The FEV1/FVC ratio, also called Tiffeneau-Pinelli index, is a calculated ratio used in the diagnosis of
obstructive and
restrictive lung disease
Restrictive lung diseases are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygenat ...
.
It represents the proportion of a person's
vital capacity
Vital capacity (VC) is the maximum amount of air a person can inhale after a maximum exhalation. It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. It is approximately equal to Forced Vital Capacity ( ...
that they are able to expire in the first second of forced expiration (
FEV1
Spirometry (meaning ''the measuring of breath'') is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is h ...
) to the full, forced vital capacity (
FVC).
[Interpreting spirometry](_blank)
. gp-training.net The result of this ratio is expressed as FEV1%.
Normal values are approximately 75%.
Predicted normal values can b
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.
More specifically, according to the
National Institute for Clinical Excellence
The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care in England that publishes guidelines in four areas:
* the use of health technologies withi ...
, the diagnosis of
COPD
Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...
is made when the FEV
1/FVC ratio is less than 0.7 or the FEV
1 is less than 75% of predicted;
Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care (partial update)
NICE.org.uk. June 2010 however, other authoritative bodies have different diagnostic cutoff points.[ The ]Global Initiative for Chronic Obstructive Lung Disease The Global Initiative for Chronic Obstructive Lung Disease (GOLD) is a non-profit organization started by the World Health Organization and the US National Heart, Lung, and Blood Institute in 1997 to improve care for chronic obstructive pulmonary di ...
criteria also require that values are after bronchodilator
A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lung ...
medication has been given to make the diagnosis. According to the European Respiratory Society
The European Respiratory Society, or ERS, is a non-profit organization with offices in Lausanne, Brussels and Sheffield. It was founded in 1990 in the field of respiratory medicine. The organization was formed with the merger of the Societas Euro ...
(ERS) criteria, it is ''FEV1% predicted'' that defines when a patient has COPD—that is, when the patient's FEV1% is less than 88% of the predicted value for men, or less than 89% for women.
References
{{DEFAULTSORT:Fev1 Fvc Ratio
Respiratory physiology