Small airway dysfunction in patients with idiopathic interstitial pneumonia.

Objective To explore the change of small airway function in patients with idiopathic interstitial pneumonia (IIPs).Methods 159 patients with IIPs hospitalized in the respiratory department of Beijing Chao Yang Hospital,from Jan.1999 to Feb.2007 were studied.113 of the 159 patients were with idiopathic pulmonary fibrosis (IPF),23 were with nonspecific interstitial pneumonia (NSIP) while 23 were with cryptogenic organizing pneumonia (COP).Their lung ventilation,gas exchange and small airway function were tested.Results In IIPs patients,small airway function indexes significantly declined,and maximal expiratory flow rates at 25% and 50% vital capacity (V25%,V50%) were both smaller than 80% of the predicted value.The incidence of small airway dysfunction in IPF,NSIP and COP were 51.32%,73.91% and 69.56% respectively,and among these,the difference between NSIP and IPF showed statistical significance (P0.05).Conclusion The patients with IIPs not only have restriction of ventilation function and impairment of lung diffusion function,but also have small airway dysfunction.Different types of IIPs have different incidence rates of small airway dysfunction.Patients with NSIP may have a higher incidence of small airway dysfunction than IPF.Small airway function test may contribute to the whole evaluation of pulmonary physiological function in patients with IIPs.