Spirometry Testing Explained
Spirometry Testing Simplified
> As & Bs vs. Cs & Ds
> 80.0% OR BETTER (FEV) - What does it really mean and how do we make it happen?
What is it?
So what exactly is the Spirometry Test and why is it so important to test it each year? In short; the Spirometry test is a minimally invasive and short duration test that utilizes a person’s age, ethnicity, gender, height, and weight to predict their lung capacity according to how other people in those categories perform. Predict is the key word because an abnormal performance doesn't necessarily mean that something is wrong a person. It could be that they're built slightly different than others.
What does it look like?
We start by entering a person’s information so that the device can set the standards that need to be met by that individual. After that we are ready to begin with each of the “trials”.
A trial is performed by inhaling deeply, inserting the tube into your mouth, and then forcefully exhaling the air in your lungs through the tube and sustaining that exhaled breath until the test stops. This can be an uncomfortable sensation when there is no resistance on the other end and can leave someone feeling like there is nothing left to push out. Even then we still ask you to keep pushing, breathing, and squeezing your core to ensure the test isn’t stopped too soon. The reason this is possible is because of how sensitive the device actually is. Even if you don’t feel like you’re moving air through the tube it could still be picking up enough movement to register for the test.
What do the letter grades (A,B,C,D) mean?
Everyone who takes the test is required to perform a minimum of THREE breaths to officially pass the test. Even if you gave a perfect trial you would be required to do three breaths in order to achieve the (A) or (B) score needed. This letter grade refers to the person’s ability to repeat the breath consistently. For example: if you did three perfect (A) tests in a row; the first test is the baseline and would show a session quality of “D”. The second perfect test might show a session quality of “C” because the device can compare it to the first one. The third test would be the first time you’d ever see the actual “A” or “B” score once you’ve proven you can repeat the trial multiple times. So, make sure you don’t think of these letter grades the same way you would with a school test. If you kept changing your technique because you think it’ll make the letter grade better, you’ll actually be getting further and further away from proving that you can repeat the same breath multiple times in a row.
*Note: Many people will perform more than three breaths to pass the test. They might perform four tests if the first three are so unique that they all register as a “D”. However, a fourth test might come back as an “A” or “B” if it’s close enough to one of the previous trials. This idea can continue on depending on a person’s ability to be consistent with each trial*
What do the graphs mean?
When we perform the test we see two graphs. Yellow and Purple.
The Yellow line represents the “Air FLOW” of your breath when you forcefully exhale. The shape will show the rate (speed) of air going through the tube and will spike higher or lower based on the amount of force you put into each trial.
The Purple line represents the “Air VOLUME” and this is the number required to meet a minimum standard of 80.0% or better. This line shows the amount of air that you’re actually pushing through the tube and is based on how big of a breath you take before you start the trial. Meeting the 80% minimum standard is essentially saying “You need to move at LEAST 80% of the volume of air through the tube in the FIRST second of the test based on what the test expects you to do.”
Being nervous and taking a shallow breath could potentially make this score lower. It’s also important to know that Faster FLOW does not always equal More VOLUME. Pushing too fast and losing “speed” before you make it to the 1-second line can actually lower your “volume” score and that’s the number we want to keep above 80%. The goal is to use moderate force at the beginning of the test so that you can extend your breath all the way through the first second line of the test.