FEV1/FVC ratio
< FEV1
The FEV1/FVC ratio is a calculated ratio used in the diagnosis of obstructive and restrictive lung disease.
It represents the proportion of the forced vital capacity exhaled in the first second[1].
Disease States
In obstructive lung disease, the FEV1 is reduced due to obstruction to air escape. Thus, the FEV1/FVC ratio will be reduced[2].
In restrictive lung disease, the FEV1 and FVC are equally reduced due to fibrosis or other lung pathology (not obstructive pathology). Thus, the FEV1/FVC ratio should be approximately normal[3].
References