A 28 year old man presents with severe dyspnea and wheezing for 1 day. He was diagnosed with mild persistent bronchial asthma in childhood, and is currently on a salbutamol inhaler. He also experienced a mild productive cough, rhinorrhea and a sore throat during the preceding week. He does not smoke and has no other comorbidities or allergies.
WBC: 8,000/mm3 N: 70%, L: 28% Hb: 14 g/dl Plt: 300,000/mm3
PEFR: 180 L/min (40% of predicted) FEV1: 1.5 L (37% of predicted)
On room air: pH: 7.5 PaCO2: 30 mmHg PaO2: 60 mmHg
The x-ray appears normal.