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Obstructive Spirometry (COPD) — RACP Adult Medicine MCQ

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EasyRespiratoryObstructive Spirometry (COPD)RACP Adult Medicine

A 55-year-old man with a 30-pack-year smoking history presents with progressive dyspnoea. Spirometry: FEV₁ 42% predicted, FVC 78% predicted, FEV₁/FVC 0.45. Post-bronchodilator FEV₁ improves by 80 mL (4%). DLCO 55% predicted. What is the spirometry pattern?

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Correct answer: C — Obstructive pattern

FEV₁/FVC ratio <0.70 (0.45) with reduced FEV₁ and relatively preserved FVC indicates airflow obstruction. Minimal bronchodilator response (<200 mL and <12%) supports COPD rather than asthma. GOLD classification: FEV₁ 42% = GOLD 3 (severe). The reduced DLCO suggests emphysema. Alpha-1 antitrypsin testing should be performed if age <45 or strong family history.

Reference: COPD-X Australian/NZ Guidelines 2024; GOLD 2025