Spirometry Terminology

Spirometry Terms simplified:

FVC: Forced (expiratory) Vital Capacity = total volume exhaled forcefully from the point of maximal inhalation.

FEV1: Forced Expiratory Volume during the first second of the test.

FEV1%: The ratio of the FEV1 to the FVC, i.e. FEV1/FVC. Identifies the percentage of total FVC exhaled during the first second of the test.

FEF25-75: Traditionally known as MMEF, (Maximal Mid-Expiratory Flow Rate) is the average flow rate between the 25% level and 75% level of the observed FVC. eg, with an observed FVC of 4.0 liters the 25% level is at 1.0 liter and the 75% level is at 3.0 liters. A line drawn through these points on the time-volume FVC curve will display this average liters-per-second flow rate.

PEFR: Peak Expiratory Flow Rate in liters per Second.

FEV#: Forced Expiratory Volume occurring within (0.5, 1, 3, 6) seconds.

FEF##: Forced Expiratory Flow occurring at the point (25, 50, 75) that is 25%, 50%, 75% from the beginning of the exhalation.

FET: Forced Expiratory Time. The total time of Exhalation expressed in seconds.

TPEF: Time to Peak Expiratory Flow Rate expressed in milliseconds, from start of exhalation.

VEZ%: Volume Extrapolated Zero, as a percentage of the FVC volume. It is earliest acceleration of the exhalation.

PIFR: Peak Inspiratory Flow Rate (during the inspiratory part of the FVL).

FIF##: Forced Inspiratory Flow rate at the point (25, 50, 75) that is 25%, 50%, 75% from the beginning of the inhalation.

FIVC: Forced Inspiratory Vital Capacity (maximal inhalation beginning from the point of maximal exhalation).

FVL: Flow Volume Loop

Post-BD: Post Bronchodilator

Pred: Predicted. The normal or predicted value for a subject of that age, height, sex, and ethnicity.

Meas: Measured. The subject’s measured results.

%Prd: Percent of predicted. Compares the subject’s results to the predicted value for each parameter (i.e., Pred/Meas = %Pred).