Pulmonary Embolism USMLE Step 1 Practice Question
A 71-year-old man with COPD and cor pulmonale presents with acute dyspnea and syncope. Chest X-ray shows cardiomegaly and pulmonary congestion. Arterial blood gas reveals PaO2 55 mmHg, PaCO2 65 mmHg on 2L oxygen. D-dimer is markedly elevated. Which of the following is the most accurate statement regarding PE diagnosis in this patient?
Answer choices
- ASyncope in COPD patients always indicates cor pulmonale decompensation
- BElevated D-dimer excludes PE and suggests acute COPD exacerbation
- CClinical suspicion for PE is high despite overlapping respiratory disease; CTPA is indicatedCorrect answer
- DHypercapnia excludes PE as a diagnosis
- EHigh pretest probability rules out need for confirmatory imaging
- FNormal D-dimer would have effectively ruled out PE, making CTPA unnecessary in this clinical scenario
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