Which statement about spirometry is true?

• A. It measures blood oxygen
• B. It only measures inhaled volume
• C. It is used primarily in sleep studies
• D. It assesses how well your lungs work by measuring air volume and flow during inhalation and exhalation

Answer: (D)

Spirometry gauges how well the lungs work by tracking the amount of air you move and how fast you move it, during both inhalation and exhalation. This is why the statement describing spirometry as measuring air volume and flow during breathing fits true—it captures what the test actually does.

It’s not about blood oxygen levels—that’s measured with pulse oximetry or arterial blood gases. It’s not limited to inhaled volume either, since it records both how much air you inhale and exhale as well as the speed of that exhalation or inhalation. And while sleep studies focus on breathing during sleep, spirometry is a daytime lung-function test used to diagnose and monitor conditions like asthma and COPD, as well as to assess pre-surgical risk and guide treatment.

A typical result set includes metrics like how much air you can forcefully exhale in one second and the total exhaled air, which helps distinguish different kinds of lung problems.