The McGill Physiology Virtual Lab

Respiration Laboratory

Theory> Ventilatory Function tests: Dynamic Lung Volumes
  Lung volumes that depend upon the rate at which air flows out of the lungs are termed dynamic lung volumes. There are various dynamic tests: Forced Vital Capacity test, and the Maximum Voluntary Ventilation test.
The Forced Vital Capacity (FVC) is the volume of gas that can be exhaled as forcefully and rapidly as possible after a maximal inspiration. Normally FVC = VC, however in certain pulmonary diseases (characterized by increased airway resistance), FVC is reduced.
From the FVC test, we can also determine the Forced Expiratory Volume in 1 sec (FEV1), which is the maximum volume of air that can be exhaled in a 1 sec time period. Normally the percentage of the FVC that can be exhaled during 1 sec is around 80% (i.e. FEV1/FVC=80%).
Maximum Voluntary Ventilation (MVV) is the largest volume of air that can be breathed in and out of the lungs in 1 minute. It will be reduced in pulmonary diseases due to increases in airway resistance or changes in compliance.


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