Spirometry: procedure, "normal" values ​​and test results (2023)

Spirometry is a standard test that doctors use to measure how well your lungs are working. The test measures the flow of air into and out of the lungs.

To take a spirometry test, you sit and breathe into a small machine called a spirometer. This medical device records the amount of air inhaled and exhaled, as well as the respiratory rate.

Doctors use spirometry tests to do this.to diagnosethese conditions:

  • COPD
  • Asma
  • restrictive lung disease, such as interstitial lung fibrosis
  • other diseases that affect lung function

They also allow your doctor to monitor chronic lung conditions to see if your current treatment is improving your breathing.

Spirometry is often performed as part of a group of tests known aslung function tests.

There are a number of things you can do to ensure you can breathe comfortably and get an accurate result during your spirometry test.

Consider these tips:

  • Wear loose clothing.
  • If you smoke, please refrain from smoking for at least 1 hour before the test.
  • If you drink alcohol, refrain from drinking at least 4 hours before the test.
  • Avoid eating or drinking for at least 2 hours before the test.
  • Avoid heavy physical exertion or exercise for at least 30 minutes before the test.
  • Check with a doctor about avoiding medications like inhalers before the test, as they can affect the accuracy of the results.

A spirometry test usually takes about 15 minutes and is usually performed in your doctor's office. In some cases where more in-depth tests are needed, they can be done in a respiratory laboratory.

(Video) Spirometry Results Explained

Here's what happens during a spirometry procedure:

  1. You are sitting in a chair in an exam room at your doctor's office. The doctor or nurse will place a nose clip to keep both nostrils closed. They also place a cup-shaped breathing mask around their mouth.
  2. Then your doctor or nurse will instruct you to take a deep breath, hold your breath for a few seconds, and exhale as hard as you can into the respirator.
  3. You will repeat this test at least three times to ensure that your results are consistent, especially if there are large differences between your test results. You take the highest value from three close test readings and use that as the final result. Your entire engagement should last approximately 30 to 90 minutes.

If you have signs of a breathing disorder, your doctor may give you an inhaled drug known as a bronchodilator to open up your lungs after the first round of tests.

They will then ask you to wait 15 minutes before taking another series of measurements. Your doctor will then compare the results of the two measurements to determine whether the bronchodilator helped to increase your airflow.

When monitoring breathing disorders, a spirometry test is typically performedonce every 1 or 2 yearsto monitor respiratory changes in people with well-controlled COPD or asthma.

Those with more severe breathing difficulties or breathing complications that are not well controlled are advised to have spirometry tests more frequently.

There are usually few complications during or after a spirometry test. However, please note the following.

As a result, you may feel slightly dizzy or short of breath immediately after taking the test.American Thoracic Society🇧🇷 If this happens, stop immediately and tell your doctor. In very rare cases, the test can cause severe breathing problems.

When you do this test, the pressure in your head, chest, abdomen, and eyes increases as you exhale. That's how it isinsecureif you have heart problems or high blood pressure, or if you have had surgery on your chest, abdomen, head or eyes.

Risks after a spirometry test

(Video) How to do a spirometry test and interpret the results

There are few risks associated with the spirometry test itself, but there is a small risk of getting an indirect infection.

This can be done in different ways:

  • Although data are not generally available on spirometer disinfection, there may be concerns that people are at risk of infection with a variety of fungal microorganisms if the spirometer tube is not properly disinfected after each test. These include respiratory illnesses such as influenza, measles, chickenpox, pneumonia and tuberculosis. according to aResearch review 2015, researchers have found bacterial growth in the spirometer tube in at least one study.
  • Other equipment, such as breathing valves and mouthpieces, can also transmit infections. It must be disinfected and changed between patients. In addition, you must be careful with the infrastructure of the laboratory – the chair you sit in, nearby tables and surfaces, and anything else you may come into contact with. Use hand sanitizer liberally and wash your hands after testing. This can also help protect you from the coronavirus that causes COVID-19 and other viruses.
  • Because aerosolized particles are inhaled during spirometry, there is a risk of spreading airborne viral illnesses. This risk applies to both medical staff and patients who can breathe air if a previous patient is present. While a variety of illnesses can be spread through the air, the biggest concern right now is the coronavirus that causes COVID-19. Talk to your doctor before the test if you think this might be the case.Symptoms of COVID-1.
  • People with cystic fibrosis need more frequent lung function tests. However, they are also at increased risk of upper respiratory tract infection when coming into contact with testing equipment and the personnel administering the test.

This risk may be greater in other countries that have different standards and protocols to prevent the spread of infection.

A American Thoracic Society e a European Respiratory Societyhave official technical standardsto perform spirometry. This includes disinfection guidelines and the recommendation of disposable mouthpieces with filters to prevent infections.

“Normal” results for a spirometry test vary from person to person. They are based on your:

  • age
  • Height
  • Corre
  • Sex

Your doctor will calculate the predicted "normal" value for you before taking the test. After taking the test, look at the test result and compare that value to the predicted result. Your result is considered "normal" if your score is80 percentor more than 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 this as a combined number known as the FEV1/FVC ratio.

When you have a blocked airway, the amount of air you can quickly expel from your lungs is reduced. This leads to a lower FEV1 and FEV1/FVC ratio.

FVC measurement

One of the primary measurements of spirometry is FVC, which is the greatest total amount of air you can forcefully exhale after inhaling as deeply as possible. If your FVC is lower than expected, something is restricting your breathing.

"normal" or "abnormal"Resultsare evaluated differently by adults and children.

For children aged 5 to 18 years:

(Video) Understanding Spirometry - Normal, Obstructive vs Restrictive

Percentage of predicted FVC valueresult
80% or morenormal
less than 80%not normal

For adults:

is greater than or equal to the lower limit of normalnormal
is less than the lower limit of normalnot normal

An "abnormal" FVC can be caused by restrictive or obstructive lung disease, and other types of spirometry measurements are needed to determine what type of lung disease is present.

Obstructive or restrictive lung disease may be present alone, but a mixture of both forms at the same time is also possible.

FEV1 measurement

The second important measurement of spirometry is FEV1. This is the amount of air you can expel from your lungs in 1 second.

It can help your doctor assess the severity of your breathing problems. A lower-than-expected FEV1 value indicates that you may have significant respiratory failure.

Your doctor will use your FEV1 measurement to assess the severity of your breathing difficulties. The table below shows what is considered regarding your FEV1 spirometry test results according to the guidelines of theAmerican Thoracic Society:

Percentage of predicted FEV1 valueresult
80% or morenormal
70%–79%slightly abnormal
60%–69%moderately abnormal
50%–59%moderately to severely abnormal
35%–49%completely abnormal
less than 35%very strongly abnormal

FEV1/FVC ratio

Doctors usually analyze FVC and FEV1 separately and then calculate their FEV1/FVC ratio. The FEV1/FVC ratio is a number that represents the percentage of your lung capacity that you can exhale in 1 second.

In the absence of restrictive lung disease causing a normal or elevated FEV1/FVC ratio, the higher the resulting percentage of your FEV1/FVC ratio, the healthier your lungs will be.

ONElow indexindicates that something is blocking your airway. The following is considered a low score:

AgeLow FEV1/FVC ratio
5 to 18 yearsless than 85%
adultless than 70%

Spirometry creates a graph that shows your airflow over time. If your lungs are healthy, your FVC and FEV1 values ​​will be plotted in a graph that might look like thisso:

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If your lungs have been blocked in any way, your diagram might look like this:

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(Video) Spirometry: Procedure and Results

If your doctor determines that your results fall into the "abnormal" category, they'll likely run other tests to determine whether your restricted breathing is caused by a breathing disorder. This may includechest x-rays,X-rays of the sinuses, and blood tests.

Primary lung diseases that lead to unexpected spirometry results include obstructive diseases, such as asthma and COPD, and restrictive diseases, such as interstitial lung fibrosis.

Your doctor may also look for medical conditions, often associated with breathing disorders, that could make your symptoms worse. These includeAsia,allergic rhinitis, esinus infection.

Read more: How Spirometry Results Track COPD Progress.

Read this article in Spanish.

(Video) Spirometry, Lung Volumes & Capacities, Restrictive & Obstructive Diseases, Animation.


What is a normal spirometry test result? ›

Interpretations of spirometry results require comparison between an individual's measured value and the reference value. If the FVC and the FEV1 are within 80% of the reference value, the results are considered normal. The normal value for the FEV1/FVC ratio is 70% (and 65% in persons older than age 65).

What is a good number on a spirometry test? ›

Normal results typically range between 80% and 120% of the prediction. If your lung volume results fall outside of this normal range, this may suggest you have an obstructive or restrictive lung condition.

What a spirometry test score can tell you about your COPD? ›

Spirometry is a type of pulmonary function test. It measures how well your lungs are working. Your doctor uses the test results to help determine whether you have COPD or other possible lung disease. If you have COPD, the results also show how severe your COPD is.

What are normal pulmonary function test results? ›

Normal and Critical Findings

Normal findings of spirometry are an FEV1/FVC ratio of greater than 0.70 and both FEV1 and FVC above 80% of the predicted value. If lung volumes are performed, TLC above 80% of the predictive value is normal. Diffusion capacity above 75% of the predicted value is also considered normal.

How do you pass a spirometry test? ›

Keep these tips in mind:
  1. Wear loose clothing.
  2. If you smoke, avoid smoking for at least 1 hour before the test.
  3. If you drink alcohol, avoid consuming it for at least 4 hours before the test.
  4. Avoid eating or drinking for at least 2 hours before the test.

What is normal breathing lung capacity? ›

Lung capacity or total lung capacity (TLC) is the volume of air in the lungs upon the maximum effort of inspiration. Among healthy adults, the average lung capacity is about 6 liters.

How many mL is normal on a spirometer? ›

The typical value for a young adult male of normal size is about 3000 mL. C. The expiratory reserve volume, ERV, is the additional volume of air that can be expired after a normal or tidal expiration. A typical value is about 1100 mL for a young adult male.

What level should your lungs be? ›

People with healthy lungs should have an oxygen level of 80-100 mm Hg, or 95-100% when measured with a pulse oximeter.

Can you have COPD with normal spirometry? ›

The next important issue in COPD diagnosis is the uncertainty of diagnosis over time, as an individual can be diagnosed with mild COPD at first assessment but have normal spirometry results at follow-up, even without intervention.

How can you tell the difference between asthma and COPD on spirometry? ›

Commonly used spirometry measurements of relevance for the differentiation of asthma from COPD include the volume of air that can be forcibly exhaled in a single breath after a maximum inspiration (forced vital capacity [FVC]), the FEV1 of this maneuver, and the ratio of these measurements (FEV1/FVC).

How do they confirm COPD? ›

The main test for COPD is spirometry. Spirometry can detect COPD before symptoms are recognized. Your doctor also may use the test results to find out how severe your COPD is and help set your treatment goals. Spirometry is a type of lung function test that measures how much air you breathe out.

What does a failed spirometry test mean? ›

Abnormal results usually mean that you may have chest or lung disease. Some lung diseases (such as emphysema, asthma, chronic bronchitis, and infections) can make the lungs contain too much air and take longer to empty.

What does FEV1 FVC 70 mean? ›

This is a measure of how quickly the lungs can be emptied. • FEV1/FVC: FEV1 expressed as a percentage of the FVC, gives a clinically. useful index of airflow limitation. The ratio FEV1/FVC is between 70% and 80% in normal adults; a value less than 70% indicates airflow limitation and the possibility of COPD.

What is a good lung function test? ›

Spirometry is a simple test used to help diagnose and monitor certain lung conditions by measuring how much air you can breathe out in one forced breath. It's carried out using a device called a spirometer, which is a small machine attached by a cable to a mouthpiece.

How can I improve my lung spirometry? ›

Regular exercise, eating a healthy diet, and avoiding tobacco smoke can all help keep your lungs functioning at their best. If you're experiencing symptoms of low lung capacity, such as shortness of breath, it's important to see a doctor to find out if an underlying condition is causing them.

Can spirometry results be wrong? ›

Since the FEV1 is not much affected, the FEV1/FVC ratio is often falsely elevated. These false results may prevent the detection of “obstructive impairment” or be misinterpreted as indicating a “restrictive impairment.”

Can you pass a spirometry test with asthma? ›

Patients with undiagnosed asthma who consult repeatedly with symptoms ranging in severity3 may demonstrate perfectly normal spirometry.

What is considered poor lung capacity? ›

† Normal lung function: FVC% ≥ 80% and FEV1/FVC ≥ 70%. ‡ Poor lung function: FVC% < 80% and FEV1/FVC ≥ 70% or FEV1/FVC < 70%.

What is the respiratory rate for shortness of breath? ›

A respiration rate below 12 or over 25 breaths per minute while resting may signal an underlying health problem. Bradypnea can happen during sleep or when you're awake. It's not the same thing as apnea, which is when breathing completely stops. And labored breathing, or shortness of breath, is called dyspnea.

What is considered low lung capacity? ›

Our main outcome measures were low lung function (a condition determined to be present if the forced expiratory volume in 1 second–forced vital capacity ratio was less than 0.7 and the forced expiratory volume in 1 second was less than 80% of the predicted value), a physician diagnosis of OLD (chronic bronchitis, ...

What is a good lung capacity ml? ›

Total Lung Capacity(TLC)

The normal value is about 6,000mL(4‐6 L). TLC is calculated by summation of the four primary lung volumes (TV, IRV, ERV, RV).

What is a dangerously low oxygen level? ›

People should contact a health care provider if their oxygen saturation readings drop below 92%, as it may be a sign of hypoxia, a condition in which not enough oxygen reaches the body's tissues. If blood oxygen saturation levels fall to 88% or lower, seek immediate medical attention, says Dr.

What is the best exercise to increase lung capacity? ›

Both aerobic activities and muscle-strengthening activities can benefit your lungs. Aerobic activities like walking, running or jumping rope give your heart and lungs the kind of workout they need to function efficiently.

What should blood oxygen be while sleeping? ›

Everyone's oxygen levels in the blood are lower during sleep, due to a mildly reduced level of breathing. Also, some alveoli drop out of use during sleep. If your waking oxygen saturation is greater than about 94 percent on room air, it is unlikely that your saturation during sleep will fall below 88 percent.

What conditions can be diagnosed with spirometry? ›

Spirometry is used to diagnose asthma, chronic obstructive pulmonary disease (COPD) and other conditions that affect breathing. Spirometry may also be used periodically to monitor your lung condition and check whether a treatment for a chronic lung condition is helping you breathe better.

What is the most common cause of shortness of breath? ›

Most cases of shortness of breath are due to heart or lung conditions. Your heart and lungs are involved in transporting oxygen to your tissues and removing carbon dioxide, and problems with either of these processes affect your breathing.

Does emphysema show up on spirometry? ›

Our results demonstrate that a few anamnestic questions plus spirometric data can provide significant evidence on the presence of lung emphysema which subsequently can be substantiated by ordering a CT scan.

How accurate is spirometry for COPD? ›

COPD-6, PIKO-6, and PEF are three commonly used portable spirometers in clinical practice. From a diagnostic accuracy perspective, PIKO-6 has the highest diagnostic accuracy rate (95%), followed by COPD-6 (91%) and PEF (82%) with statistically significant difference among them (P < 0.05).

Does COPD show up in a chest xray? ›

While a chest x-ray may not show COPD until it is severe, the images may show enlarged lungs, air pockets (bullae) or a flattened diaphragm. A chest x-ray may also be used to determine if another condition may be causing symptoms similar to COPD.

Can you have good oxygen levels with asthma? ›

Asthmatics are notoriously good oxygen compensators and can have near-normal or completely normal oxygen stats during the midst of a severe asthma attack. Asthma is a disease of the airways, not the little air sacs (alveoli) where the gas exchange itself takes place.

What are 2 symptoms of COPD? ›

Symptoms of COPD include:
  • Frequent coughing or wheezing.
  • Excess phlegm or sputum.
  • Shortness of breath.
  • Trouble taking a deep breath.

What is the earliest symptom of COPD? ›

Symptoms include breathing difficulty, cough, mucus (sputum) production and wheezing. It's typically caused by long-term exposure to irritating gases or particulate matter, most often from cigarette smoke. People with COPD are at increased risk of developing heart disease, lung cancer and a variety of other conditions.

What does early COPD look like? ›

It often starts with a nagging cough. It could be dry, or you might have mucus that's clear, white, yellow, or green. You may also find that you're short of breath sometimes, especially if you push yourself.

How do you not pass a spirometry test? ›

Spirometry is a test of maximal effort, therefore, a slight hesitation or a delayed start can affect results, and so is one of the common mistakes when performing Spirometry. A hesitation in blowing out before the initial blast affects most spirometry test results early in the manoeuvre.

Can spirometry detect heart problems? ›

While it's often assumed that spirometry is a lung-health specific diagnostic tool, it also plays a vital role in assessing cardiovascular risk, including coronary artery disease.

How do you know your lungs is failing? ›

Symptoms include shortness of breath or feeling like you can't get enough air, extreme tiredness, an inability to exercise as you did before, and sleepiness.

What might a low FEV1 FVC (< 70 %) suggest? ›

A low FEV1/FVC ratio (the forced expiratory volume in 1 second divided by the forced vital capacity) indicates an obstructive pattern, whereas a normal value indicates either a restrictive or a normal pattern.

What FEV1 FVC indicates asthma? ›

The Global Initiative for Asthma (GINA) defines asthma by combining variable respiratory symptoms with variable expiratory airflow limitation, expressed as an FEV1/FVC ratio less than 75-80% (7).

What is considered to be the minimum acceptable FEV1 FVC ratio for older adults? ›

Conclusion: Adjustments of the GOLD criteria for diagnosing COPD are needed, and FEV(1)/FVC ratios down to 65% should be regarded as normal when aged 70 years and older.

What is a good number on a spirometer? ›

Normal values in healthy males aged 20-60 range from 4.5 to 3.5 liters, and normal values for females aged 20-60 range from 3.25 to 2.5 liters.

What percentage of lung function is needed to live? ›

o You need to understand that if lung function has fallen to less than 30% of normal then 50 in 100 patients will die within 2-3 years and 50 in 100 will be alive.

Is an FVC of 1.78 normal? ›

Forced Vital Capacity (FVC)

The volume is measured in liters. Average normal values for healthy males age 20-60 range from 4.75 to 5.5 liters. For females age 20-60, the normal range is from 3.25 to 3.75 liters.

What would a FEV1 of 40 60 indicate? ›

The ratio FEV1/FVC is between 70% and 80% in normal adults; a value less than 70% indicates airflow limitation and the possibility of COPD. FEV1 is influenced by the age, sex, height, and ethnicity, and is best considered as a percentage of the predicted normal value.

What spirometry results indicate asthma? ›

If your FEV1 increases after taking a bronchodilator (usually albuterol), then your airway blockage is reversible. This is a sign of asthma. The percentages can also tell you how severe or well-controlled your asthma is. An FEV1 of less than 60 percent often means your asthma is severe or poorly controlled.

What is a good reading on an incentive spirometer? ›

Most people start with a goal of 500 mL or cc. Your healthcare provider may change your goal and have you aim for higher numbers as you heal from surgery. The package your incentive spirometer came in should also have a chart. You can use the chart to set your goal based on your age, height, and sex.

What FVC value indicates a lung problem? ›

The ratio of FVC and FEV1 can help doctors diagnose the specific type of lung disease a person has. To calculate this ratio, a doctor divides the FVC reading by the FEV1 result. When the value of FEV1 is less than 70% of an FVC in adults or below 85% in those aged 5–18 years, an obstruction may be present.

What is an abnormal FVC? ›

A diminished FVC value is a sign of several conditions, including: Chronic obstructive pulmonary disease (COPD), including chronic bronchitis, emphysema, and bronchiectasis. Restrictive airway diseases, such as idiopathic pulmonary fibrosis.

What is the normal rate of FEV1 decline with age? ›

Forced expiratory volume (FEV1): the amount of air you can exhale with force in 1 second. FEV1 declines 1 to 2 percent per year after about the age of 25, which may not sound like much but adds up over the course of a lifetime.

What is the of FEV1 for severe lung disease? ›

GOLD 1 - mild: FEV1 ≥80% predicted. GOLD 2 - moderate: 50% ≤ FEV1 <80% predicted. GOLD 3 - severe: 30% ≤ FEV1 <50% predicted. GOLD 4 - very severe: FEV1 <30% predicted.

What is the level of FEV1 in a person who has COPD? ›

The main criterion for COPD is a FEV1/FVC ratio <70%. Subclassification into mild, moderate, severe and very severe disease is achieved by including various levels of FEV1 as percentage of predicted value 2.

Does normal spirometry mean no asthma? ›

The diagnosis is clear cut if spirometry in a patient with a history suggestive of asthma demonstrates airflow obstruction with reversibility. However, if the test is normal, asthma cannot be excluded.

How do you know if you have asthma or COPD? ›

One main difference is that asthma typically causes attacks of wheezing and tightness in your chest. COPD symptoms are usually more constant and can include a cough that brings up phlegm.


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