Airflows
This is the KEY to detecting OBSTRUCTION! The patient is
instructed to breath out as hard and fast and completely as
possible from a full inspiration. Most importantly are:
FEV1, Forced expiratory volume in 1 second
FVC, forced vital capacity
Ratio of FEV1/FVC less than 75% defines OBSTRUCTION!
All other flows may support or suggest obstruction but the
definition rest with the ratio of FEV1/FVC.