Spirometry Parameters

There are many different parameters in spirometry. The table below gives an overview of the most commenly used spirometry values and explains what they represent.

Volume parameters

These parameters represent volumes and can be read from the volume-time graph:

ParameterDefinition
FVCspirometry fvcForced Vital Capacity:
Total expired volume of the FVC test
FEV1spirometry fev1Forced Expiratory Volume in the 1st second:
Volume expired in the first second of the FVC test
FEV.5spirometry fev0.5Forced Expiratory Volume in the 1st 0.5 second:
Volume expired in the first 0.5 second of the FVC test, mainly used in pediatrics
FEV3spirometry fev3Forced Expiratory Volume in the 1st 3 seconds:
Volume expired in the first 3 seconds of the FVC test
FEV6spirometry fev6Forced Expiratory Volume in the 1st 6 seconds:
Volume expired in the first 6 seconds of the FVC test
FEV1/FVC ratio
(FEV1%)		spirometry fev1-ratioFEV1-ratio (Tiffeneau index):
The percentage of total expired volume that was expired in the first second
FEV3/FVC ratio
(FEV3%)		spirometry fev3-ratioThe percentage of air expired in the first 3 seconds, compared to total expired volume
FEV1/FEV6 ratio
(FEV6%)		spirometry fev6-ratioThe percentage of air expired in the first second, compared to volume expired after 6 seconds
FIVCspirometry fivcForced Inspiratory Vital Capacity:
Total inspired volume after performing the expiratory FVC and reinspiring completely
FIV1spirometry fiv1Forced Inspiratory Volume in the 1st second:
The volume inspired in the first second of the FIVC
FIV1/FIVC ratio
FIV%		spirometry fiv1-ratioInspiratory Tiffeneau:
Percentage of volume inspired in the 1st second compared to the total inspired volume

Flow parameters

These parameters represent flows and can be read from the flow-volume loop:

ParameterDefinition
PEFspirometry pefPeak Expiratory Flow:
Maximum flow during the FVC test, should be attained within 100 milliseconds after the start of the FVC test
PIFspirometry pifPeak Inspiratory Flow:
Maximum flow attained during an FIVC test
FEF2575spirometry fef2575spirometry fef2575Forced Expiratory Flow between 25% and 75% of FVC
Can be visually assessed in the flow-volume loop and calculated with values from the volume-time graph
FEF25spirometry fef25Forced Expiratory Flow at 25% of expired volume during FVC test
FEF50spirometry fef50Forced Expiratory Flow at 50% of expired volume during FVC test
FEF75spirometry fef75Forced Expiratory Flow at 75% of expired volume during FVC test

Other

These parameters can also be measured during a spirometry test:

ParameterDefinition
FETspirometry fetForced Expiratory Time:
Total time it takes to expire FVC
ELAEstimated Lung Age:
An attempt to translate spirometry values into a value that can be understood by the uneducated patient. ELA compares the spirometry test (usually FEV1) with predicted values for different ages and tells which age corresponds best with the performed values. This is a good tool to promote smoking cessation.

For a more in depth explanation on the different spirometry parameters go to our page on the different spirometry tests.