COPD USMLE Step 1 Practice Question
A 34-year-old woman presents with sudden pleuritic chest pain and dyspnea 5 days post-cesarean delivery. Vital signs show HR 110 bpm, RR 24/min, BP 128/82 mmHg, SpO2 88% on room air. Arterial blood gas reveals pH 7.48, PaCO2 32 mmHg, PaO2 62 mmHg. CT pulmonary angiography demonstrates segmental pulmonary artery filling defect. She denies recent leg swelling. Which pathophysiologic change is most likely present in the affected lung regions?
Answer choices
- ADecreased ventilation and decreased perfusion
- BDecreased ventilation and normal perfusion
- CIncreased perfusion and decreased dead space
- DNormal ventilation and decreased perfusionCorrect answer
- EIncreased diffusion capacity due to capillary recruitment
- FPulmonary infarction causing alveolar consolidation
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.