The Wheezing Infant: A Challenge in Evaluation and Diagnosis

Abstract

The evaluation of the wheezing infant is a common clinical problem. Initially it is important to differentiate wheezing from "noisy breathing" due to stridor. By definition, wheezing is a prolonged or continuous musical adventitial lung sound of varying intensity due to the obstruction of the intrathoracic airways. In contrast, stridor is a high-pitched, loud respiratory sound caused by oscillations of narrowed large extrathoracic airways.

Specific diagnostic criteria for asthma in infancy are not well-defined. Since wheezing is often associated with viral respiratory infections in infants, it is difficult to distinguish an initial episode of asthma triggered by a viral respiratory infection from acute viral bronchiolitis. The history is one of the most important components of the evaluation of the wheezing infant. Birth history, age of onset, history of maternal smoking, atopy, and clinical circumstances associated with the wheezing episodes may suggest a diagnosis other than asthma. Congenital anomalies or aspiration syndromes should be considered when the onset of wheezing is in the neonatal period or in young infants. Physical findings of a heart murmur, cardiac enlargement, or digital clubbing suggest underlying cardiogenic causes of wheezing. In infants with failure to thrive, underlying metabolic disorders such as cystic fibrosis should be considered.