Asthma and Lung Function

The Facts about Asthma and Lung Function

While reduced lung functioning often isn't visible to the eye or ear, it's an important measure that tells your doctor what to expect, both when you're well and also when you're sick. That's why many doctors rely on a tool called a spirometer, which measures your pulmonary functioning and lets you know when a problem exists.

Measuring Asthma and Lung Function

When your doctor performs a spirometry test, he'll ask you to take a breath and then blow it out into a special tube as hard as you can. The spirometer instrument will measure how much air is left in your lungs. Often one batch of results isn't enough to make a complete diagnosis, though. In order to fully understand your overall lung functioning, your doctor may need to do some comparison tests. To this end, he should ask you to use your fast-acting relief inhaler first, then to repeat the breathing test. If the results change a great deal with the help of the inhaler, this tells him that you likely have asthma, which is preventing your lungs from working up to their full potential. If your lung function isn't up to par, your doctor may help you to identify and eliminate exposure to any possible triggers that could be negatively affecting your breathing. He will also give you medications to help control your condition.

Low Lung Capacity

Just keep in mind that while your lung capacity will be compromised during an asthma attack, some asthmatics also find that their overall lung functioning is reduced even when their symptoms are well controlled. This means that they have a lower lung capacity to start with, so when an attack occurs, their capacity and functioning can decline even more, putting them at even greater risk.


When it comes to assessing asthma and lung function, in addition to how well your lungs work, how responsive your airways are can also be very indicative of your overall health situation. For instance, if your lungs are hyper-responsive to change, you need to be especially concerned. In such a scenario, you may find your lung capacity is reduced suddenly as the result of being exposed to a trigger. It may also dramatically improve right away when you use your fast-acting relief inhaler. This roller coaster response should serve as a warning that your lungs could go from very good to very bad in only a few seconds, which means that you could be at risk for having a sudden life threatening attack. Therefore, you'll need to be extra vigilant about following your asthma action plan.

A Final Note

By paying attention to your asthma and lung function, you can better understand your health and learn how best to treat your condition and head off your risks of serious complications before they begin.




National Sleep Foundation

University of Chicago Medical School