Volume-adjusted maximal mid-expiratory flow (Iso-volume FEF25-75%): definition of "Significant" responsiveness in healthy, normal subjects.

Iso-volume FEF25-75% was evaluated in 30 non-smoking, healthy subjects (16-58 years) to define the percentage change over baseline required for responsiveness to inhaled bronchodilators using this measurement to be significant. The mean percentage change from baseline for Iso-volume FEF25-75% was 15.3% +/- 17.2% (1 SD). Improvement of greater than 49.6% (mean +/- 2 SD) over baseline is required for the change reflected by the Iso-volume FEF25-75% to be significant.