Childhood asthma: overview.

Abstract

DEFINITION Asthma is a syndrome characterized by increased responsiveness of the trachea and bronchi to various stimuli and is manifested by widespread reversible narrowing of the airways that changes in severity either spontaneously or as a result of therapy.1 The hyperresponsiveness (twitchiness) of airways is a fundamental abnormality and is dynamic in nature. Asthma is a disease of persistent or airway inflammation characterized by the presence of inflammatory cells (eosinophils and polymorphonuclear cells), edema of the wall, and changes in epithelial cells. Airway response to allergens and certain irritants may be acute (occurring within minutes to one hour following exposure), delayed or late (occurring within four to eight hours following exposure), or dual (combination of acute and late phase). Some reactions are only delayed. The late phase reaction is largely attributed to ongoing inflammation. Because of the variability of its presentation (complete v partial reversibility of airways obstruction, hyperreactivity accompanying other respiratory disease, chronic cough, or pneumonia with or without wheeze), children have often been denied appropriate antiasthmatic medications and their symptoms have been attributed instead to wheezy bronchitis, recurrent bronchiolitis, spastic bronchitis, or wheezy baby syndrome. For years pediatricians have been schooled to approach the wheezing child skeptically (all that wheezes is not asthma).