A 10-year-old girl presents to the emergency department during the winter with an acute severe asthma exacerbation — she is coughing and has dyspnea, chest tightness, and loud biphasic wheezing. She is unable to speak in complete sentences and has difficulty getting out more than a few words at a time. Physical exam shows presence of suprasternal retractions. Her respiratory rate is 40 breaths/min, heart rate is 130 beats/min, and oxygen saturation is 85%. Her body temperature is 98.6 °F (37 °C).

The patient had a history of recurrent moderate preschool wheezing and developed exercise-induced asthma at age 6 years. In addition, she has become increasingly sensitive to cold weather and experiences acute episodes of coughing, wheezing, dyspnea, and chest tightness when outdoors during the winter.

Laboratory testing found high serum immunoglobulin E levels (1300 kU/l) and positive skin prick tests to house dust mites and dog and cat dander. Despite treatment with progressively increasing doses of inhaled fluticasone (≤ 1000 μg/day) combined with salmeterol (100 μg/day) over the past 3 years, bimonthly hospital admissions with systemic steroid use were reported. After checking inhaler technique and adherence to treatment, both of which were good, comorbidities, including obesity (body mass index was within the normal range at 18.6 — height is 5 ft 5 in, weight is 80 lb), rhinosinusitis, and gastroesophageal reflux, were excluded. The patient was negative for SARS-CoV-2 and influenza A and B infections as determined by rapid polymerase chain reaction nasopharyngeal swab. Respiratory pathogens panel is negative for respiratory syncytial virus (RSV) and other pathogens.