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Controlled Oxygen in COPD — RACP Adult Medicine MCQ

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EasyRespiratoryControlled Oxygen in COPDRACP Adult Medicine

A 70-year-old man with COPD presents with acute exacerbation. SpO₂ is 85% on room air. He is alert and not in extremis. PaCO₂ on initial ABG is 55 mmHg. He is a known CO₂ retainer. What is the most appropriate oxygen delivery device?

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Correct answer: D — Venturi mask 28% (4 L/min)

In COPD patients at risk of hypercapnic respiratory failure, controlled oxygen therapy via Venturi mask (28% initially, titrated to target SpO₂ 88-92%) is appropriate. The Venturi mask delivers a fixed FiO₂ regardless of respiratory pattern. Avoid high-flow uncontrolled oxygen (non-rebreather) as it may worsen CO₂ retention via the Haldane effect and reduced hypoxic drive.

Reference: COPD-X Australian/NZ 2024; BTS 2024 Oxygen Guidelines