The early phase of Acute Respiratory Distress Syndrome (ARDS) is characterized by intense alveolar inflammation. Corticosteroids have been used to treat ARDS for decades. Although their efficacy has been a subject of ongoing controversy, recent clinical practice guidelines for ARDS issued a weak recommendation in favor of corticosteroid use in early ARDS. However, the optimal dose and duration of corticosteroid therapy remain unclear. Low-dose, short-course regimens have been evaluated in clinical trials for severe pneumonia and COVID-19. However, no head-to-head comparisons have been conducted to evaluate the efficacy of prolonged versus short courses of corticosteroid therapy in ARDS.

To address this gap, the investigators designed a 3×2 factorial trial to assess corticosteroid therapy for ARDS, aiming to evaluate the effects of different doses (no steroid, medium-low dose, and medium dose) and durations (prolonged vs. short) on clinical outcomes. In addition, the investigators will measure changes in inflammatory biomarkers for post hoc analysis to explore whether these biomarkers could guide the selection of steroid regimens.

Inclusion Criteria:

• ARDS (as defined by the Berlin definition) with an FiO₂ of 0.5 or higher
• On invasive mechanical ventilation
• Duration of intubation less than three days

Exclusion Criteria:

• Age less than 18 years
• Required to receive steroids or considered ineligible for steroids by the primary care team
• Receiving systemic steroid therapy
• Uncontrolled gastrointestinal bleeding
• Uncontrolled infeciotn