George Davies is a retired 70-year-old man who lives in retirement flat. He has been referred to the Acute Medical Unit (AMU) by his GP with increasing shortness of breath, reduced exercise tolerance and an increasingly productive cough. George has a long history of chronic obstructive pulmonary disease (COPD) and often gets admitted in the winter months. Until retirement he had smoked 40 cigarettes a day for most of his adult life and still smokes 20 cigarettes a day. On admission you can see that George is in obvious respiratory distress. He is using his accessory muscles and is unable to complete sentences. He is centrally cyanosed and has pursed lips on expiration and you can hear rattling in his chest. His skin is warm and mucous membranes are dry. He is very drowsy and appears confused. George is 1.7 m tall and weighs 56 kg.