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

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HardRespiratory emergenciesAcute exacerbation of COPD with persistent acidotic hypercapnic respiratory failureMRCEM SBA

A 69-year-old woman with established COPD presents with increased breathlessness, wheeze and purulent sputum. Chest radiography shows hyperinflation without consolidation or pneumothorax. She has received controlled oxygen, repeated nebulised bronchodilators, systemic corticosteroids and antibiotics. After 60 minutes, her SpO₂ is 90% on 28% Venturi oxygen. She remains tachypnoeic at 30/min but is alert, cooperative, haemodynamically stable and able to clear her secretions. Repeat arterial blood gas analysis shows pH 7.24, PaCO₂ 9.1 kPa and PaO₂ 8.0 kPa; her initial pH was 7.23. A monitored unit with staff experienced in non-invasive ventilation and immediate access to intubation is available. What is the most appropriate next respiratory-support plan?

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Correct answer: B — Start bilevel non-invasive ventilation in the critical-care unit.

The repeat gas demonstrates persistent acidotic hypercapnic respiratory failure despite an hour of appropriate treatment for a COPD exacerbation. Her SpO₂ is already within the recommended 88–92% range, so increasing oxygen delivery will not address the principal problem: inadequate ventilation. Bilevel non-invasive ventilation (NIV) is the treatment of choice at this point. ([nice.org.uk](https://www.nice.org.uk/guidance/ng115/chapter/Recommendations)) The pH of 7.24 makes NIV failure a substantial concern, but severe acidosis alone does not rule out a trial when intubation is immediately available. She is cooperative, can clear secretions and has no stated need for immediate airway protection. Start NIV in the monitored unit, reassess clinically and with blood gases, and establish an escalation plan. ([thorax.bmj.com](https://thorax.bmj.com/content/71/Suppl_2/ii1?utm_source=openai)) **A** may become necessary if she deteriorates or NIV fails, but intubation is not required solely because pH is below 7.25. **C** delays indicated ventilatory support despite persistent acidosis. **D** provides oxygen and some respiratory support but is not the guideline-preferred substitute for NIV in this presentation. **E** supplies continuous pressure rather than the bilevel ventilatory assistance needed to treat hypercapnia. Supplemental oxygen should remain titrated to 88–92% during NIV. ([thorax.bmj.com](https://thorax.bmj.com/content/71/Suppl_2/ii1?utm_source=openai))

Reference: NICE NG115: Chronic obstructive pulmonary disease in over 16s — recommendations 1.3.29–1.3.32 (26 July 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