Lung Function Tests To Monitor Asthma

If you've ever experienced shortness of breath, chest tightness, wheezing, or coughing, you know how uncomfortable and worrisome these symptoms can be. Making an appointment with your healthcare provider is the best way to determine if asthma or another health condition is to blame.

In most cases, diagnosing asthma will include undergoing one or more lung function tests. Here's what you should know about which lung function tests are used to diagnose and monitor asthma and how they can help form a treatment plan.

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Who can get asthma?

Asthma¹ is a chronic respiratory condition affecting the tubes that carry air in and out of your lungs. For individuals diagnosed with asthma, these airways can become inflamed or constricted due to certain triggers, making it difficult for air to travel back and forth from your lungs as it should. The Centers for Disease Control and Prevention (CDC)² estimates that as many as 1 in 13 people in the US have asthma. 

Asthma affects people of all ages but often develops during childhood. Unfortunately, there is no cure for asthma. However, working closely with your healthcare provider to create an asthma action plan³ catered to your specific needs can help keep your symptoms under control.

What is an asthma attack?

Asthma attacks occur when the airways that lead to your lungs become inflamed and swollen. As a result, the muscles surrounding these airways contract. The airways create an overproduction of mucus, which causes your breathing tubes to constrict. 

An asthma attack comes with symptoms ranging from minor to life-threatening, including coughing, wheezing, and difficulty breathing. The best way to get an asthma attack under control is to recognize its symptoms as early as possible and seek immediate treatment before it progresses and becomes more difficult to stop.

Asthma attacks are most often brought on by exposure to specific triggers. While different factors will trigger every person with asthma, some common irritants are known to contribute to asthma symptoms when inhaled. These include:

  • Pollen

  • Pet dander

  • Cold air

  • Cigarette smoke

  • Viruses

  • Mold

  • Cockroaches

  • Dust Mites

  • Exercise

  • Certain medications

Paying attention to which triggers cause asthma symptoms for you is important. Be sure to note when you experience asthma symptoms and what might be the cause, such as exercise, breathing in cigarette smoke, or cold weather. Then let your healthcare provider know what your suspected triggers are. 

Together, you and your doctor can devise a personalized treatment plan to manage and prevent asthma flare-ups from occurring in the future. This could include taking asthma medications to prevent or manage symptoms, making lifestyle changes, such as wearing something over your face when going outside in cold weather, and avoiding triggers when possible. 

What are Pulmonary Function Tests (PFTs)?

Pulmonary Function Tests⁴ (PFTs), also known as lung function tests, are noninvasive screenings typically performed at your healthcare provider's office to see how well your lungs are functioning. These tests can measure various factors, including your lung volume, capacity, rates of airflow, and gas exchange. The results of lung function tests are useful in helping your doctor diagnose the cause of your symptoms and provide an individualized treatment plan. 

What are the different lung function tests for asthma?

Different lung function tests can be used to diagnose and monitor asthma. These include:

  • Spirometry test

  • Peak flow test

  • Challenge test

  • Exhaled nitric oxide test

Spirometry tests and peak flow tests are typically the ones that healthcare providers use to determine if a person's symptoms are caused by asthma. Both tests are quick, painless, and effective at determining lung function. 

Spirometry tests use a device called a spirometer. The device consists of a mouthpiece attached to a small electronic machine. A peak flow test requires you to breathe into another small machine called a peak flow meter. It's normal for the results of these tests to vary from person to person. 

Your test results will be compared to the average of a person of the same age, weight, height, and race, along with any previous test results that you may have. Additional testing may be required if your test results are abnormal or have changed since your last test. 

What happens during a spirometry test?

If your healthcare provider decides you are a good candidate for a spirometry test, they will instruct you on the specifics. 

First, you will put your mouth on the spirometer, take a deep breath, and blow out as hard as you can until your lungs feel empty. You may be asked to do this several times until your provider has received two or three good readings. Doing the best you can is important to demonstrate the capability and health of your lungs.

Your results will be recorded, displaying your airflow rates or volume of air forced out within the first second, also known as the Forced Expiratory Volume (FEV1). This number will let your doctor know if anything is obstructing your airway.

The spirometry test will also record the total volume of air forced out of your lungs, also known as the Forced Vital Capacity (FVC). The spirometer will calculate the percentage of your FVC exhaled in the first second (FEV1). 

The results of your FEV1/FVC and any improvement after bronchodilator treatment will help your healthcare provider determine the best treatment options for your circumstances. 

Why test my lung function?

Performing lung function testing is critical in diagnosing and managing asthma, along with demonstrating how your lungs behave in response to asthma medications. 

These tests are important because asthma symptoms, such as coughing, wheezing, and shortness of breath can also be attributed to other health conditions.

Along with discussing your symptoms, family history, and other medical conditions, a lung function test is one of the most effective tools to diagnose asthma. In most cases, lung function tests are appropriate for adults and children over five but are hard to perform in children under five.

Because asthma symptoms can change over time and in response to different triggers, it may be necessary to have a lung function test performed more than once.

If your healthcare provider diagnoses you with asthma after performing a lung function test, they will likely test your lung function four to six weeks after being prescribed medication to see if your symptoms have improved or if another treatment option should be explored.

How do I know if I need a lung function test?

If you are experiencing asthma symptoms, don't wait to schedule an appointment with your healthcare provider. They will determine whether or not a lung function test is an appropriate option for you. 

They will likely make this decision based on the symptoms you're experiencing, such as:

  • Wheezing

  • Coughing

  • Shortness of breath

  • Chest tightness

While these are common symptoms, assuming that asthma is the cause without performing a lung function test is never a good idea. By skipping a lung function test, you could be given asthma medications you don't need. Furthermore, the true cause of your asthma-like symptoms would not be treated properly.

How do I prepare for a lung function test?

Your healthcare provider will let you know of any necessary steps that you should take before undergoing a lung function test. If you have been prescribed any medications to relax your airways, such as bronchodilators, they may ask you to stop taking them before your test.

It's also a good idea to stop smoking for 24 hours before the test, as well as avoid exercise, eating large meals, and consuming alcohol in the hours leading up to your lung function test. Lastly, be sure to wear comfortable and loose-fitting clothes to your appointment.

The lowdown

Asthma is a long-term condition that affects as many as 1 in every 13 Americans. Asthmatics may experience symptoms such as coughing, wheezing, and shortness of breath when exposed to certain triggers, such as pet dander or cold weather. 

Lung function tests, such as spirometry tests, play an important role in helping diagnose and manage asthma in adults and children over five. These noninvasive tests can let your healthcare provider know how well your lungs are functioning and identify if you may have asthma. They are also useful in identifying the effectiveness of an existing asthma treatment plan.

  1. What is asthma? | NIH: National Heart, Lung, and Blood Institute

  2. Most recent national asthma data | Centers for Disease Control and Prevention (CDC)

  3. Treatment and action plan | NIH: National Heart, Lung, and Blood Institute

  4. Pulmonary function tests | Johns Hopkins Medicine

Other sources:

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