Diagnostic value of airway resistance changes before and after maximal voluntary ventilation for patients with cough variant asthma

Objective To explore the diagnostic value of airway resistance changes before and after maximal voluntary ventilation(MVV) measurement for patients with cough variant asthma(CVA).MethodsThirty-six patients suffered from chronic cough for 3 months to 15 years were enrolled in the study.Changes of airway resistance before and after performing MVV were measured and compared with the results of bronchial provocation test(BPT) or bronchodilation test.The airway resistance was measured by impulse oscillometry and the changes of ZRS and R5 above 20% or R20 above 15% were judged as positive.Results 14 subjects showed significant changes of airway resistance before and after MVV in 15 subjects with BPT positive and 9 subjects showed no significant changes of airway resistance in 10 subjects with BPT negative.All 11 patients underwent bronchodilation test yielded positive result,meanwhile airway resistance showed significant changes.Total consistency ratio was 94.4%[(14+9+11)/36].Conclusion The airway responsiveness can be well reflected by airway resistance changes before and after MVV which may be a new convenient and more safe approach for diagnosis of CVA.