The major difficulty in the diagnosis of bronchiolitis is to differentiate other diseases associated with wheezing. It may be difficult to differentiate asthma from bronchiolitis by physical examination, but age of presentation, presence of fever, and absence of personal or family history of asthma are the major differential factors. Bronchiolitis occurs primarily in the first year of life and is accompanied by fever, whereas asthma usually presents in older children with previous wheezing episodes typically unaccompanied by fever unless a respiratory tract infection is the trigger for the asthma exacerbation.
Wheezing also may be due to an airway foreign body, congenital airway obstructive lesion, cystic fibrosis, exacerbation of chronic lung disease, viral or bacterial pneumonia, and other lower respiratory tract diseases (see Chapter 78). Cardiogenic asthma, which can be confused with bronchiolitis in infants, is wheezing associated with pulmonary congestion secondary to left-sided heart failure.
Wheezing associated with gastroesophageal reflux is likely to be chronic or recurrent, and the patient may have a history of frequent emesis. Cystic fibrosis is associated with poor growth, chronic diarrhea, and a positive family history. A focal area on radiography that does not inflate or deflate suggests foreign body aspiration.
Bronchiolitis treatment consists of supportive therapy, including respiratory monitoring, control of fever, hydration, upper airway suctioning, and, if needed, oxygen administration. Indications for hospitalization include moderate to marked respiratory distress, hypoxemia, apnea, inability to tolerate oral feeding, and lack of appropriate care available at home. Hospitalization of high-risk children with bronchiolitis should be considered. Among hospitalized infants, supplemental oxygen by nasal cannula is often necessary, but intubation and ventilatory assistance for respiratory failure or apnea are required in fewer than 10% of these infants. Bronchodilators and corticosteroids are seldom effective and are not generally recommended.
Most hospitalized children show marked improvement in 2 to 5 days with supportive treatment alone. The course of the wheezing phase varies, however. Tachypnea and hypoxia may progress to respiratory failure requiring assisted ventilation. Apnea is a major concern for very young infants with bronchiolitis.
Most cases of bronchiolitis resolve completely, although minor abnormalities of pulmonary function and bronchial hyperreactivity may persist for several years. Recurrence is common but tends to be mild and should be assessed and treated similarly to the first episode. The incidence of asthma seems to be higher for children hospitalized for bronchiolitis as infants, but it is unclear whether this is causal or whether children prone to asthma are more likely to be hospitalized with bronchiolitis. There is a 1% to 2% mortality rate, highest among infants with preexisting cardiopulmonary or immunologic impairment.
Monthly injections of palivizumab, an RSV-specific monoclonal antibody, initiated just before the onset of the RSV season confers some protection from severe RSV disease. Palivizumab is indicated for some infants under 2 years old with chronic lung disease, very low birth weight, and those with hemodynamically significant cyanotic and acyanotic congenital heart disease. Immunization with influenza vaccine is recommended for all children older than 6 months and may prevent influenza-associated disease.