO2]:FiO2 ratio ≤200 mmHg with a PEEP ≥5 cmH2O)
3. Diagnosis of ARDS less than 72 hours

Exclusion Criteria:

1. Expected to be mechanically ventilated for less than 48 hours
2. Severe chronic respiratory diseases requiring long-term home oxygen therapy or noninvasive MV
3. Undrained pneumothorax or subcutaneous emphysema
4. Contraindication to the use of EIT (pacemaker, automatic implantable cardioverter defibrillator, and implantable pumps)
5. Severe neuromuscular disease
6. Hemodynamic instability
7. Contraindications to hypercapnia, such as intracranial hypertension or acute coronary syndrome
8. Severe other organs dysfunction with a low expected survival (7 days) or palliative care
9. Severe liver disease (Child-Pugh Score ≥10)
10. Pregnancy
11. Refusal to sign the informed consent