A 19-year-old female patient presents with wheezing and shortness of breath. She has a history of moderate asthma but has generally been able to control symptoms through Step 3 maintenance therapy and reports adherence to a low-dose inhaled corticosteroid (ICS), formoterol. She also reports that she has begun using e-cigarettes. On presentation, the patient has assumed a sitting position. Pulsus paradoxus is present (14 mm Hg), and the heart rate is 118 beats/min.