Change of bronchial hyperresponsiveness in asthmatic children

Bronchial hyperresponsiveness (BHR) is a factor in predicting bronchial asthma independently of inflammation markers.

The aims were to determine the frequency and important predictive facts of BHR and the effect of prophylaxis by Global Initiative for Asthma (GINA) and National Asthma Education and Prevention Program (NAEPP) on BHR in asthmatic children.

BHR in 106 children was evaluated by the bronchoprovocation test with methacholine.

The prevalence rate of symptomatic BHR is 18% for crucial point of PC20 = 4.1 +/- 3.03 mg/ml and PD20 = 3.22 +/- 2.59 micromol methacholine. On average asthmatic children express moderate BHR, which persists even two years after administering prophylaxis. After two years bronchial reactivity is significantly smaller, the change of FEV1 is significantly smaller, the velocity of change of slope dose response curve (sDRC) is faster and the provocative concentration of methacholine that causes wheezing is 2-3 times lower. A mild sDRC shows milder bronchoconstriction after two years. The fast change of bronchial reactivity in 41% of asthmatic children is contributed to aero-pollution with sulfur dioxide and/or, possible insufficient and/or inadequate treatment during two years of administering prophylaxis. A simultaneous effect of allergens from home environment and grass and tree pollens and of excessive aero-pollution on children's airways is important in the onset of symptomatic BHR. After two years of treatment by GINA and NAEPP children do not show asthma symptoms or show mild asthma symptoms, however bronchial sensitivity remains unchanged.

Optimal duration of anti-inflammatory treatment in asthmatic children who show moderate bronchial hyperresponsiveness should be longer than two years.