Management of exercise-induced bronchospasm in children.

Bronchospasm precipitated by exercise is often indistinguishable from bronchospasm produced by other stimuli. Symptoms result from airflow limitation and include wheezing, cough, chest tightness, dyspnea and sometimes hypoxemia. The prevalence of exercise-induced bronchospasm varies from 30%-90%, but virtually all patients with current asthma will experience a decrease in lung function if the exercise is sufficiently vigorous, especially in cold, dry environmental conditions. Exercise-induced bronchospasm is more prevalent in children than in adults, probably because children are physically more active. It is also more prevalent among elite winter sports athletes. The pathogenesis of exercise-induced bronchospasm involves a defect in respiratory heat exchange that probably triggers mast cell and eosinophil release of bronchoconstricting mediators. The goal of therapy is prevention of symptoms. This may be accomplished by pre-treating patients with isolated exercise-induced bronchospasm using an inhaled rapid-onset β2-adrenergic agonist before a scheduled activity or by treating the underlying inflammation when exercise-induced bronchospasm is part of the clinical syndrome of persistent asthma. In the later instance, either an inhaled corticosteroid, an oral leukotriene modifier, or a combination of both, depending on severity, may be required to prevent exercise-induced bronchospasm associated with activities of daily living. In addition, some of these patients may still require pre-treatment with a short-acting inhaled β2-agonist before a scheduled vigorous activity, especially in very cold ambient temperatures. Because the duration of bronchoprotection decreases with daily use (tachyphylaxis), long acting β2-adrenergic agonists (e.g., formoterol, salmeterol) have a limited role in treating exercise-induced bronchospasm.