A 62-year-old man comes to the emergency department due to a 2-week history of worsening shortness of breath. The patient reports feeling dyspneic while lying flat and has been sleeping upright in his recliner. Temperature is 36.7 C (98.1 F) , blood pressure is 110/70 mm Hg, pulse is 88/min, and respirations are 20/min. On physical examination, jugular venous distension is present. Heart sounds are normal. Decreased breath sounds and dullness to percussion can be heard at the bilateral bases. Pitting edema is present in the bilateral lower extremities. Chest x-ray shows cardiomegaly and bilateral pleural effusions. Serum protein is 6 g/dL and serum lactate dehydrogenase (LDH) is 60 U/L. Which of the following sets of pleural fluid findings is most likely to be seen in this patient?

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11ec160b_3b42_12c4_9249_1d9b5cc0a589_MD0001_00 This patient with dyspnea, orthopnea, jugular venous distension, and lower extremity swelling likely has an acute heart failure exacerbation. Heart failure commonly leads to pleural effusion due to poor forward blood flow from the left ventricle and a subsequent increase in pulmonary venous and pulmonary capillary hydrostatic pressure. Pleural effusions that result from such pressure changes are typically transudative, whereas those that result from an inflammatory increase in vascular membrane permeability are typically exudative. Because transudative and exudative pleural effusions have differing underlying causes, they also tend to differ in chemical makeup. The Light criteria are used to differentiate the 2 types via analysis of the total protein and lactate dehydrogenase (LDH) levels. Exudative effusions have a high pleural fluid/serum ratio of these proteins due to increased capillary permeability, while transudative effusions are associated with a low pleural fluid/serum ratio. Glucose levels and leukocyte counts can suggest the degree of inflammation in a pleural effusion. Because leukocytes metabolize glucose, highly inflammatory effusions typically have low glucose levels. Transudative effusions are not inflammatory and almost always have low nucleated cell counts and normal (or high) glucose levels. (Choices B and D) These effusions meet Light criteria for an exudate. The low glucose levels (<60 mg/dL) suggest consumption of glucose by an abundance of metabolically active cells, as can occur with highly inflammatory exudative effusions resulting from bacterial infection, malignancy, or rheumatologic disease. (Choices C and E) These effusions meet Light criteria for an exudate. The normal glucose levels and low cell counts suggest a relatively low-inflammation exudative effusion such as an uncomplicated parapneumonic effusion or effusion due to pulmonary embolism. Educational objective: Transudative pleural effusions result from increased intracapillary pressure (eg, heart failure) and exudative effusions develop from inflammatory disruption of the vascular membrane. Transudative pleural effusions have low fluid/serum ratios of total protein and lactate dehydrogenase and low absolute levels of lactate dehydrogenase compared to exudative effusions.

A 62-Year-Old Man Comes to the Emergency Department Due to a 2-Week