Patients with CPO classically present to the ED in ‘extremis’, often in the early morning.  The history is often limited initially and CPO can prove to be a difficult diagnosis to make, as it frequently occurs in patients with coexisting COPD and those at risk of pneumonia or pulmonary embolism.

Rapidly establishing the diagnosis and identifying any precipitating causes will allow instigation of appropriate treatment, alleviation of the patient’s distressing symptoms and improvement in their outcome.