What is Spirometry?
Spirometry is a simple and painless breathing test that helps assess how well your lungs are working.
During the test, you breathe into a mouthpiece connected to a device called a spirometer. After taking a deep breath, you will be asked to blow out as fast, hard, and completely as possible. The device measures how much air you can breathe out and how quickly you can expel it.
Spirometry is commonly used to assess conditions such as asthma, chronic obstructive pulmonary disease (COPD), and other respiratory problems. It can also be used to monitor an existing lung condition and evaluate response to treatment.
An Important Test for Understanding Breathing Problems
Your doctor may recommend spirometry to determine whether your symptoms are related to a lung or airway problem, assess how well a known condition is controlled, and monitor how effectively treatment is working.
Asthma Assessment
Spirometry can help identify airflow obstruction and assess whether airflow improves after using a bronchodilator inhaler.
COPD Assessment & Monitoring
It is an important test for evaluating COPD in people with persistent cough, breathlessness, or relevant risk factors, and for monitoring the condition over time.
Investigating Breathlessness
It can help determine whether symptoms such as persistent cough, shortness of breath, wheezing, or chest tightness are associated with impaired lung function.
Monitoring Treatment
If you already have a lung condition, repeat spirometry may help your doctor monitor changes and assess how well treatment is working.
Preoperative Assessment
In selected patients, spirometry may be used before surgery to assess respiratory function and help with perioperative planning.
Planning Further Tests
The results may help your doctor decide whether additional lung function testing or other investigations are needed.
Two Key Measurements — FEV1 & FVC
FVC (Forced Vital Capacity) is the total amount of air you can forcefully breathe out after taking the deepest possible breath. FEV1 (Forced Expiratory Volume in One Second) is the amount of air you can force out during the first second of that breath. Your doctor interprets these measurements, including the FEV1/FVC ratio, against appropriate reference values while considering factors such as age, height, symptoms, and clinical history.
What Happens During the Test?
You will usually perform the same breathing manoeuvre several times so that reliable and consistent measurements can be obtained. A trained healthcare professional will guide you through each step.
Initial Preparation
Your height and other relevant information may be recorded, and you may be asked about recent illness, medications, and medical history to make sure the test is appropriate for you.
Mouthpiece & Nose Clip
You will usually sit upright and place the spirometer mouthpiece in your mouth. A soft nose clip may be used to prevent air from escaping through your nose.
Deep Breath & Forceful Blow
You take the deepest breath possible, seal your lips firmly around the mouthpiece, and then blow out as fast, hard, and completely as you can.
Repeat for Reliable Results
The manoeuvre is repeated several times to make sure the measurements are consistent and technically acceptable. You can rest between attempts if needed.
The Test May Be Repeated After an Inhaler
In some cases, after the first spirometry test you may be given a bronchodilator medicine to help open the airways. After waiting for the medicine to take effect, spirometry is repeated. Comparing the measurements before and after the bronchodilator helps your doctor assess whether airflow improves significantly, which can provide useful information when evaluating asthma and other airway conditions.
Simple Steps for More Reliable Results
Always follow the specific instructions provided by your doctor or testing centre. In particular, do not stop an inhaler or other medication unless you have been specifically instructed to do so.
Avoid Smoking
Avoid smoking or vaping before the test. Follow your testing centre’s instructions about how long you should avoid them beforehand.
Avoid a Heavy Meal
It is generally helpful to avoid a large or heavy meal for about two hours before testing, as a full stomach may make deep breathing more difficult.
Wear Comfortable Clothing
Wear loose, comfortable clothing that does not restrict expansion of your chest or abdomen. Avoid strenuous exercise shortly before the test.
Ask About Your Inhalers
Some tests require certain inhalers to be withheld temporarily. Only change your usual inhaler or medication schedule when instructed by your healthcare team.
It Is Not Just One Number — The Overall Pattern Matters
Spirometry is interpreted using measurements such as FEV1, FVC, and the FEV1/FVC ratio, together with test quality, symptoms, and medical history. The pattern can provide important information about airflow obstruction. Some abnormal patterns, however, may require additional lung function tests before a specific physiological abnormality can be confirmed.
What Should You Tell the Testing Team?
Tell your healthcare team if you currently have or recently had a chest infection, or if you have had a recent heart attack, stroke, pneumothorax, aneurysm, coughing up blood, uncontrolled high blood pressure, or recent chest, abdominal, or eye surgery. Forceful breathing can occasionally cause temporary dizziness, coughing, or shortness of breath. The test can be paused if you feel unwell.
Spirometry is an Important Test of Lung Function
Spirometry is a quick, painless, and widely used lung function test. It provides valuable information when investigating breathing symptoms, assessing conditions such as asthma or COPD, monitoring response to treatment, and deciding whether further testing is needed. Following the healthcare professional’s instructions and giving your best effort during each breathing manoeuvre are essential for obtaining reliable results.