Inclusion Criteria:  Age≥18 years 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) Diagnosis of ARDS less than 72 hours  Exclusion Criteria:  Expected to be mechanically ventilated for less than 48 hours Severe chronic respiratory diseases requiring long-term home oxygen therapy or noninvasive MV Undrained pneumothorax or subcutaneous emphysema Contraindication to the use of EIT (pacemaker, automatic implantable cardioverter defibrillator, and implantable pumps) Severe neuromuscular disease Hemodynamic instability Contraindications to hypercapnia, such as intracranial hypertension or acute coronary syndrome Severe other organs dysfunction with a low expected survival (7 days) or palliative care Solid organ or hematologic tumors with the expected survival time less than 30 days Participating in other clinical trials within 30 days Pregnancy Refusal to sign the informed consent