A 70-year-old man is admitted with an acute exacerbation of COPD, presenting with increased breathlessness, wheeze, and increased sputum purulence. His oxygen saturation is 89% on air. Initial management includes controlled oxygen therapy (aiming for sats 88-92%), nebulised Salbutamol and Ipratropium, and oral Prednisolone 30mg. According to NICE guidelines, what other treatment should be routinely considered?