Comparative Study On Fractional Exhaled Nitric Oxide And Lung Function Of Cough Variant Asthma And Typical Asthma

Objective:Cough variant asthma is a special phenotype of typical asthma,with chronic airway inflammation and airway hyperresponsiveness（AHR）,and dry cough is often the only symptom in the clinic,which needs to be distinguished from other chronic cough diseases and its relationship with typical asthma needs to be studied.In this paper,the differences in pulmonary ventilation function and exhaled nitric oxide in patients with CVA,typical asthma and chronic cough are proposed to be compared and analyzed,so as to provide a reference for the differential diagnosis and treatment of CVA.Method:55 inpatients who were clearly diagnosed with asthma at the First Hospital of Jilin University from November 2019 to June 2021 were included,and they were divided into CA group（32 people）and CVA group（23 people）according to their symptoms.17 chronic cough inpatients（cough>8 weeks）who attended the same period of time,conducted both diastolic tests and provocation tests,and both tests had negative results.These chronic cough patients were named as a control group（CC group）.Differences in lung function,exhaled nitric oxide,and alveolar nitric oxide levels were compared across groups using retrospective analysis.Result:1.Comparison of general data:there are no statistical differences in three groups of patients in gender、age、height、weight and other parts（P>0.05）.2.Comparison of FeNO:（1）FeNO₅₀:There was no significant difference in FeNO₅₀ levels in the CVA group from the CA group and the CC control group（P>0.05）.The level of FeNO₅₀ in the CA group was significantly higher than that in the CC control group,and the difference was statistically significant（P<0.05）.（2）FeNO₂₀₀:The FeNO₂₀₀ levels in the CVA group were significantly higher than those in the CC control group（P<0.05）,and there was no statistical difference with the CA group（P>0.05）.The level of FeNO₂₀₀ in the CA group was significantly higher than that in the CC control group,and the difference was statistically significant（P<0.05）.（3）CaNO:Compared to the three groups,there is no statistical difference（P>0.05）.3.Comparison of pulmonary function:（1）The levels of FEF₇₅%pre and MMEF%pre in the CVA group were significantly lower than the CC group（P<0.05）,while the levels of FEV₁%pre、PEF%pre、FEF₂₅%pre和FEF₅₀%pre were not significantly different（P>0.05）.（2）The levels of FEV₁%pre,PEF%pre,FEF₅₀%pre and MMEF%pre in the CVA group were significantly higher than the CA group（P<0.05）,while the levels of FEF₂₅%pre and FEF₇₅%pre were not significantly different（P>0.05）.（3）Compared with the CA group and the CC group,the lung function index was significantly reduced（P<0.05）.Conclusion:1.FeNO₅₀ is helpful in diagnosing classic asthma,but not in differential diagnosis of cough variant asthma and non-asthmatic cough patients.FeNO₂₀₀ helps to differentiate between cough variant asthma and non-asthmatic cough patients.2.Most patients with typical asthma have both large and small airway dysfunction,and a small proportion of patients with cough variant asthma may have airway dysfunction,most of which present with small airway dysfunction but are milder than typical asthmatic patients.