Consensus after 1967 and 1994

ARDS is characterized by:

Acute onset

Bilateral infiltrates on chest radiograph

Pulmonary artery wedge pressure < 18 mmHg (obtained by pulmonary artery catheterization), if this information is available; if unavailable, then lack of clinical evidence of left ventricular failure suffices

if PaO2/FiO2 < 300 mmHg acute lung injury (ALI) is considered to be present

if PaO2/FiO2 < 200 mmHg acute respiratory distress syndrome (ARDS) is considered to be present