What pulmonary function test measures the total air volume that can be exhaled after a deep breath?

The correct answer, which measures the total air volume that can be exhaled after a deep breath, is forced vital capacity (FVC). FVC represents the maximum amount of air that can be forcibly exhaled from the lungs after taking a deep breath in. This measurement is essential for assessing lung function and diagnosing various pulmonary conditions because it evaluates the lungs' capacity to hold and expel air, reflecting both the elasticity of the lung tissue and the strength of the respiratory muscles.

In contrast, forced expiratory volume (FEV) specifically measures the volume of air that can be forcibly exhaled in a specified time interval, commonly the first second of exhalation (FEV1), but does not encompass the total air exhaled after a full inhalation. Residual volume (RV) refers to the amount of air remaining in the lungs after a maximal exhalation, which does not measure the air exhaled but rather the air that is always present in the lungs. Inspiratory capacity (IC) measures the maximum volume of air that can be inhaled after a normal exhalation, which is not concerned with the exhaled volume following a deep breath.

Therefore, FVC is the key measurement for understanding the