A 70-year-old man with COPD presents with increased dyspnoea, purulent sputum and wheeze. Oxygen saturation is 86 percent on air. What is the most appropriate initial oxygen strategy?AGive controlled oxygen via Venturi mask to target saturations of 88–92 percentBGive high-flow oxygen to achieve saturations of 100 percentCAvoid oxygen therapy to prevent carbon dioxide retentionDGive home oxygen concentrator and dischargeEStart non-invasive ventilation without oxygenCheck my answer