Spirometry

What is spirometry?

Spirometry is the gold standard to diagnose chronic obstructive pulmonary disease (COPD). It’s also used to measure the progression of the disease for people already diagnosed with COPD.This test is also sometimes called a “lung function test” or “pulmonary function test”.

 

Spirometry measures the volume of air that you can inhale and exhale. It’s used to diagnose both obstructive lung diseases (e.g., COPD, asthma, cystic fibrosis) and restrictive lung diseases (e.g., pulmonary fibrosis, muscular dystrophy).

 

It’s also used to help your doctor know if your condition is improving or worsening and whether your medication is working properly.

How it works?

If your doctor suspects that you may have a lung disease, you will be given a referral to have a spirometry test at a nearby hospital or clinic. Some doctors can even do the test right in their offices if they have the right equipment.

 

The test doesn’t hurt, doesn’t require any prep work, and is done while you are awake. You may feel tired afterwards from the breathing exercises, as though you’ve finished blowing up several balloons.

 

A spirometry test uses a small machine with a mouthpiece on it called a spirometer. The mouthpiece is attached to a tube, which feeds into the machine. A spirometer measures the amount of air you can inhale (breathe in) and exhale (breathe out), and the amount of time it takes to exhale completely after a deep breath.

Spirometry
<div class="title">Spirometry</div>

Before your test, you will be given a list of instructions. These instructions will tell you if you need to take or hold off on any medications or puffers. They may advise you not to smoke or drink alcohol close to the time of the test. You should also not exercise or eat a big meal right before the test.

 

During the test, you’ll be seated with a clip placed over your nose to stop air from escaping. You will then be asked to:

• Breathe into the mouthpiece, taking a big breath in and a big breath out.
• Exhale rapidly for at least 6 seconds, as fast as possible.

 

It is crucial to give your best effort on each breathing test for the most accurate results—these will help your healthcare team prescribe appropriate therapy.

You may also be given medications like a rescue puffer, or bronchodilator, and then repeat the test. Each breathing maneouver takes about 10 seconds and is done 3 to 6 times.

 

After the test, the results will be sent to your doctor. Depending on your results, your doctor may give you a diagnosis or prescribe therapies, exercises, or other treatments.

Understanding the results

Spirometry measures many different parts of your breathing cycle. Two key measurements to understand are FEV1 and FVC.

FEV1 stands for Forced Expiratory Volume in 1 second—how much air a person can exhale, or push out, in 1 second. This is measured in percentages.

FVC stands for Forced Vital Capacity—how much air a person can exhale, or push out, to the end of the breath.

 

The diagnosis of the severity of a person’s COPD are based, in part, on their FEV1. Not all lungs are the same and will differ based on age, gender, ethnicity, weight, and height. Spirometry results take all of these factors into account. There are values that are expected for each person and then these values are compared to their actual spirometry results.

The results of your spirometry test can be used in a variety of ways:

• They can show whether your lung condition is getting better, worse, or staying the same.

• The results can help guide decisions in treatment and medication.

 

Spirometry tests can sometimes be done before surgeries to determine whether it will be safe to proceed or if any extra steps need to be taken during surgery to ensure your safety.

Example of a spirometry with normal curve (healthy lungs)
Example of a spirometry with obstructive curve (could be COPD but also Asthma)
Example of a spirometry with obstructive curve (could be COPD but also Asthma)

This is an example of a spirometry test with an obstructive curve. If you have a lung condition that causes narrowed airways, such as COPD or asthma, it is common to have an obstructive pattern.

 

This means that air flows out of your lungs more slowly than normal (low FEV1) with less than 70% of the total amount in the first second.

 

People with COPD have an FEV1/FVC ratio below 70%. To determine the severity of your airflow obstruction, criteria such as these are used. Keep in mind that individuals with the same degree of airflow obstruction may have varying levels of breathlessness.

In recent years, there has been a push in Canada for more family physicians to conduct spirometry tests in their offices. Currently, however, most spirometry is still performed at specialty clinics and hospitals.

Want to know more?

Learn more about the 4 stages of COPD here.

FAQ

Frequently Asked Questions

Spirometry tests are safe when done in a medical environment with a health care professional. People may feel tired or lightheaded during or following the test because of the amount of breathing required—this is completely normal.

Some people should not have a spirometry test. People with recent eye or brain surgery, brain or aortic aneurysm, recent heart attack, heart failure, pregnancy, or active infection should likely not receive this test.

An appointment typically lasts 30 minutes, but most of that time will be spent learning from the health care professional how to do the test properly.

For those who have a lot of trouble breathing, spirometry tests can be hard to do since the test takes a lot of effort. It can be exhausting to breathe deeply and quickly for an extended period of time. You will be allowed to take breaks if needed. The more effort you can give the test, the more accurate the results will be.

At-home handheld spirometry tests are becoming more popular. But beware! Some at-home tests are good quality and some are not. Follow your doctor’s advice when it comes to the method used for taking the test to ensure that it’s done properly.

If you’re feeling sick on the day of your test, reschedule your appointment. Spirometry is based on breathing heavily, so people who are sick may spread bacteria or viruses during the test. Also, the results won’t reflect the usual state of your lungs. If you’re feeling unwell, cancel your appointment and reschedule when you’re fully recovered.

If you’re diagnosed with COPD, you may be asked to do a spirometry test every year to monitor your progress. Others with COPD may need to repeat the test more often if their symptoms change or worsen.