The goal of this clinical trial is to learn how low tidal volume ventilation (LTV) and airway pressure release ventilation (APRV) affect lung tissue mechanics in adults with ARDS. The main questions it aims to answer are:

Does LTV or APRV improve lung tissue mechanics in patients with ARDS under mechanical ventilation? Researchers will compare LTV and APRV to see which ventilation mode works better for improving lung mechanics and patient safety.

Inclusion Criteria:

1. Meets the diagnostic criteria of the 2023 Global New Definition of ARDS.
2. Age: 18-80 years.
3. PaO2/FiO2 ≤ 200.
4. Within 12 hours of invasive mechanical ventilation treatment.
5. Obtain consent from the patient or their family members to participate in the study, and sign the informed consent form.

Exclusion Criteria:

1. Age < 18 years or > 80 years.
2. Uncorrected shock of any type.
3. Chronic obstructive pulmonary disease (COPD), pulmonary embolism, right heart failure, pulmonary hypertension, or severe arrhythmia.
4. Contraindications for using Electrical Impedance Tomography (EIT) (extensive chest skin damage, infection, pacemaker implantation, implanted automatic defibrillator, etc.), pneumothorax, mediastinal emphysema, or large pleural effusion.
5. Pregnant or breastfeeding women.
6. Patients planned for ECMO treatment.
7. Patients currently participating in or previously enrolled in other clinical studies.