Analysis of the bronchodilation test in asthmatic children with normal forced expiratory volume in 1 second, forced vital capacity and 1-second rate / 中华实用儿科临床杂志

ABSTRACT

Objective:To evaluate the positive rate of the bronchodilation test (BDT) in asthmatic children with normal forced expiratory volume in 1 second (FEV 1), forced vital capacity (FVC) and FEV 1/FVC, so as to improve the recognition of the importance of the BDT test in asthmatic children with normal FEV 1, FVC and FEV 1/FVC. Methods:Children aged 5-14 who were diagnosed with asthma in the outpatient clinic of Shandong Provincial Hospital Affiliated to Shandong University from September 2018 to August 2019 and willing to receive pulmonary function and BDT examinations were enrolled.Data of pulmonary function of children with normal FEV 1, FVC and FEV 1/FVC were collected to analyze the rate of positive BDT results and the status of small airway function. Results:A total of 1 631 asthmatic children with normal FEV 1, FVC and FEV 1/FVC were enrolled in this study, including 1 414 children with normal pulmonary function and 217 children with small airway dysfunction.Fifteen minutes after the bronchodilator was inhaled, 127 children (87 males and 40 females) showed positive BDT results, accounting for 7.8%.Among these children, 62 cases (28.6%) with co-existing small airway dysfunction showed positive BDT results.The improvement rate of FEV 1 was 8.0% to 11.9% in 132 cases (8.1%). The FEV 1 before bronchodilator inhalation accounted for (98.5±10.3)% of the predicted value.Fifteen minutes after terbutaline sulfate inhalation, the improvement rate was 13.5% (12.5%, 16.2%). The improvement rates of forced expiratory flow at 50% of FVC exhaled (FEF 50, r=-0.339, P<0.01), forced expiratory flow at 75% of forced vital capacity exhaled (FEF 75, r=-0.400, P<0.01), maximum mid-expiratory flow(MMEF, r=-0.375, P<0.01) were negatively correlated with their baseline values.The improvement rate of FEV 1 was not associated with its baseline value ( r=-0.128, P=0.153), but negatively correlated with the baseline value of MMEF ( r=-0.231, P<0.01). Conclusions:BDT results are positive in some asthmatic children with normal FEV 1, FVC and FEV 1/FVC.It is recommended that BDT testing should be conducted as much as possible in the diagnosis and follow-up of children with typical or atypical asthma.In this way, the diagnosis can be confirmed and the current optimal results can be obtained.Meanwhile, small airway function testing is helpful for comprehensive assessment of asthma and its control level.