•  Defined clinically by the Berlin modification of the American European Consensus Committee (AECC) definition and criteria:


“An acute diffuse inflammatory lung injury, leading to increased pulmonary vascular permeability, increased lung weight and loss of aerated tissue with hypoxemia and bilateral radiographic opacities and associated venous admixture, increased physiological dead space and decreased compliance.”  

  • ARDS is diagnosed clinically using the international consensus criteria (The Berlin Criteria)
  • Essential components required for diagnosis are:
    1. PaO2/FiO2 ratio of ≤300
    2. Acute onset (within 1 week of known clinical insult)
    3. Bilateral opacities on CXR (not explained by effusions, collapse, or nodules)
    4. Respiratory failure not fully explained by heart failure or fluid overload (objective assessment such as echocardiogram recommended if no risk factor)


  • The histological correlate for ARDS is known as ‘diffuse alveolar damage’:
    • Considered the gold standard for diagnosis
    • Rarely used as requires an open lung biopsy