A 41-year-old woman with known asthma presents to the Emergency Department with rapidly worsening breathlessness. Her oxygen saturation is 90% on air and rises to 96% with supplemental oxygen. She is unable to complete full sentences, appears exhausted, and is intermittently confused. She has already received repeated oxygen-driven nebulised salbutamol with ipratropium and intravenous hydrocortisone. What is the most appropriate next step in management?
