The Association Between Small Airway Function And FEV1/FVC In Asthmatic Children With Persistent Small Airway Obstruction

Objective:To investigate the association of small airway function with forced expiratory volume in one second/forced vital capacity（FEV1/FVC）and the effect of inhaled corticosteroids（ICS）/long—acting 2 receptor agonist（LABA）combined preparation on small airway dysfunction.Methods:Asthmatic children at remission stage with persistent small airway dysfunction of outpatient from January 2017 to January 2021,aged from 4 to 14 years were selected.The gender,age,follow-up time,asthma symptom,asthma drugs and treatment time were collected and recorded.Pulmonary function data were collected to analyze the correlation between small airway function and FEV1/FVC,and to analyze the improvement of small airway dysfunction with the treatment of ICS/LABA combined preparation.SPSS 26.0 software package was used for statistical analysis.Results:39 children were included in the study totally,with 32 boys and 7 girls.The youngest child was 4 years old and the oldest was 14.The mean age of the subjects was 7.69±2.483 years old.The results showed that FEF₅₀(MEF₅₀)was correlated to FEV1/FVC（r=0.773,P<0.01）,FEF₇₅(MEF₂₅)was correlated to FEV1/FVC（r=0.800,P<0.01）,and FEF_25-75（MMEF）was correlated to FEV1/FVC（r=0.817,P<0.01）.A total of 29children were treated with ICS/LABA for 1 year.Compared with the data before treatment,FEF₅₀(MEF₅₀)increased by 2.2069±10.2869（P>0.05）,FEF₇₅(MEF₂₅)increased by 1.8172±12.3588（P>0.05）,and FEF_25-75（MMEF）increased by 2.2759±11.3051（P>0.05）.A total of 15 children were treated with ICS/LABA for 2 years.Compared with before treatment,FEF₅₀(MEF₅₀)increased by 1.0600±10.0645（P>0.05）,FEF₇₅(MEF₂₅)decreased by 0.5533±10.1646（P>0.05）,and FEF_25-75（MMEF）decreased by0.1133±10.9466（P>0.05）.Conclusions:small airway function parameters including FEF₅₀(MEF₅₀),FEF₇₅(MEF₂₅),FEF_25-75（MMEF）are positively correlated with FEV1/FVC.Treated with ICS/LABA combined preparation for 1 or 2 years did not significantly improve small airway disorder in asthmatic children with persistent small airway dysfunction in remission stage.