Asthma USMLE Step 1 Practice Question

A 7-year-old boy with no prior respiratory disease presents to the emergency department with acute onset dyspnea and bilateral wheezing that began 10 minutes after sprinting during a soccer game on a cold, dry day. He denies fever, cough, or recent upper respiratory infection. Physical examination reveals clear bilateral wheezing, prolonged expiratory phase, and peak expiratory flow of 62% predicted. Oxygen saturation is 94% on room air. He receives nebulized albuterol and shows rapid clinical improvement with normalization of peak flow to 88% predicted within 30 minutes. Which of the following is the most likely diagnosis?