Radiographic Phenotype

ARDS was first defined by Ashbaugh in 1967. Several other definitions have been introduced afterwards up to the American-European Consensus Conference (AECC) in 1994. This defines ARDS as the acute onset of hypoxemia (PaO2/FiO2 ≤ 200) with bilateral infiltrates at x-rays and no evidence of left atrial hypertension and was largely used for the enrollment of patients in clinical trials. In 2011 a panel of experts, under the initiative of the European Society of Intensive Care Medicine endorsed from the American Thoracic Society and Society of Critical Care Medicine, convened to develop what has been called the “Berlin definition”. The main difference introduced is the separation, within the older ARDS, of moderate and severe forms, i.e. back to the oldest Ashbaugh definition: refractory hypoxemia. Stages of mild, moderate and severe ARDS were associated to increased mortality and increased median duration of mechanical ventilation in survivors. We found that Moderate and Severe ARDS differ because of: Lung weight (edema); Well inflated tissue (baby lung dimension); Not inflated tissue (extent of injured lung); Recruitability (spreading of lung injury) and ICU outcome.