Evaluation of the wheezing infant.

Wheezing is a very common symptom or sign in the infant. The evaluation of the underlying cause of the wheezing is difficult and requires a thorough assessment of several factors in the history and physical examination and a basic understanding of the pathophysiology of wheezing. With the increased availability of infant pulmonary function equipment, the evaluation of serial pulmonary function studies in infants with wheezing should prove helpful in continued assessment of the reversibility of their airway obstruction using bronchodilators and the effect of antiinflammatory pharmacologic agents on long-term hyperresponsiveness of the airways. Wheezing-associated respiratory tract infections in infancy ("wheezy bronchitis") and asthma share common risk factors, including history of exposure to environmental tobacco smoke, but the link between these two entities is still controversial. Each infant who presents with wheezing should be assessed individually with a thorough history and physical examination and an evaluation of the likelihood of asthma versus other underlying causes of wheezing such as cystic fibrosis, aspiration syndromes, congenital anomalies, or environmental factors such as exposure to passive tobacco smoking.