
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 (TV indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation, the symbol TV or V_{T} 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 endexpiratory position 

IRV  Inspiratory reserve volume: the maximal volume that can be inhaled from the endinspiratory 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. 

V_{T}  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 TV or V_{T} is used.) 

FRC  Functional residual capacity: the volume in the lungs at the endexpiratory position 

RV/TLC%  Residual volume expressed as percent of TLC 

V_{A}  Alveolar gas volume 

V_{L}  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 

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

FEV_{1}  Volume that has been exhaled at the end of the first second of forced expiration 

FEF_{x}  Forced expiratory flow related to some portion of the FVC curve; modifiers refer to amount of FVC already exhaled 

FEF_{max}  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 FIF_{max}. 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 

