Lung Function Testing
Lung function testing (spirometry) measures how much air you exhale, and how quickly you exhale. It is an important tool to diagnose and understand asthma severity and control.
It may be used:
- During your first visit to evaluate your asthma
- After treatment has started and your symptoms have stabilized
- To document your best airway function
- At least once yearly to assess maintenance of airway function, regardless of medication or medication change
- To evaluate the response to a change in therapy
You will be instructed how to perform spirometry. Basically, you will take in a deep breath and blow into a mouthpiece attached to the spirometer and computer. You will blow out as hard and as fast as you can until your lungs feel absolutely empty. You will be asked to repeat the test several more times until there are two to three good efforts. You will be coached and encouraged to do your best during the test. A good effort during the test is important to get accurate results. Since the test involves some forced breathing and rapid breathing, you may have some temporary shortness of breath or lightheadedness.
The spirometry program on the computer calculates and graphs the results. The results demonstrate a person's air flow rates or the volume forced out within the first second. This is the Forced Expiratory Volume in the first second (FEV1). This indicates whether or not there is airway obstruction. Spirometry also records the total volume of air forced out of the lungs. This is the Forced Vital Capacity (FVC). The percentage of the FVC exhaled in the first second (FEV1) is also calculated with spirometry. This is the FEV1/FVC. While these are the main results we look at, there is other information to be gained through spirometry. We will review the spirometry results, discuss these in clinic with you and determine the best treatment for you.