<prompt> Which of the following is not seen in ARDSPulmonary edemaHypoxemiaStiff lungHypercapnia  <response>: 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 alveolarpulmonary 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:Harrisons medicine-18th edition,page no:2205-2207,Textbook of pathology-Harsh Mohan,6th edition,page no:463 