pediatrics
Bronchiolitis
Diagnosis of Bronchiolitis
Clinical evaluation Pulse oximetry Chest x-ray for more severe cases Respiratory syncytial virus (RSV) antigen test on nasal washings, nasal aspirates, or nasal swabs for seriously ill children Diagnosis of bronchiolitis is suspected by history, examination, and occurrence of the illness as part of an epidemic. Symptoms similar to bronchiolitis can result from an Wheezing and Asthma in Infants and Young Children exacerbation, which is often precipitated by a respiratory viral infection and is more likely in a child > 18 months of age, especially if previous episodes of wheezing and a family history of asthma have been documented. Gastric reflux with aspiration of gastric contents also may cause the clinical picture of bronchiolitis; multiple episodes in an infant may be clues to this diagnosis. Foreign body aspiration occasionally causes wheezing and should be considered if the onset is sudden and not associated with manifestations of upper respiratory infection. Heart failure associated with a left-to-right shunt manifesting at age 2 to 3 months also can be confused with bronchiolitis. Patients suspected of having bronchiolitis should undergo pulse oximetry to evaluate oxygenation. No further testing is required for mild cases with normal oxygen levels, but in cases of hypoxemia and severe respiratory distress, a chest x-ray supports the diagnosis and typically shows hyperinflated lungs, depressed diaphragm, and prominent hilar markings. Infiltrates resulting from atelectasis and/or RSV pneumonia may be present; RSV pneumonia is relatively common among infants with RSV bronchiolitis. RSV rapid antigen testing done on nasal washings, nasal aspirates, or nasal swabs is diagnostic but not generally necessary; it may be reserved for patients with illness severe enough to require hospitalization because it may guide isolation and bed assignment decisions. Other laboratory testing is nonspecific and is not routinely indicated; about two thirds of the children have white blood cell counts of 10,000 to 15,000/mcL (10 to 15 × 109/L). Most have 50 to 75% lymphocytes. 