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COPD with post-exacerbation persistent hypercapnia — SCE Respiratory MCQ

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HardDischarge PlanningCOPD with post-exacerbation persistent hypercapniaSCE Respiratory

A 69-year-old man with severe COPD is preparing for discharge after an exacerbation causing acute-on-chronic hypercapnic respiratory failure. Admission arterial blood gas analysis showed pH 7.20 and PaCO2 10.8 kPa, and he required acute non-invasive ventilation. He is established on long-term oxygen therapy for previously confirmed stable hypoxaemia. Forty-eight hours after stopping ventilatory support, he has returned to his usual functional state. Arterial blood gas analysis on his prescribed oxygen shows pH 7.38, PaCO2 7.4 kPa and PaO2 8.2 kPa. His BMI is 24 kg/m², and there are no clinical features of obstructive sleep apnoea, neuromuscular disease or chest-wall disease. His maintenance treatment, inhaler technique, pulmonary rehabilitation referral and self-management plan have been addressed. Which respiratory-support plan is most appropriate?

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Correct answer: A — Continue long-term oxygen therapy and reassess in a specialist ventilation service at 2–4 weeks, initiating CO2-targeted home non-invasive ventilation if hypercapnia persists

This patient should be referred for specialist consideration of long-term home NIV because he has chronic hypercapnic respiratory failure and has required assisted ventilation during a COPD exacerbation. However, hypercapnia measured immediately after acute NIV may resolve spontaneously during recovery. Starting home NIV during the admission or reassessing within 72 hours risks treating transient post-exacerbation hypercapnia. This distinction probably explains why early enrolment in the RESCUE trial was neutral, whereas HOT-HMV selected patients with PaCO2 above 7.0 kPa persisting 2–4 weeks after resolution of respiratory acidaemia and demonstrated prolonged time to readmission or death. If hypercapnia persists, NIV should be titrated to achieve a substantial PaCO2 reduction. A is premature despite the apparently compensated chronic hypercapnia. B remains too early to establish persistence. D confuses the recommended post-exacerbation NIV reassessment window with the longer period of stability commonly used for formal LTOT assessment; his established LTOT should continue, but ventilation review should not be delayed to 8 weeks. E imposes an unnecessary further life-threatening event: the current episode already meets the criterion for specialist referral. The absence of obesity, sleep-apnoea features, neuromuscular disease and chest-wall disease makes the evidence for COPD-associated persistent hypercapnia directly applicable.

Reference: Chronic obstructive pulmonary disease in over 16s: diagnosis and management (Updated 2019) — https://www.nice.org.uk/guidance/ng115/chapter/Recommendations European Respiratory Society guidelines on long-term home non-invasive ventilation for management of COPD (2019) — https://publications.ersnet.org/content/erj/early/2019/08/21/1399300301003-2019.full Effect of Home Noninvasive Ventilation With Oxygen Therapy vs Oxygen Therapy Alone After an Acute COPD Exacerbation (2017) — https://pubmed.ncbi.nlm.nih.gov/28528348/