Which clinical scenario is most consistent with a pleural effusion showing a pleural fluid protein to serum protein ratio of 0.3?

A pleural fluid protein to serum protein ratio of 0.3 indicates that the fluid is transudative rather than exudative. Transudative pleural effusions typically arise from conditions that alter the balance of hydrostatic and oncotic pressures rather than from inflammatory or infectious processes.

In the scenario of a 70-year-old man with an ejection fraction of 30%, heart failure is likely contributing to the development of the pleural effusion. In heart failure, increased hydrostatic pressure in the pulmonary capillaries leads to fluid accumulation in the pleural space, which reflects in the pleural fluid characteristics consistent with a transudative process.

In contrast, the other options present clinical scenarios more consistent with exudative pleural effusions. The 32-year-old man with HIV who is experiencing fever and cough could potentially be dealing with an infectious process, such as pneumonia or tuberculosis, which often leads to exudative pleural effusions. The 45-year-old woman with a tracheostomy and the 65-year-old man with newly diagnosed lung cancer may have other underlying conditions that could also cause exudative effusions due to malignancy or localized infection/inflammation.

Thus, the pleural fluid protein to serum