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Acute exacerbation of COPD with acidotic hypercapnic respiratory failure — MRCEM SBA MCQ

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HardResuscitation and critical illnessAcute exacerbation of COPD with acidotic hypercapnic respiratory failureMRCEM SBA

A 69-year-old man with established COPD presents with increased breathlessness and purulent sputum. On arrival, an arterial blood gas shows pH 7.31 and PaCO₂ 8.1 kPa. He receives controlled oxygen, air-driven nebulised salbutamol and ipratropium, systemic corticosteroids and antibiotics. After 60 minutes, his SpO₂ is 90% on 28% oxygen, respiratory rate is 30/min, and a repeat arterial blood gas shows pH 7.29 and PaCO₂ 8.4 kPa. He is alert, cooperative, haemodynamically stable and able to clear his secretions. Which management plan is most appropriate now?

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Correct answer: E — Start bilevel NIV with oxygen titrated to SpO₂ 88–92% in a dedicated unit.

The repeat gas shows worsening **respiratory acidosis with hypercapnia** despite 60 minutes of appropriate treatment. His SpO₂ is already within the recommended 88–92% range; achieving a higher saturation would not correct the ventilatory failure. Persistent pH below 7.35 and PaCO₂ above 6.5 kPa after optimal medical therapy support starting non-invasive ventilation (NIV). ([nice.org.uk](https://www.nice.org.uk/guidance/ng115/chapter/Recommendations)) **E** provides ventilatory support while retaining controlled oxygen. NIV should be delivered by experienced staff in a dedicated setting, with repeat clinical and blood-gas assessment and an agreed plan if he deteriorates. ([nice.org.uk](https://www.nice.org.uk/guidance/ng115/chapter/Recommendations)) **A** risks excessive oxygen in a hypercapnic, acidotic patient. **B** preserves the correct oxygen target but leaves the worsening ventilatory failure untreated. **C** offers CPAP rather than bilevel ventilatory support for this COPD exacerbation. **D** is premature while he remains alert, cooperative and able to protect his airway; invasive ventilation may become necessary if NIV fails or his condition deteriorates. ([thorax.bmj.com](https://thorax.bmj.com/content/71/Suppl_2/ii1?utm_source=openai))

Reference: Chronic obstructive pulmonary disease in over 16s: diagnosis and management, recommendations 1.3.25–1.3.34 (Updated 2019) — https://www.nice.org.uk/guidance/ng115/chapter/Recommendations BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults (2016) — https://thorax.bmj.com/content/71/Suppl_2/ii1 BTS guideline for oxygen use in adults in healthcare and emergency settings (2017) — https://thorax.bmj.com/content/72/Suppl_1/ii1