Acute postbronchodilator changes in pulmonary function parameters in patients with chronic airways obstruction.

Pulmonary function studies were performed before and after one-time administration of an inhaled bronchodilator to ascertain the relative diagnostic value of using FVC, FEF25-75%, static lung volumes, Raw, and/or sGaw measurements, in addition to the FEV1, to assess the reversibility of chronic airways obstruction in nonasthmatic patients. A total of 517 patients underwent 686 spirometric tests, 264 (38 percent) of which disclosed a significant response to bronchodilators. In 247 (93 percent) studies, this response included a significant change in FEV1 and/or FEF25-75%, while in 17 studies (7 percent), the postbronchodilator improvement was seen exclusively in the FVC measurement. It is concluded that, in the clinical setting, analyzing static lung volumes, Raw, sGaw, and spirometric parameters other than the FEV1, seldom yields meaningful additional information regarding the reversibility of chronic airways obstruction in nonasthmatic patients. Finally, potentially misleading results can be seen in a relatively small proportion of studies due to errors in the FVC and/or FEF25-75% measurements.