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COPD exacerbation with acute hypercapnic respiratory failure — SCE Acute Medicine MCQ

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HardAcute Respiratory PresentationsCOPD exacerbation with acute hypercapnic respiratory failureSCE Acute Medicine

A 72-year-old woman with severe COPD presents with drowsiness and increased sputum. She is receiving 15 L/min oxygen via non-rebreathe mask. ABG shows pH 7.25, PaCO2 9.8 kPa, PaO2 18.5 kPa, bicarbonate 31 mmol/L and lactate 1.2 mmol/L. Chest radiograph shows hyperinflation without consolidation. What is the most appropriate next step in management?

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Correct answer: C — Controlled oxygen targeting 88-92% and start acute NIV

The ABG shows acute-on-chronic hypercapnic respiratory failure due to COPD, worsened by excessive oxygen, so controlled oxygen and bilevel NIV are indicated. Continuing high-flow oxygen can worsen CO2 retention through V/Q mismatch and the Haldane effect. Sodium bicarbonate does not treat ventilatory failure. The pearl is that NIV should be started promptly when pH is below 7.35 with hypercapnia after initial medical therapy, provided there is no immediate need for intubation.

Reference: BTS/ICS Guideline for acute hypercapnic respiratory failure