How to perform a spirometry test
To perform spirometry the worker takes a deep breath in and blows out as fast and hard as he can into a mouthpiece attached to the spirometer until the lungs are absolutely empty, and then inhales again to fill the lungs completely. The test is repeated several times until there are three identical efforts which ensure results are accurate. The test is often repeated after giving a short acting bronchodilator to find out how the airways respond to this type of medication (bronchodilator responsiveness test).
Figure 1.2: Watch this video on how to do a spirometry test here:
Video: https://youtu.be/1-YpkHpk4oc
Figure 1.3:
https://upload.wikimedia.org/wikipedia/commons/8/8c/Vital_Capacity.png .
No author provided- assumed  StephaniegreenwoodÂ