The present study has the following objectives:
to explore the diagnostic value of IOS before and after BPT/BDT in chronic airway disease, to assess the diagnostic accuracy of IOS in chronic airway disease with special regard to its discriminating value between asthma and chronic obstructive pulmonary disease, to evaluate the characteristics of airway resistance after BPT/BDT, to evaluate the airway reversibility and hyperresponsiveness（AHR）in asthma.
