A Clinical Study On The Measurement Of Small Airway Function In Asthmatic Patients By Impulse Oscillometry System

Objective:To explore the application value of impulse oscillometry in small airway function in chronic persistent asthma patients with different severity by using impulse oscillometry and spirometry.Methods:The 154 patients with chronic persistent asthma were collected from July 2016 to June 2017 in the Department of Respiratory and Critical Care Medicine of Shanxi Dayi Hospital Affiliated to Shanxi Medical University and divided into three groups according to the percentage of forced expiratory volume in one second as predicted（FEV₁%Pre）:mild group（FEV₁%Pre≥80%,n=75）,moderate group（60%≤FEV₁%Pre<80%,n=43）and severe group（FEV₁%Pre<60%,n=36）.The 40 healthy adults in the same period were selected as healthy control group.Spirometry and impulse oscillometry parameters were obtained from every subject.Impulse oscillometry parameters,such as respiratory resistance at 5Hz（R5）,respiratory resistance at 20Hz（R20）,absolute difference in resistance between 5Hz and 20Hz（R5-20）,relative difference in resistance between 5Hz and 20Hz（R5-20%）,peripheral resistance（Rp）,Reactance at 5 Hz（X5）.Pulmonary function indicators include forced expiratory volume in one second（FEV₁）,FEV₁%pre,ratio of forced expiratory volume in one second to forced vital capacity（FEV₁/FVC）,forced expiratory flow（FEF）,FEF_50%,FEF_25%-75%,peak expiratory flow（PEF）were recorded.Results:（1）There was no significant difference in gender and mean age between asthma patients and healthy controls（P>0.05）.（2）Compared with healthy control group,FEV₁/FVC was significantly reduced in moderate group and severe group,and the FEF_25%-75%,FEF_50%and PEF were significantly decreased in all the asthma groups（P<0.01）.（3）Compared with healthy control group,the R5,R20,R5-20,R5-20%,Rp and X5 were significantly increased in mild group,moderate group and severe group（P<0.01）.There were statistically significant differences in the above indicators among three asthma groups（P<0.01）.（4）The correlation coefficients of R5,R5-20,R5-20%,Rp and X5 with FEF_25%-75%were-0.611,-0.587,-0.506,-0.624 and 0.560,respectively.Among them,R5,R5-20,R5-20%and Rp were negatively correlated with FEF_25%-75%（P<0.01）.X5 was positively correlated with FEF_25%-75%（P<0.01）.And the order of correlation is Rp,R5,R5-20,X5 and R5-20%.Conclusion:Indicators reflecting small airway function by impulse oscillometry in patients with chronic persistent asthma are significantly increased,and have a good correlation with routine lung function FEF_25%-75%and the severity of asthma.