What is the hallmark sign of Acute Respiratory Distress Syndrome?

The hallmark sign of Acute Respiratory Distress Syndrome (ARDS) is non-cardiogenic pulmonary edema leading to hypoxemia. ARDS is a severe respiratory disorder characterised by widespread inflammation and fluid accumulation in the lungs. The increased permeability of the lung capillaries results in the leakage of protein-rich fluid and cellular components into the alveolar air spaces, causing significant impairment in gas exchange.