Overview of parameters in spirometry

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
FVCForced Vital Capacity:
Total expired volume of the FVC test
FEV1Forced Expiratory Volume in the 1st second:
Volume expired in the first second of the FVC test
FEV.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
FEV3Forced Expiratory Volume in the 1st 3 seconds:
Volume expired in the first 3 seconds of the FVC test
FEV6Forced Expiratory Volume in the 1st 6 seconds:
Volume expired in the first 6 seconds of the FVC test
FEV1/FVC ratio
(FEV1%)
Tiffeneau index:
The percentage of total expired volume that was expired in the first second
FEV3/FVC ratio
(FEV3%)
The percentage of air expired in the first 3 seconds, compared to total expired volume
FEV1/FEV6 ratio
(FEV6%)
The percentage of air expired in the first second, compared to volume expired after 6 seconds
FIVCForced Inspiratory Vital Capacity:
Total inspired volume after performing the expiratory FVC and reinspiring completely
FIV1Forced Inspiratory Volume in the 1st second:
The volume inspired in the first second of the FIVC
FIV1/FIVC ratio
FIV%
Inspiratory 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
PEFPeak Expiratory Flow:
Maximum flow during the FVC test, should be attained within 100 milliseconds after the start of the FVC test
PIFPeak Inspiratory Flow:
Maximum flow attained during an FIVC test
FEF2575Forced Expiratory Flow between 25% and 75% of FVC
FEF25Forced Expiratory Flow at 25% of expired volume during FVC test
FEF50Forced Expiratory Flow at 50% of expired volume during FVC test
FEF75Forced Expiratory Flow at 75% of expired volume during FVC test

Other

These parameters can also be measured during a spirometry test:

ParameterDefinition
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.

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