A PaO2/FiO2 ratio of less than or equal to 200 mm Hg is indicative of which condition?

A PaO2/FiO2 ratio of less than or equal to 200 mm Hg is indicative of acute respiratory distress syndrome (ARDS). This condition is characterized by severe inflammation and increased permeability of the alveolar-capillary membrane, leading to significant hypoxemia. In ARDS, the ability of oxygen to diffuse into the bloodstream is impaired, resulting in lower PaO2 values relative to the fraction of inspired oxygen (FiO2).

The specific cutoff of a 200 mm Hg ratio is part of the Berlin definition of ARDS, which classifies it into mild, moderate, and severe categories based on the degree of hypoxemia. Understanding the PaO2/FiO2 ratio is crucial in assessing the severity of respiratory failure and guiding management in patients with ARDS.

Other conditions, such as heart failure, pneumonia, and chronic obstructive pulmonary disease (COPD), may also affect oxygenation but do not specifically correlate to this particular level of the PaO2/FiO2 ratio as a defining criterion for ARDS. Each of these conditions presents distinct diagnostic criteria and management strategies, making the interpretation of the PaO2/FiO2 ratio specifically relevant for recognizing and treating ARDS.