What pulmonary function test is primarily used to measure forced expiratory volume?

Spirometry is the primary pulmonary function test used to measure forced expiratory volume (FEV). This parameter is crucial in assessing obstructive and restrictive lung diseases. During the spirometry test, the patient is asked to take a deep breath and then exhale forcefully into a spirometer. The device measures how much air is expelled and how quickly, providing important data about lung function.

In particular, FEV measures the volume of air that can be forcefully exhaled in a specified time, typically the first second of exhalation (FEV1). This measurement, along with forced vital capacity (FVC), is fundamental in diagnosing conditions like asthma and chronic obstructive pulmonary disease (COPD).

While lung volume measurement assesses the total volume of air in the lungs, the diffusion capacity test evaluates the lungs' ability to transfer gas from inhaled air to the bloodstream. Peak flow measurement provides an indication of how quickly air can be exhaled but does not offer the detail found in spirometry regarding the volume of air exhaled at specific intervals, particularly during forced expiration. Thus, spirometry stands out as the most relevant test for directly measuring forced expiratory volume.