ARDS true?
ARDS is a clinical syndrome of severe dyspnoea of rapid onset, hypoxaemia and diffuse pulmonary infiltrates leading to respiratory failure.ARDS is characterised by Po2/Fio2(inspiratory O2 fraction)<200 mmHg.There will be no hypercapnia, so the patient will have type 1 respiratory failure. 
There will be a stiff-lung syndrome with collapse and decreased compliance of the lungs due to loss of surfactant.
Type 2 respiratory failure
Lung compliance decreased
Increase in diffusion capacity
none