FEV1/FVC ratio
The FEV1/FVC ratio, also called modified Tiffeneau-Pinelli index,[1] is a calculated ratio used in the diagnosis of obstructive and restrictive lung disease.[2][3] It represents the proportion of a person's vital capacity that they are able to expire in the first second of forced expiration (FEV1) to the full, forced vital capacity (FVC).[4] FEV1/FVC ratio first proposed by E.A. Haensler in 1950.[5] The FEV1/FVC index should not be confused with the FEV1/VC index (Tiffeneau-Pinelli index) as they are different, although both are intended for diagnosing airway obstruction. Current recommendations for diagnosing pulmonary function recommend using the modified Tiffeneau-Pinelli index (also known as the Haensler index).[6] This index is recommended to be represented as a decimal fraction with two digits after the decimal point (for example, 0.70).
Normal values are approximately 75%.[7] Predicted normal values can be calculated online and depend on age, sex, height, and ethnicity as well as the research study that they are based upon.
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 an obstruction of air escaping from the lungs. Thus, the FEV1/FVC ratio will be reduced.
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, or even increased due to a decrease in magnitude of FVC as compared to FEV1 (because of the decreased compliance associated with the presence of fibrosis in some pathological conditions).[4]
References
- ^ Minelli R. Appunti dalle lezioni di fisiologia umana. La Goliardica Pavese, Pavia, 1992.
- PMID 18786983.
- S2CID 25461249. Archived from the original(PDF) on 2019-02-19.
- ^ a b c Interpreting spirometry Archived 2008-07-25 at the Wayback Machine. gp-training.net
- ^ Petty, Thomas L. "The history of COPD" (PDF). nlhep.org.
- ^ Mirsadraee M, Salarifar E, Attaran D. Evaluation of Superiority of FEV1/VC Over FEV1/FVC for Classification of Pulmonary Disorders. J Cardiothorac Med. 2015; 3(4):355-359. Archived 2017-11-16 at the Wayback Machine
- ^ "Forced Expiration". Johns Hopkins University.
- ^ Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care (partial update). NICE.org.uk. June 2010
- ^ Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care (partial update). NICE.org.uk. June 2010
- ^ PMID 18053200.