What does FEV1 measure in a pulmonary function test?

FEV1, or Forced Expiratory Volume in one second, is a key measurement in pulmonary function tests that quantifies the maximum amount of air an individual can forcibly exhale in one second following a deep inhalation. This measurement is critical for evaluating lung function and diagnosing respiratory conditions, particularly asthma and chronic obstructive pulmonary disease (COPD).

A primary reason FEV1 is so significant is that it helps determine how well the lungs are functioning and can highlight any obstruction to airflow within the lungs. A decreased FEV1 relative to predicted values may indicate obstructive lung disease, as it reflects reduced airflow capacity. This measurement, therefore, plays an essential role in assessing respiratory health and guiding treatment plans.

The other options, while related to pulmonary function, do not accurately describe what FEV1 measures. Maximum oxygen consumption pertains to aerobic capacity; volume of air inhaled in one minute refers to the minute ventilation rate; and vital capacity encompasses the total volume of air that can be expelled after a deep breath, which is distinctly different from FEV1's specific focus on the first second of exhalation.