The FEV1/FVC ratio is a calculated ratio used in the diagnosis of obstructive and restrictive lung disease.^[1][2]

It represents the proportion of the forced vital capacity exhaled in the first second^[3].

Normal values are approximately 80%.^[4]

[edit] Disease states

In obstructive lung disease, the FEV1 is reduced due to obstruction to air escape. Thus, the FEV1/FVC ratio will be reduced^[5].

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^[6].

[edit] References