COPD USMLE Step 1 Practice Question
A 70-year-old man with a 15-year history of COPD and systolic heart failure (EF 35%) presents with progressive dyspnea. Vital signs: BP 148/92, HR 102, RR 24, SpO2 88% on room air. Chest X-ray shows moderate bilateral pleural effusions. Thoracentesis yields clear, transudative fluid with protein 2.2 g/dL and LDH 180 IU/L. No fever or recent infection. Which mechanism best explains this effusion?
Answer choices
- AObstruction of lymphatic drainage by mesothelioma
- BLeak of pancreatic enzymes into the pleural space
- CIncreased hydrostatic pressure causing a transudateCorrect answer
- DIncreased vascular permeability causing an exudate
- ERupture of the thoracic duct causing chylothorax
- FDecreased plasma oncotic pressure from severe hepatic cirrhosis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.