Definition of Acute Lung Injury (ALI) & Acute Respiratory Distress Syndrome (ARDS)

ARDS defines a syndrome of acute respiratory failure of diverse etiology, characterized by noncardiogenic pulmonary edema, hypoxemia, and diffuse lung parenchymal consolidations.

ALI defines an early clinical stage of the same syndrome, with a milder degree of hypoxemia.

Acute onset of respiratory distress

Hypoxemia

ALI: PaO2/FiO2 ≤300 mm Hg

ARDS: PaO2/FiO2 ≤200 mm Hg

Bilateral consolidation of chest radiograph

Absence of clinical findings of cardiogenic pulmonary edema

From: American- European Consensus Conference on ARDS.