Acute Severe Asthma in a 24-Year-Old Woman

Patient B-217, a 24-year-old woman, presents to the emergency department with an acute exacerbation of asthma. She has had asthma since childhood and is usually controlled on inhaled beclometasone and salbutamol. Over the past 24 hours, she has experienced increasing wheeze and breathlessness, unresponsive to her salbutamol inhaler. On arrival, she is sitting upright, leaning forward, and is able to say only single words. On examination: respiratory rate 36/min, heart rate 130/min, blood pressure 128/82 mmHg, oxygen saturation 88% on room air, temperature 36.8°C. Peak expiratory flow is 180 L/min (predicted 400 L/min). The chest is hyperinflated with widespread expiratory wheeze. She has no known drug allergies. Current medicines: salbutamol inhaler as required, beclometasone inhaler 200 micrograms twice daily. She was recently prescribed propranolol for migraine prophylaxis, but has not yet taken it. She is not pregnant. Renal function is normal (serum creatinine 0.8 mg/dL, eGFR 105 mL/min/1.73m2). Write the immediate prescriptions for this patient, including oxygen therapy, nebulised bronchodilators, and a systemic corticosteroid. Also identify any drugs that should be avoided in this patient.