MRCP2-4530

MRCP2-4530

An 85-year-old man presents to the hospital with an infective exacerbation of COPD. He complains of increasing shortness of breath, dry cough, and an episode of rigors. Despite being started on salbutamol and ipratropium nebulisers and steroids, he fails to improve clinically. Non-invasive ventilation is offered and he tolerates it well, but 36 hours later, he starts to become more breathless. On examination, he has crackles and wheeze on the right hemithorax, and the left hemithorax has reduced air entry throughout. There are no added sounds, no JVP or leg oedema that can be seen, but there is accessory muscle use. He is tired and feels ‘absolutely awful’. The non-invasive ventilation is currently set at IPAP 26 cm H2O and EPAP 6 cm H2O. A repeat chest x-ray is pending.

What is the likely cause of this deterioration?