Abstract: The current diagnostic criteria of ARDS is based on the Berlin definition, chest radiography, oxygenation index and other parameters are used to define patients. However, there are some defects in this standard, such as the subjectivity of chest radiography interpretation, the inconformity of pathological changes and clinical symptoms, so the accuracy of the standard is questioned. Increase in pulmonary vascular permeability accompanied with accumulation of excess extravsscular lung water(EVLW)is the hallmark of ARDS. EVLW and pulmonary vascular permeability index(PVPI )can be quantitatively measured using the transpulmonary thermodilution technique, which can provide basis for accurate diagnosis and treatment of ARDS. EVLW more than 10 mL/kg is a reasonable criterion for pulmonary edema, meanwhile PVPI more than three suggests increased vascular permeability of ARDS. EVLW and PVPI measurement will provide accurate indicators for clinical practice and research of ARDS.

Key words: acute respiratory distress syndrome, pulmonary edema, pulmonary permeability, transpulmonary thermodilution