Lung Volumes
Lung Volumes
Ventilation describes the process by which air moves in and out of the lungs. Lung volumes are pivotal in understanding the efficiency of ventilation as they are directly correlated.
Lung volumes may also serve as diagnostic indicators for respiratory health and provide key metrics by which pulmonary performance can be monitored.
Note: A lung capacity is the sum of two or more volumes.
The amount of air exhaled after a maximal inhalation. (~ 4500 mls)
VC = TV + IRV + ERV
The total amount of air the lungs can accommodate. (~ 6000 mls)
TLC = TV + IRV + ERV + RV
The amount of air left in the lungs at the end of normal expiration. (~ 3000 mls)
FRC = ERV + RV
Tidal Volume (TV)
The amount of air displaced during normal breathing without any excessive effort. (~500 mls)
Inspiratory Reserve Volume (IRV)
The amount of air that can be forcibly inhaled after a normal tidal volume. (~2500 mls)
Expiratory Reserve Volume (ERV)
The amount of air that can be forcibly exhaled after a normal tidal volume. (~1500 mls)
Vital Capacity (VC)
Residual Volume (RV)
The amount of air left in the lungs after maximal exhalation. (~ 1500 mls)
Total Lung Capacity (TLC)
Functional Residual Capacity (FRC)
* Values are typical for a 70kg man
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Introduction to Acute Respiratory Failure
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