Methods: Subjects, who had never been diagnosed as asthma, were consecutively enrolled from June 1st to November 31st, 2013. Based on the subject's past and family history, we evaluated the possibility of asthma by scoring each subject on a scale of 0 to 10 (pre asthma score). The subjects were randomly assigned the bronchodilator tests of the two dosages without physician’s knowledge and performed the BDR tests using the spirometric and impulse oscillometric lung function. Asthma diagnosis (post asthma score) was later re-evaluated after BDR test.
Results: A total of 119 subjects participated in this study, and the mean age was 7.8 (±3.6) years. The number of participants who were assigned 2 puffs and 4 puffs were 59 and 57, respectively. The mean age of 4 puffs group was older than the 2 puffs group (p=0.012). Before the BDR test, there was no statistical difference in pre asthma score between the two groups (2 puffs = 5.46 vs. 4 puffs = 4.9) (p=0.428). After the BDR test, the post asthma scores of the two groups were 5.8 (±3.4) and 4.7 (±3.4), respectively, which also showed no statistically significant difference between the two groups (p=0.098). The pre asthma score was significantly correlated with forced expiratory volume in 1 sec/forced vital capacity (FEV1/FVC) (r=-0.212, p=0.021), forced expiratory flow at 25% to 75% (FEF25-75) of FVC (r=-0.184, p=0.046) and reactance at 5 Hz (Xrs5) (r=0.201, p=0.029) Z score. However, there was no significant difference in FEV1 and FEV1/FVC of spirometric parameters, and resistance at 5 Hz (Rrs5) and Xrs5 of impulse oscillometry system (IOS) value between the 2 puffs group and 4 puffs group.
Conclusion: There was no significant relationship between the amount of bronchodilators administered and the small airway dysfunction in children. However, Xrs5 showed a significant correlation with the physician's asthma predictive score.