The Study Of Small Airway Function In Children Asthma

Objectives:We studied asthmatic children who were newly diagnosed and treated with ICS, lung function parameter, the airway responsiveness (AHR) were measured in order to investigate the relationship between small airway function parameter and asthma.Methods: We studied 60 asthmatic children who were newly diagnosed, then gave them inhaled corticosteroid (ICS) treatment. Lung function were measured with tradition method, the airway responsiveness(AHR) were measured by methacholine(Mch) provocation test. 60 asthmatic children were divided into 4 groups, group A (percent predicted maximal midexpiratory flow, MMEF%pre≥80%,n=25), group B (MMEF%pre<80%,n=35), group C (positive tests for Mch bronchial provocation, n=33), group D (negative tests for Mch bronchial provocation, n=25). The data (PEF%pre,FEV1%pre, FEF75%pre, FEF50%pre, FEF25%pre, sex, age, the clinical period, the duration of history of wheezing, positive rate of allergens, the allergic history, the asthma of family history, AHR) from group A and group B were compared. The data (the severity of asthma, the duration of history of wheezing) from group C and group D were compared. The data (FEF75%pre, FEF50%pre, FEF25%pre, MMEF%pre, AHR ) from 18 asthmatic children after ICS treatment were compared with before that.Result: 1.In the 60 asthmatic children, the small airway function parameter correlated significantly with Mch provocation test(P<0.05);FEF50%Pre and MMEF%Pre correlated significantly with the duration of history of wheezing(P<0.05).2. Asthmatic children of group B were severer(P<0.05), more in period of exacerbation(P<0.01) than that of group A. There was no significant diference of the date(sex, age, positive rate of allergens, the allergic history, the asthma family history) between group A and group B(P>0.1)。3. There was no significant diference of the data(the duration of history of wheezing, the severity of asthma) between group C and group D(P>0.1).4. There was no significant diference of FEF75%pre, FEF50%pre, FEF25%pre, MMEF%pre in 11 asthmatic children between after ICS treatmen(t≥12 months)and before ICS treatment (P>0.05). FEF75%pre, FEF50%pre and MMEF%pre in asthmatic children after ICS treatment (<12 months) were higher than that before (P<0.05), but they were less than 80%pre. 5. The small airway function parameter (FEF50%pre, FEF25%pre, MMEF%pre) did not correlate with duration of ICS treatment(P>0.1). There was no correlation between with FEF75% and duration of ICS treatment(P=0.025,r=0.526). 6. 8 subjects with negative dosimeter were in period of exacerbation and they were mild asthma.Conclusion: 1. Some of asthmatic children continued to exhibit small airway obstruction, including asthmatic symptoms well controlled after ICS treatment. 2. There was no significant diference between asthmatic children whose small airway function was normal and abnormal in sex, age, positive rate of allergens, the allergic history, the asthmatic history of family. The small airway dysfunction was often accompanied by large airway function dysfunction which was more serious than patients whose small airway function is normal in asthmatic children. Percent predicted maximal midexpiratory flow (MMEF%pre) may be a sensitive marker for detecting the attacks and severity of asthma in asthmatic children. 3. There were significant negative correlations between the small airway function parameter included FEF50%pre, FEF75%pre, FEF25%pre, MMEF%pre and the Mch bronchial provocation test. 4. A few percentage of subjects with false-negative dosimeter maybe existed in the dosimeter method, especially for mild asthmatic children. .The AHR last longer than the clinical symptoms in children with asthma, and AHR should be detected continuously in asthmatic children whose clinical symptoms well controlled to judge the state of asthma.