Any aspect of the history that is atypical for asthma, such as a history of sudden onset of symptoms, coughing or wheezing with feedings, neonatal requirement for ventilatory support, or symptoms of stridor, may suggest the need to consider alternative diagnoses. A large number of conditions can result in symptoms suggestive of asthma. The most common nonasthmatic conditions in childhood that involve obstruction of the large airways include foreign body in the trachea, bronchus or esophagus, and laryngotracheomalacia. Obstruction involving both the large and small airways are most commonly due to viral bronchiolitis and cystic fibrosis. The differential diagnosis of the child with wheezing can be approached on an age-related basis.
Infants are at a higher risk for congenital abnormalities and some infectious conditions.
Aspiration of a foreign body and cystic fibrosis may occur in any age group, but most commonly present early in life. GER with pulmonary involvement may occur at any age. Vocal cord dysfunction and the hyperventilation syndrome merit consideration mainly in the adolescent age group. Objective measurement of pulmonary function is important whenever possible not only to confirm the clinical diagnosis but to monitor asthma as well. Expiratory spirometry should be used as soon as the child is old enough to cooperate.