Pulmonary Physiology, Gas Pressures & Volumes, Dr. D. Penney





Figure 1.02. A Forced Ventilatory Capacity (FVC) recording on which the volumes expired at the end of 0.5, 1, 2 and 3 seconds are indicated (FEV0.5, FEV1.0, FEV2.0, FEV3.0).

Forced Expiratory Volume is greatest after 1/2 second and progressively decreases as expiration continues. The percentage of air expired at the end of the 1st, 2nd, and 3rd seconds as a percentage of the FVC are 83%, 94%, and 97%.

Air flow falls off as the lungs are emptied because as the lungs collapse, the air tubes are squeezed shut, raising resistance to flow.



Last Changed 05/13/01


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