A 59-year-old man with known COPD (FEV1 45% predicted) presents with increased breathlessness, increased sputum volume, and sputum purulence over the past 3 days. He normally uses Tiotropium and Salmeterol/Fluticasone inhalers. His oxygen saturation is 90% on air, RR 24/min, Temp 37.8°C. Chest auscultation reveals scattered wheezes and crackles. According to NICE guidelines, which management step is indicated in addition to optimising bronchodilators and considering oxygen?