Question category: Respiratory
A 45 year old gentleman who has COPD presents with shortness of breath and pleuritic chest pain. He has a cough and has had several episodes of haemoptysis. He has recently returned from visiting his family in Australia. On examination he is pyrexial, tachypnoeic with saturations of 90% and there is widespread wheeze throughout his chest. Bloods reveal an elevated CRP and WCC. A CXR reveals hyperinflation of the lungs and an ECG sinus tachycardia. Which investigation should be organised to confirm the diagnosis?