The study of bronchial hyperresponsiveness in asthmatic children by forced oscillation technique

We have studied the bronchial hyperresponsiveness (BHR) of children with normal controls and asthma by methacholine inhalation challenge, using a forced oscillation method. Four parameters, respiratory conductance (Grs), bronchial responsiveness (PD₃₅Grs), bronchial sensitivity (Dmin) and reactivity (SGrs) were studied. There were three patterns of dose-response curves identified in this study, which were significantly correlated to the clinical severity of asthma. (r=0.848, p<0.001, Spearman's rank correlation). There were significant negative correlations between control Rrs (Rrs cont.) and age (r=0.514, p<0.001) or body height (r=0.685, p<0.001). Positive correlations between SGrs and subjects' age (r=0.457, p<0.001) and body height (r=0.496, p<0.001) were also noted. In the normal controls, Dmin and PD₃₅Grs were over 25 units and 50 units, respectively. The Grs for normal children was statistically higher than that of asthmatic children (p<0.05). In the asthmatic children, there were significant differences among all subgroups in PD₃₅Grs (p<0.001) and Dmin (p<0.01). In summary, the bronchial provocation test using the forced oscillation technique is simple, fast and easy to be applied to children. In addition to being capable of investigating BHR, it may offer valuable intormation for the clinical diagnosis and treatment of asthmatic children.