forced expiratory volume in 1 second (FEV1)

Indications

• FEV1 is used in connection with FVC for assessing obstructive lung disease.

Clinical significance

Table

FEV1/FVC	Assessment
> 75%	normal
60-74%	mild obstruction
45-59%	moderate obstruction
< 40%	severe obstruction

Notes

• an isolated decrease in FEF25-75 is indicative of small airway disease

More general terms

• pulmonary function test (PFT)

More specific terms

• FEV1 for COPD <40% of predicted
• FEV1 for COPD >40% of predicted

Component of

• FEV1/FVC