FVC to slow inspiratory vital capacity ratio: a potential marker for small airways obstruction.

Significant, yet small decreases in FVC/SVC ratio occur in patients in whom BOS develops, independent from changes in FEV(1). At a group level, FVC/SVC ratio is able to detect small airways changes. These results merit prospective studies to determine the sensitivity of FVC/SVC ratio to quantifying small airways dysfunction at an individual level and in other airway diseases.