Which of the following is not seen in ARDS

Acute respiratory distress syndrome is a clinical syndrome of severe dyspnoea of rapid onset,hypoxaemia,and diffuse pulmonary infiltrates leading to respiratory failure.It is also known as hyaline membrane disease.The exudative phase is characterised by alveolar/pulmonary edema predominantely involving dependent poions of the lung,leading to diminished aeration,hypoxaemia,& atelectasis.As a result ofncoating of the alveoli with hyaline membranes,there is loss of surfactant causing collapse called 'stiff lung'. ARDS is characterized by type 1 respiratory failure which has only hypoxia but the value of CO2 is normal. ARDS has noncardiogenic pulmonary edema with normal PCWP. Reference:Harrison's medicine-18th edition,page no:2205-2207,Textbook of pathology-Harsh Mohan,6th edition,page no:463