Which statement about FVC and FEV1 is true?

Which statement about FVC and FEV1 is true?

• A. FVC equals the total air exhaled during a full maximal expiration.
• B. FEV1 is the volume exhaled in the first second.
• C. FVC measures the rate of airflow per second.
• D. FVC is the total volume exhaled during a maximal expiration; FEV1 is the volume exhaled in the first second.

Answer: (D)

The main idea here is understanding what FVC and FEV1 measure in spirometry. FVC is a volume: the total amount of air you can forcibly exhale after taking a deep breath in, reached by a maximal, forceful expiration. FEV1 is also a volume, specifically the amount exhaled in the first second of that same forced expiration. The statement that pairs both definitions—FVC as the total volume exhaled during a maximal expiration and FEV1 as the volume exhaled in the first second—is the most precise and accurate description. The other options are less precise or mix up concepts: one describes FVC without explicitly tying it to the forceful effort, another only defines FEV1 and omits FVC, and another confuses FVC with an airflow rate rather than a volume.

The main idea here is understanding what FVC and FEV1 measure in spirometry. FVC is a volume: the total amount of air you can forcibly exhale after taking a deep breath in, reached by a maximal, forceful expiration. FEV1 is also a volume, specifically the amount exhaled in the first second of that same forced expiration. The statement that pairs both definitions—FVC as the total volume exhaled during a maximal expiration and FEV1 as the volume exhaled in the first second—is the most precise and accurate description.

The other options are less precise or mix up concepts: one describes FVC without explicitly tying it to the forceful effort, another only defines FEV1 and omits FVC, and another confuses FVC with an airflow rate rather than a volume.