FEV1/FVC ratio
The FEV1/FVC ratio, also called Tiffeneau index, 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]
A derived value of FEV1% is FEV1% predicted, which is defined as FEV1% of the patient divided by the average FEV1% in the population for any person of similar age, sex and body composition.
Disease states
In obstructive lung disease, the FEV1 is reduced due to obstruction to air escape. Thus, the FEV1/FVC ratio will be reduced.[3] More specifically, the diagnosis of COPD is made when the FEV1/FVC ratio is less than 70%.[5] The Global Initiative for Obstructive Lung Disease (GOLD) criteria also require that values are after bronchodilator medication has been given to make the diagnosis, and the British National Institute for Health and Clinical Excellence (NICE) criteria also require FEV1% to be less than 80% of predicted.[5] According to the European Respiratory Society (ERS) criteria, it is FEV1% predicted that defines when a patient has COPD, that is, when FEV1% predicted is less than 88% pred for men, or less than 89% for women.[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.[3]
References
- ^ Swanney MP, Ruppel G, Enright PL; et al. (2008). "Using the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction". Thorax. 63 (12): 1046–51. doi:10.1136/thx.2008.098483. PMID 18786983.
{{cite journal}}: Explicit use of et al. in:|author=(help); Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Sahebjami H, Gartside PS (1996). "Pulmonary function in obese subjects with a normal FEV1/FVC ratio". Chest. 110 (6): 1425–9. doi:10.1378/chest.110.6.1425. PMID 8989055.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ a b c http://www.gp-training.net/protocol/respiratory/copd/spirometry.htm
- ^ "Forced Expiration". Retrieved 2009-04-21.
- ^ a b c Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1186/1465-9921-8-89, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1186/1465-9921-8-89instead. [1]