|Measurements made in Spirometry
||Vital capacity (Slow vital capacity)
||Maximal amount of air exhaled steadily from full inspiration to maximal expiration (not time dependent). It should be >80% of predicted, reduced in restrictive disease.
||Forced vital capacity
||Volume of lungs from full inspiration to forced maximal expiration. It is reduced in restrictive disease, and in obstructive disease if air trapping occurs.
||Forced expiratory volume in one second
||Volume of air expelled in the first second of a forced expiration. Reduced in both obstructive and restrictive disease.
||Forced expiratory ratio (FEV1/FVC)x100
||Percentage of FVC expelled in the first second of a forced expiration.
Normal in restrictive disease - reduced in obstructive disease.
||Forced Expiratory Flow between 25-75%
||Average expiratory flow rate at the middle part of forced expiration. It is a more sensitive indication of what is happening in the middle/lower airways, but is not as reproducible as FEV1. Normal in restrictive disease.
||Peak expiratory flow rate
||Maximum rate of airflow achieved during expiration