FEV1/FVC ratio

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Lungvolumes.svg
TLCTotal lung capacity: the volume in the lungs at maximal inflation
TVTidal 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.)
RVResidual volume: the volume of air remaining in the lungs after a maximal exhalation
ERVExpiratory reserve volume: the maximal volume of air that can be exhaled from the end-expiratory position
IRVInspiratory reserve volume: the maximal volume that can be inhaled from the end-inspiratory level
ICInspiratory capacity: the sum of IRV and TV
IVCInspiratory vital capacity: the maximum volume of air inhaled from the point of maximum expiration
VCVital capacity: the volume equal to TLC − RV
VTTidal 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.)
FRCFunctional residual capacity: the volume in the lungs at the end-expiratory position
RV/TLC%Residual volume expressed as percent of TLC
VAAlveolar gas volume
VLActual volume of the lung including the volume of the conducting airway.
FVCForced vital capacity: the determination of the vital capacity from a maximally forced expiratory effort
FEVtForced expiratory volume (time): a generic term indicating the volume of air exhaled under forced conditions in the first t seconds
FEV1Volume that has been exhaled at the end of the first second of forced expiration
FEFxForced expiratory flow related to some portion of the FVC curve; modifiers refer to amount of FVC already exhaled
FEFmaxThe maximum instantaneous flow achieved during a FVC maneuver
FIFForced 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.)
PEFThe highest forced expiratory flow measured with a peak flow meter
MVVMaximal voluntary ventilation: volume of air expired in a specified period during repetitive maximal effort
 
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Lungvolumes.svg
TLCTotal lung capacity: the volume in the lungs at maximal inflation
TVTidal 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.)
RVResidual volume: the volume of air remaining in the lungs after a maximal exhalation
ERVExpiratory reserve volume: the maximal volume of air that can be exhaled from the end-expiratory position
IRVInspiratory reserve volume: the maximal volume that can be inhaled from the end-inspiratory level
ICInspiratory capacity: the sum of IRV and TV
IVCInspiratory vital capacity: the maximum volume of air inhaled from the point of maximum expiration
VCVital capacity: the volume equal to TLC − RV
VTTidal 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.)
FRCFunctional residual capacity: the volume in the lungs at the end-expiratory position
RV/TLC%Residual volume expressed as percent of TLC
VAAlveolar gas volume
VLActual volume of the lung including the volume of the conducting airway.
FVCForced vital capacity: the determination of the vital capacity from a maximally forced expiratory effort
FEVtForced expiratory volume (time): a generic term indicating the volume of air exhaled under forced conditions in the first t seconds
FEV1Volume that has been exhaled at the end of the first second of forced expiration
FEFxForced expiratory flow related to some portion of the FVC curve; modifiers refer to amount of FVC already exhaled
FEFmaxThe maximum instantaneous flow achieved during a FVC maneuver
FIFForced 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.)
PEFThe highest forced expiratory flow measured with a peak flow meter
MVVMaximal 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 volume of air exhaled in the first second.[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, weight 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.[4] More specifically, the diagnosis of COPD is made when the FEV1/FVC ratio is less than 70%.[6] The Global Initiative for Obstructive Lung Disease (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

  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. http://thorax.bmj.com/cgi/pmidlookup?view=long&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. http://www.chestjournal.org/cgi/pmidlookup?view=long&pmid=8989055. 
  4. ^ a b c http://www.gp-training.net/protocol/respiratory/copd/spirometry.htm
  5. ^ "Forced Expiration". http://oac.med.jhmi.edu/res_phys/Encyclopedia/ForcedExpiration/ForcedExpiration.HTML. 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. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2217523/.  edit [1]