EARLY-SARDS: Early AlveolaR Lung biologY Underling Sepsis-Associated ARDS

Sepsis-associated acute respiratory distress syndrome (ARDS) remains a major cause of respiratory failure and mortality in critically ill patients. Although only a proportion of patients with sepsis develop ARDS, early identification of those at highest risk remains a major unmet clinical need. Current prediction relies largely on clinical deterioration and oxygenation impairment, which often occur when lung injury has already developed. Increasing evidence suggests that biological responses to sepsis are compartmentalized between the systemic circulation and the alveolar space, while early abnormalities in respiratory mechanics and ventilatory efficiency may provide complementary information on evolving lung injury. However, no prospective study has integrated serial systemic and alveolar biomarkers with bedside respiratory physiology during the earliest phase of sepsis-associated respiratory failure. EARLY-SARDS is a prospective observational cohort study designed to characterize the early biological and physiological trajectories of invasively ventilated patients with sepsis or septic shock. Serial bronchoalveolar lavage (BAL) and plasma samples, together with standardized measurements of respiratory mechanics and gas exchange, will be collected during the first 96 hours after enrollment. The primary objective is to develop an integrated biological-physiological model capable of predicting ARDS development and subsequent peak ARDS severity. Secondary objectives include characterizing biological compartmentalization, identifying integrated biological-physiological subphenotypes, and evaluating their association with clinically relevant outcomes, including duration of mechanical ventilation, ventilator-free days, need for extracorporeal respiratory support, ICU length of stay, and mortality.