How to prepare for
a spirometry test You can do a number
of things to make sure you’ll be able to breathe comfortably and receive an
accurate result during your spirometry test.
Wear loose clothing.
If you smoke, avoid smoking for at least 1
hour before the test.
If you drink alcohol, avoid consuming it for
at least 4 hours before the test.
Avoid eating or drinking for at least 2 hours
before the test.
Avoid heavy physical effort or exercise for at
least 30 minutes before the test.
Check with a healthcare professional about
whether you should avoid are any medications, such as inhalers, before the
test, since they may interfere with the accuracy of the results.
Spirometry
procedure A spirometry test usually takes about 15 minutes and
generally happens in your doctor’s office. In some cases when more in-depth
tests are necessary, they may take place at a respiratory laboratory. Here’s what happens during a spirometry procedure: 1. You’ll sit in a chair in an exam room
at your doctor’s office. The doctor or a nurse will place a clip on your nose
to keep both nostrils closed. They’ll also place a cup-like breathing mask
around your mouth. 2.Your doctor or nurse will next
instruct you to take a deep breath in, hold your breath for a few seconds, and
then exhale as hard as you can into the breathing mask. 3.You’ll repeat this test at least
three times to make sure that your results are consistent, especially if there
is a lot of variation between your test results. They’ll take the highest value
from three close test readings and use it as your final result. Your entire
appointment should last about 30 to 90 minutes. If you have evidence of a breathing disorder, your doctor
might then give you an inhaled medication known as a bronchodilator to open up
your lungs after the first round of tests. They’ll then ask you to wait 15 minutes before doing
another set of measurements. Afterward, your doctor will compare the results of
the two measurements to see whether the bronchodilator helped increase your
airflow. When used to monitor breathing disorders, a spirometry
test is typically done once
every 1 or 2 years to monitor changes in breathing in people
with well-controlled COPD or asthma. Those with more severe breathing concerns or breathing
complications that aren’t well managed are advised to have more frequent
spirometry tests. Spirometry side effects Few complications typically occur during or after a
spirometry test. However, you may want to be aware of the following. You may feel a bit dizzy or have some shortness of breath
immediately after performing the test, according to the American
Thoracic Society. In this case, stop immediately and tell your
doctor. In very rare cases, the test may trigger severe breathing problems. When you do this test, it will increase the pressure in
your head, chest, stomach, and eyes as you breathe out. So, it is unsafe if
you have heart problems or hypertension, or if you’ve had surgery on your
chest, abdomen, head, or eyes. Risks after a spirometry test There are a few risks related to the spirometry test itself.
However, there is a minor risk that you may get an indirect infection. This could happen in several ways:
Although there is no data widely available on
spirometer disinfection, there is potentially a concern that if the
spirometer tubing is not disinfected correctly after each test, people may
be at risk of infections by a variety of fungi microorganisms. These
include respiratory illnesses such as influenza, measles, chicken pox,
pneumonia, and tuberculosis. According to a 2015 research review trusted Source, researchers in
at least one study found bacterial growth on spirometer tubing.
Other equipment pieces, such as the breathing
valve and mouthpiece, may also transmit infection. It should be
disinfected and replaced between patients. In addition, you may want to be
careful about the laboratory infrastructure — the chair you’re sitting on,
nearby tables and surface areas, and anything else you may come into
contact with. Use hand sanitizer liberally and wash your hands after the
test. This may also help protect you against the coronavirus that causes
COVID-19 and other viruses.
Since spirometry involves breathing
aerosolized particles, there’s a risk of spreading airborne viral
illnesses. This risk applies both to the medical staff and to patients who
may be breathing in the air were a previous patient was present. While a
variety of illnesses can spread through the air, the gravest concern at
present is the coronavirus that causes COVID-19. Speak with your doctor
before your test if you think you may have symptoms of COVID-19Trusted
Source.
People with cystic fibrosis require more
frequent lung function tests. However, they are also at a higher risk of
infections in the upper respiratory tract from contact with equipment
related to the test and the personnel performing the test.
This risk may be higher in different countries, where
there are other standards and protocols for preventing the spread of infection. The American Thoracic Society and the European Respiratory
Society have
official technical standards for conducting spirometry. These
include disinfection guidelines and recommend disposable mouthpieces with
filters to avoid infections. Spirometry “normal” values and how to read your test
results “Normal” results for a spirometry test vary from person to
person. They’re based on your: (age/height/race/sex)
Your doctor calculates the predicted “normal” value for
you before you do the test. Once you’ve done the test, they look at your test
score and compare that value to the predicted score. Your result is considered
“normal” if your score is 80 percent or
more of the predicted value. Spirometry measures two key factors: expiratory forced
vital capacity (FVC) and forced expiratory volume in one second (FEV1). Your
doctor also looks at these as a combined number known as the FEV1/FVC ratio. If you have obstructed airways, the amount of air you’re
able to quickly blow out of your lungs will be reduced. This translates to a
lower FEV1 and FEV1/FVC ratio. FVC measurement One of the primary spirometry measurements is FVC, which
is the greatest total amount of air you can forcefully breathe out after
breathing in as deeply as possible. If your FVC is lower than expected,
something is restricting your breathing. “Normal” or “abnormal” results are
evaluated differently between adults and children. For children ages 5 to 18:
Percentage of predicted FVC value
Result
80%
or greater
normal
less than 80%
abnormal
For adults:
FVC
Result
is
greater than or equal to the lower limit of normal
normal
is less than the lower limit of normal
abnormal
An “abnormal” FVC could be due to restrictive or
obstructive lung disease, and other types of spirometry measurements are
required to determine which type of lung disease is present. An obstructive or restrictive lung disease could be
present by itself, but it’s also possible to have a mixture of these two types
at the same time. FEV1 measurement The second key spirometry measurement is FEV1. This is the
amount of air you can force out of your lungs in 1 second. It can help your doctor evaluate the severity of your
breathing issues. An FEV1 reading that’s lower than expected shows you might
have a significant breathing obstruction. Your doctor will use your FEV1 measurement to grade how
severe any breathing concerns are. The following chart outlines what’s considered
“normal” and “abnormal” when it comes to your FEV1 spirometry test results,
according to guidelines from the American Thoracic
Society:
Percentage of predicted FEV1 value
Result
80%
or greater
normal
70%–79%
mildly abnormal
60%–69%
moderately
abnormal
50%–59%
moderate to severely abnormal
35%–49%
severely
abnormal less
less than 35%
very severely abnormal
FEV1/FVC ratio Doctors often analyze the FVC and FEV1 separately, then
calculate your FEV1/FVC ratio. The FEV1/FVC ratio is a number that represents
the percentage of your lung capacity you’re able to exhale in 1 second. In the absence of restrictive lung disease that causes a
normal or elevated FEV1/FVC ratio, the higher the percentage gotten from your
FEV1/FVC ratio means the healthier your lungs are. A low ratio suggests
that something is blocking your airways. Here’s what’s considered a low ratio:
Age
Low FEV1/FVC ratio
5
to 18 years old
less
than 85%
adults
less than 70%
Next steps If your doctor finds that your results fall into the
“abnormal” category, they’ll likely perform other tests to determine whether
your impaired breathing is caused by a breathing disorder. These could include chest X-rays, sinus X-rays, and blood tests. The primary lung conditions that will cause unexpected
spirometry results include obstructive diseases such as asthma and COPD and restrictive
diseases such as interstitial pulmonary fibrosis. Your doctor may also screen for conditions that commonly
occur together with breathing disorders that can make your symptoms worse.
These include heartburn, hay fever, and sinusitis.
