In this study we hypothesized that bronchodilator inhalation reduces thoracic gas compression (TGC) and such a reduction explains in part the FEV1 improvement with a bronchodilator. To test this hypothesis, we studied normal subjects as well as subjects with COPD and asthma before and after inhalation of albuterol.
We measured lung mechanic parameters including FEV1, peak expiratory flow (PEF), expiratory lung resistance (Rle), esophageal pressure, and total lung capacity (TLC) before and after inhalation of 180 mcg of albuterol in the study subjects. We used a novel method to estimate FEV1 (NFEV1) corrected for effect of TGC.
Our results demonstrate that bronchodilator inhalation reduced TGC and Rle; and increased PEF and FEV1. Furthermore, TGC reduction with bronchodilator explained 50% of increase in FEV1 post bronchodilator.
We concluded that inhalation of bronchodilator decreased thoracic gas compression by improving expiratory flow limitation, and therefore, TGC reduction explains in part the improvement in FEV1 with bronchodilator.
Special attention needs to be given to consitency in performing pulmonary function testing. Variable effort may alter the FEV1 without any true effect from bronchodilator.
A. Sharafkhaneh, None.