FEV1/FVC ratio

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Lungvolumes Updated.png
TLC

Total lung capacity: the volume in the lungs at maximal

inflation, the sum of VC and RV.
TV

Tidal volume: that volume of air moved into or out of the lungs during quiet breathing (VT indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation,

the symbol VT or VT is used.)
RV

Residual volume: the volume of air remaining in the lungs

after a maximal exhalation
ERV

Expiratory reserve volume: the maximal volume of air that can

be exhaled from the end-expiratory position
IRV

Inspiratory reserve volume: the maximal volume that can be

inhaled from the end-inspiratory level
IC Inspiratory capacity: the sum of IRV and TV
IVC

Inspiratory vital capacity: the maximum volume of air inhaled

from the point of maximum expiration
VC

Vital capacity: the volume of air breathed out after the

deepest inhalation.
VT

Tidal volume: that volume of air moved into or out of the lungs during quiet breathing (VT indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation,

the symbol VT or VT is used.)
FRC

Functional residual capacity: the volume in the lungs at the

end-expiratory position
RV/TLC% Residual volume expressed as percent of TLC
VA Alveolar gas volume
VL

Actual volume of the lung including the volume of the

conducting airway.
FVC

Forced vital capacity: the determination of the vital

capacity from a maximally forced expiratory effort
FEVt

Forced expiratory volume (time): a generic term indicating the volume of air exhaled under forced conditions in the first t

seconds
FEV1

Volume that has been exhaled at the end of the first second

of forced expiration
FEFx

Forced expiratory flow related to some portion of the FVC

curve; modifiers refer to amount of FVC already exhaled
FEFmax

The maximum instantaneous flow achieved during a FVC

maneuver
FIF

Forced inspiratory flow: (Specific measurement of the forced inspiratory curve is denoted by nomenclature analogous to that for the forced expiratory curve. For example, maximum inspiratory flow is denoted FIFmax. Unless otherwise specified, volume qualifiers

indicate the volume inspired from RV at the point of measurement.)
PEF

Peak expiratory flow: The highest forced expiratory flow

measured with a peak flow meter
MVV

Maximal voluntary ventilation: volume of air expired in a

specified period during repetitive maximal effort

The FEV1/FVC ratio, also called Tiffeneau-Pinelli[1] index, 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 expiration.[4] See the Wikipedia article on spirometry for the definitions of FEV1 and FVC.

Normal values are approximately 80%.[5] Predicted normal values can be calculated online and depend on age, sex, height, mass 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[edit]

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.[4] More specifically, according to the National Institute for Clinical Excellence, the diagnosis of COPD is made when the FEV1/FVC ratio is less than 60%, however, other authoritative bodies have different diagnostic cutoff points.[6] The Global Initiative for Obstructive Lung Disease[7] (GOLD) criteria also require that values are after bronchodilator medication has been given to make the diagnosis. According to the European Respiratory Society (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.[6]

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 an increased FEV1 value (because of the decreased compliance associated with the presence of fibrosis in some pathological conditions).[4]

References[edit]

  1. ^ Minelli R. Appunti dalle lezioni di fisiologia umana. La Goliardica Pavese, Pavia, 1992.
  2. ^ Swanney MP, Ruppel G, Enright PL, et al (December 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. 
  3. ^ Sahebjami H, Gartside PS (December 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. 
  4. ^ a b c http://www.gp-training.net/protocol/respiratory/copd/spirometry.htm
  5. ^ "Forced Expiration". Retrieved 2009-04-21. 
  6. ^ a b Nathell, L.; Nathell, M.; Malmberg, P.; Larsson, K. (2007). "COPD diagnosis related to different guidelines and spirometry techniques". Respiratory research 8 (1): 89. doi:10.1186/1465-9921-8-89. PMC 2217523. PMID 18053200.  edit [1]
  7. ^ [2]