What is forced expiratory volume in 1 second (FEV1)?

What is forced expiratory volume in 1 second (FEV1)?

• A. The volume of air forcibly expired in the first second of a maximal expiration.
• B. The total volume exhaled after a full inhalation.
• C. The amount of air left in the lungs after a forced expiration.
• D. The volume of air forcibly inhaled in the first second of a maximal inhalation.

Answer: (A)

FEV1 is the amount of air you can forcibly exhale in the first second of a maximal expiration. It shows how quickly air can be moved out of the lungs and reflects the caliber of the airways and expiratory flow. This measurement comes from spirometry and is most informative when interpreted together with the forced vital capacity, which is the total volume exhaled during a full forced breath, to give the FEV1/FVC ratio. The other options describe different lung volumes: the total exhaled volume is FVC, the air left after expiration is residual volume, and the volume inhaled in the first second of a maximal inhalation is an inspiratory measure, not expiratory.

FEV1 is the amount of air you can forcibly exhale in the first second of a maximal expiration. It shows how quickly air can be moved out of the lungs and reflects the caliber of the airways and expiratory flow. This measurement comes from spirometry and is most informative when interpreted together with the forced vital capacity, which is the total volume exhaled during a full forced breath, to give the FEV1/FVC ratio. The other options describe different lung volumes: the total exhaled volume is FVC, the air left after expiration is residual volume, and the volume inhaled in the first second of a maximal inhalation is an inspiratory measure, not expiratory.