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NIV Failure in COPD — FRCA Final MCQ

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ModerateIntensive Care MedicineNIV Failure in COPDFRCA Final

A 70-year-old man is admitted to the ICU with acute hypercapnic respiratory failure due to an exacerbation of COPD. After optimal medical therapy, his arterial blood gas before starting non-invasive ventilation shows pH 7.28 and PaCO2 9.5 kPa. Over the next 2 hours, mask leak and patient–ventilator asynchrony are corrected, and bilevel NIV is progressively increased to IPAP 22 cmH2O and EPAP 6 cmH2O. Despite this, his respiratory rate remains 36 breaths/min, his pH falls to 7.20, his PaCO2 rises to 11.2 kPa, and his GCS falls from 15 to 10. He has no agreed limitation of treatment. What is the most appropriate next step?

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Correct answer: C — Perform tracheal intubation and commence invasive mechanical ventilation

The correct answer is C. His pH has fallen from 7.28 to 7.20 and PaCO2 has risen despite correction of mask leak and asynchrony and escalation of pressure support. This is deteriorating respiratory acidosis despite optimised NIV, for which BTS/ICS guidance recommends considering invasive mechanical ventilation. The falling GCS and persistent tachypnoea reinforce the urgency, although GCS 10 alone is not an absolute guideline threshold. Further pressure escalation risks delaying necessary intubation. CPAP provides no inspiratory pressure support and is unsuitable for worsening hypercapnic ventilatory failure. Bronchodilator therapy should continue but is not an adequate sole response. High-flow nasal oxygen does not provide equivalent ventilatory support and should not replace failed NIV in severe acidotic hypercapnic respiratory failure.

Reference: Davidson AC et al. BTS/ICS Guideline for the ventilatory management of acute hypercapnic respiratory failure in adults (Thorax 2016; BMJ Open Respiratory Research reprint), section on NIV failure and indications for invasive ventilation. 2016. https://pubmed.ncbi.nlm.nih.gov/26976648/