Lung function
All patients underwent lung function tests by using Spirolab II
system(Medical International Research, Rome, Italy). It was performed by
a trained operatör, and the equipment was calibrated daily. Measured
parameters were the prebronchodilator forced expiratory volume in 1st
second(FEV1), the forced vital capacity(FVC), the FEV1 to FVC
ratio(FEV1/FVC) and the forced expiratory flow between 25% and 75% of
vital capacity(FEF25%-75%). Results were reported as
percentage of the predicted value according to
references.23