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Diagnostic tests · Saint‑HyacintheMESI technology
Spirometry: assessing your lung function
A simple test to better understand your breathing.
Spirometry is a lung function test that measures how much air you can breathe out and how fast you can breathe it out.
It can be used to document certain respiratory symptoms, help assess diseases such as asthma or chronic obstructive pulmonary disease (COPD), or monitor the course of a known respiratory condition.
At the Clinique IPS du Palais, spirometry is performed with MESI mTABLET SPIRO technology. Our team guides you throughout the test to help you perform the required breaths correctly.
Spirometry mainly measures the volumes and flows of air produced during a forced exhalation.
You take a deep breath in, then blow into a mouthpiece connected to the spirometer according to the instructions given by the professional. Several attempts are generally needed to obtain measurements that are sufficiently reproducible and interpretable.
It can help assess a person who has:
shortness of breath;
a persistent cough;
wheezing;
a feeling of chest tightness;
reduced exercise tolerance;
or recurrent respiratory symptoms.
The measurements
What does spirometry measure?
The results are compared with reference values that take relevant individual characteristics into account.
Interpretation therefore does not rely on a single number.
FVCForced vital capacity: the total amount of air forcefully exhaled after a maximal inhalation.3
FEV₁Forced expiratory volume in one second: the air exhaled during the first second.3
FEV₁/FVCThis ratio helps determine whether airflow is reduced in a way consistent with airway obstruction.
Respiratory diseases
Spirometry and asthma
Asthma is characterized by, among other things, variable airway obstruction. Spirometry can help demonstrate this obstruction and check whether it improves after a bronchodilator is given.
A Canadian quality standard on asthma (Ontario Health, 2025) describes spirometry as the preferred lung function test for diagnosing asthma, by assessing obstruction and its reversibility.2
However, normal spirometry does not automatically rule out asthma, especially when asthma is well controlled.2 Other investigations may then be needed.
Spirometry plays a central role in diagnosing chronic obstructive pulmonary disease (COPD).
INESSS emphasizes the importance of analyzing and interpreting spirometry results in establishing a diagnosis of COPD. In September 2026, it published a Quebec spirometry interpretation tool to support this diagnosis.1
For COPD, interpretation takes into account the measurements obtained after a bronchodilator and the clinical context. The presence of respiratory symptoms alone is not enough to confirm COPD.
In some situations, spirometry is performed in two stages.
1
Pre-bronchodilator measurement
A first series of manoeuvres measures baseline lung function.
2
Administration of a bronchodilator
When indicated, a medication that helps open the airways is given.
3
Post-bronchodilator measurement
After the appropriate waiting time, spirometry is repeated. The comparison provides information on the reversibility of airway obstruction.
Do all tests include a bronchodilator? No. It depends on the reason for the test, the prescription or clinical request, the protocol used and your situation. Spirometry alone and pre/post-bronchodilator spirometry do not necessarily answer the same clinical question.
Preparation
How to prepare properly?
Good preparation helps obtain results that reflect your lung function. Unless otherwise instructed by the professional requesting the test, the Canadian Lung Association recommends, among other things:3
You do not need to fast.
do not smoke for at least 1 hour before the test;
avoid alcohol in the previous 4 hours;
avoid a large meal in the previous 2 hours;
avoid intense exercise for at least 30 minutes before the test;
wear loose, comfortable clothing;
bring an up-to-date list of your medications, especially your inhalers or “puffers”.
Should I stop my inhalers before spirometry?
Do not stop your medication on your own.
Depending on the purpose of the test, some inhalers may need to be stopped for a few hours before spirometry.3 In other situations, the professional may want to assess your lung function while you are taking your usual treatment. The length of time also varies depending on the medication.
Instructions are determined at the time of booking or by the professional requesting the test. If you have not received any instructions, contact our team before changing your medication.
When should you notify us before your test?
Inform our team if your health has recently changed, especially if you have had:
recent respiratory infection;
significant worsening of your shortness of breath;
chest pain;
recent surgery;
recent cardiovascular event;
significant dizziness;
or any situation that could make a forced exhalation difficult or risky.
The professional will be able to determine whether the test can be done right away or whether it is better to postpone it.
What to bring
What should you bring to the appointment?
Previous results can be particularly useful for comparing changes in your lung function.
When available:
your prescription or test request;
your list of medications;
your inhalers;
results of previous spirometry tests;
results of other relevant respiratory tests;
and the contact information of the professional who requested the test.
Your appointment
How is spirometry performed?
1
Explanation of the test
The professional explains the manoeuvre to you. The quality of the result depends in part on the effort made and on understanding the instructions properly.
2
Positioning
You sit up straight with both feet on the floor.4 A nose clip may be used to prevent air from escaping through the nose.
3
Maximal inhalation
You take the deepest breath possible to fill your lungs completely.
4
Fast, sustained exhalation
With your lips around the mouthpiece, you blow as hard, as fast and as long as possible, with encouragement from the professional.
5
Repetition
The manoeuvre is repeated to obtain reproducible attempts: at least 3, and normally no more than 8.4
Good to know
Why do you have to repeat it several times?
An attempt can be affected by an incomplete inhalation, a start that is too slow, a leak around the mouthpiece, a cough, stopping too soon or insufficient effort.
Repeating an attempt does not mean that a lung problem is present.
Because the exhalation is very forceful, you may temporarily feel tired, short of breath, dizzy, have an urge to cough or feel light-headed. The professional stays with you and can stop the manoeuvre.
How long does the test take?
The length depends on the number of attempts needed, the quality of the first measurements and whether or not a bronchodilator test is performed.
Pre/post-bronchodilator spirometry takes longer, because a waiting period must be observed between the medication and the new measurements.
Our technology
Digital, guided spirometry
At Clinique IPS du Palais, we use the MESI mTABLET SPIRO.
During the manoeuvre, the flow-volume curve and the parameters are displayed on the screen. If no quality issue is detected, a green check mark appears, and the device analyzes the exhalations to automatically select the best curve.5
At the clinic, single-use mouthpieces and filters are used with the MESI system, in accordance with the device’s requirements.
Curve displayed in real time
Quality control of attempts
Single-use mouthpieces
Interpretation
How are the results interpreted?
Results are not interpreted solely by looking at whether a value is “high” or “low.”
When a pre/post-bronchodilator test is performed, the response to the bronchodilator is also considered.
The analysis takes into account, among other things:
FEV₁, FVC and the FEV₁/FVC ratio;
the quality of the manoeuvres;
reference values, age and height;
symptoms and medical history;
exposure to tobacco or other substances;
and other clinical information.
Does abnormal spirometry give a diagnosis?
No. It provides objective data on respiratory function, but the diagnosis is based on the overall context: symptoms, medical history, clinical examination, risk factors and sometimes other tests.
Likewise, normal spirometry does not rule out all respiratory diseases.
Spirometry or chest X-ray?
Spirometry assesses how the lungs work, mainly air volumes and flows. An X-ray produces an image of the chest.
One does not replace the other; depending on the symptoms, they may be complementary.
Spirometry or pulse oximetry?
Pulse oximetry mainly measures the oxygen carried in the blood using a finger sensor. Spirometry measures the amount and speed of exhaled air.
A normal oxygen saturation therefore does not rule out an abnormality on spirometry.
Frequently asked questions
Frequently asked questions
Do I need to fast?
No. However, it is recommended to avoid a very large meal in the two hours before the test.
Can I have my coffee?
Instructions may vary depending on the context of the test. Follow the instructions given when booking if special preparation is required.
Can I smoke beforehand?
The Canadian Lung Association recommends not smoking for at least one hour before spirometry.
Should I stop my puffers?
Only if you have been asked to. Never change your respiratory treatment without specific instructions.
Will I have to blow several times?
Yes. Several manoeuvres are generally needed to obtain reliable and reproducible results.
Can spirometry be done when you are sick?
It depends on the situation. A respiratory infection or a significant worsening of symptoms can alter the results or make the test less appropriate at that time. Contact the clinic before your appointment if your condition has changed.
Can I have the test with an outside prescription?
Yes, depending on the request and the terms of the service. Bring your prescription to the appointment.
Is the interpretation included?
It depends on the service chosen. At the Clinique IPS du Palais, spirometry alone and spirometry with clinical interpretation are offered as separate services.
Fees
Spirometry at Clinique IPS du Palais
Clinique IPS du Palais offers spirometry in Saint-Hyacinthe with MESI mTABLET SPIRO technology.
Spirometry
125 $
Measurement of respiratory volumes and flows using the MESI spirometer. Our team explains the manoeuvres and guides you to obtain usable measurements.
Spirometry with interpretation
195 $
Includes performing the spirometry, analyzing the results and an interpretation report by our primary care nurse practitioner (PHCNP), to guide the next steps of your follow-up.
Before your appointment: do not stop an inhaler or any other medication without instructions from the professional responsible for your test. If you have had a recent respiratory infection or if your condition has worsened, contact the clinic before coming in.
Do you have a prescription for spirometry?
Our team can inform you about the type of test requested, the preparation instructions and how the interpretation is done.
Spirometry may also be ordered by our NPs when it is relevant to your clinical assessment.
Institut national d’excellence en santé et en services sociaux (INESSS). Maladie pulmonaire obstructive chronique (spirometry interpretation tool and national medical protocols). September 2026, accessed October 5, 2026. inesss.qc.ca
Ontario Health. Asthma: Care in the Community for People 16 Years of Age and Older — 2025 Update (quality standard). June 2025, accessed October 5, 2026. cts-sct.ca
Canadian Lung Association. Spirometry. Modified May 20, 2026, accessed October 5, 2026. lung.ca
MESI. How to conduct a spirometry measurement. Undated, accessed October 5, 2026. mesimedical.com
MESI. Outils automatiques en spirométrie. February 20, 2024, modified December 22, 2025, accessed October 5, 2026. mesimedical.com
The information on this page is provided for informational purposes and does not replace an assessment by a health professional.
