Your 6-month-old patient presents with expiratory wheezing, tachypnea, and crackles. You suspect bronchiolitis because?

The suspicion of bronchiolitis in a 6-month-old patient presenting with expiratory wheezing, tachypnea, and crackles is primarily supported by the understanding that asthma is rare in children under one year of age. Bronchiolitis is commonly caused by viral infections, particularly the respiratory syncytial virus (RSV), and it typically affects infants and toddlers, especially those less than 24 months old.

In infants as young as six months, the airway structure and the immune response are still developing, which makes them more susceptible to infections that lead to conditions like bronchiolitis, rather than chronic diseases like asthma, which usually manifest later in childhood. As a result, the clinical picture presented—wheezing, crackles, and tachypnea—aligns more closely with bronchiolitis in this age group.

While other factors such as seasonal trends can play a role in the prevalence of bronchiolitis, the rare occurrence of asthma in infants less than one year old is a key diagnostic consideration. Therefore, the patient's age and the typical presentation of bronchiolitis in this demographic contribute strongly to the suspicion of bronchiolitis over other respiratory conditions.