A PaO2/FiO2 ratio of less than 200 indicates which condition?

A PaO2/FiO2 ratio of less than 200 is indicative of Acute Respiratory Distress Syndrome (ARDS). This condition is characterized by a significant impairment of gas exchange due to pulmonary edema, which can be triggered by various underlying causes, such as sepsis, trauma, or pneumonia. The severity of ARDS is classified based on the degree of hypoxemia, with specific cutoffs for the PaO2/FiO2 ratio. A ratio of less than 200 indicates severe ARDS, necessitating urgent intervention and management strategies.

In contrast, while conditions like atelectasis and Acute Lung Injury (ALI) may lead to similar clinical presentations, they do not have the same strict thresholds for hypoxemia classification. Atelectasis can lead to decreased oxygenation but is typically associated with other clinical findings and factors related to lung expansion. ALI, which is a milder form of ARDS, has a higher PaO2/FiO2 cutoff (between 200 and 300). Therefore, a ratio below 200 is a clear indicator of ARDS, underscoring its significance in the assessment of acute respiratory failure.