A 68-year-old man with a 50-pack-year smoking history presents with increased dyspnoea, sputum purulence and volume over 3 days. He has known COPD with FEV1 45% predicted. On examination, he is febrile (38.1 °C), RR 24 breaths/min, SpO2 90% on room air and has bilateral expiratory wheeze. Chest X-ray shows no consolidation. Which management option is most appropriate for this COPD exacerbation in the community?