Q: Acute respiratory distress syndrome (ARDS) is diagnostic

A) If P/F ratio less than 200
B) If Pulmonary Wedge Pressure less than 18
C) if bilateral infiltrates present with negative sputum culture
D) is diagnosis of exclusion
E) if improvement in P/F ratio by prone positioning



Answer:  D

Though seems very basic but it is of utmost importance to understand that ARDS is a diagnosis of exclusion. This is the basis of new Berlin definition of ARDS. All other causes of hypoxemia need to be ruled out, with objective evaluation including floatation of  Pulmonary Artery Catheter (swan), echocardiography, bronchoscopy, and/or lung biopsy.