A 65-year-old man with known COPD presents with increased shortness of breath, increased sputum volume, and sputum purulence for the past 2 days. He normally uses a salbutamol inhaler as needed and a tiotropium inhaler daily. His oxygen saturation is 89% on air. His FEV1 is 45% predicted. He has had two similar exacerbations in the past year requiring antibiotics. What is the most appropriate immediate management in primary care?