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Pulmonary vascular limitation on CPET — SCE Respiratory MCQ

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HardRespiratory PhysiologyPulmonary vascular limitation on CPETSCE Respiratory

A 57-year-old man has unexplained exertional dyspnoea. CPET shows low peak VO2, high VE/VCO2 slope, low end-tidal CO2 and preserved breathing reserve. Oxygen pulse is reduced. Spirometry is normal and TLCO is 45% predicted. What is the most likely underlying cause?

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Correct answer: E — Pulmonary vascular limitation

The best answer is “Pulmonary vascular limitation”. The clinical pattern, physiology and imaging described are most consistent with Pulmonary vascular limitation. The competing diagnoses may share individual findings, but do not account for the complete combination in the stem. The remaining choices—“Mechanical ventilatory limitation from COPD”, “Deconditioning alone, after specialist assessment”, “Upper airway obstruction”, “Obesity-related restrictive mechanics principally”—are credible in related respiratory presentations, but each addresses a different diagnostic, staging or management decision and does not fit the decisive findings and pathway position in this stem.

Reference: British Thoracic Society guideline for home oxygen: https://thorax.bmj.com/content/70/Suppl_1/i1