Spirometry
Spirometry is the basic, non-invasive lung function test that measures the volume and speed of airflow during breathing — the foundation for diagnosing asthma, COPD, and other respiratory conditions and for tracking their course over time.
Number of studies
2
Safety
Requires caution
Time to effects
Not applicable — spirometry is a diagnostic test, not an intervention.
Who it's for
Table of contents
TL;DR
Spirometry is the basic, non-invasive lung function test that measures the volume and speed of airflow during breathing — the foundation for diagnosing asthma, COPD, and other respiratory conditions and for tracking their course over time.
- →The only widely available test that objectively confirms or rules out airway obstruction
- →Differentiates an obstructive pattern (asthma, COPD) from a restrictive one (interstitial lung disease, chest wall deformities)
- →Enables objective monitoring of lung disease progression and treatment response over time
| Test type | Functional measurement of air volume and flow during forced breathing |
|---|---|
| Level of evidence | Strong — ATS/ERS standard in diagnosing obstructive and restrictive lung disease |
| Target group | People with chronic cough, breathlessness, wheezing, or suspected asthma/COPD |
| Key parameters | FVC, FEV1, FEV1/FVC ratio, flow-volume curve |
| Duration | About 15–25 minutes, requires several repeats of the breathing maneuver |
| Status | First-line test, widely available in primary care and pulmonology clinics |
Understand
Overview
Spirometry is a basic lung function test that measures the volume of air inhaled and exhaled by the lungs and the speed at which air is blown out during a forced exhalation. The patient breathes through a mouthpiece connected to a spirometer — a device that records airflow and volume in real time — performing a series of breathing maneuvers, the most important of which is the forced exhalation: a deep breath in, followed by the fastest and most complete exhalation possible. The result is a flow-volume curve along with a set of numerical parameters, the two most clinically important being FEV1 (forced expiratory volume in one second) and FVC (forced vital capacity).
The clinical value of spirometry lies in the fact that it is the only widely available test that objectively confirms or rules out airway obstruction — narrowing of the bronchi that impedes airflow, characteristic of asthma and chronic obstructive pulmonary disease (COPD). An FEV1/FVC ratio below the lower limit of normal is the key criterion for diagnosing obstruction, while a restrictive pattern (reduced FVC with a normal FEV1/FVC ratio) instead suggests interstitial lung disease, chest wall deformities, or neuromuscular disorders limiting lung expansion. Unlike simply assessing symptoms or listening to the chest, spirometry provides a numerical, reproducible result that can be compared over time and between tests.
The test is ordered in many different clinical contexts. Most often it's performed in people reporting chronic cough, exertional breathlessness, wheezing, or a feeling of chest tightness, to confirm or rule out asthma or COPD. It's also a routine part of monitoring already-diagnosed lung diseases, assessing response to bronchodilator treatment, pre-surgical evaluation of smokers and people with lung disease, occupational screening in jobs exposed to dust and airway irritants, and monitoring pulmonary toxicity from certain cancer drugs.
On the practical side, the test is quick — performing the maneuvers takes roughly fifteen to twenty-odd minutes, though it requires active patient cooperation and usually several repetitions to obtain three technically acceptable, reproducible curves. Before the test, patients are usually advised to avoid short-acting bronchodilators for a few hours (if the goal is to assess baseline lung function without their effect), avoid intense physical exertion right before the test, and avoid a heavy meal. The result is available immediately after the test as a printout with the flow-volume curve and a table of values compared to predicted norms for the patient's age, sex, height, and ethnicity.
A common misconception is treating spirometry as simple "blowing into a tube" that doesn't require particular technical precision — in reality, the quality of the result depends heavily on how well the maneuver is performed, and errors such as an incomplete initial breath, premature termination of the exhalation, or coughing during the maneuver can significantly lower or distort the result. That's why the guidelines standardizing the test precisely define acceptability and repeatability criteria for the curves, and the experience of the person administering the test directly affects how reliable the result is.
Spirometry is often extended with a bronchodilator reversibility test — repeating the test roughly fifteen minutes after administering a bronchodilator — which assesses the reversibility of obstruction and is one of the criteria differentiating asthma (obstruction usually reversible) from COPD (obstruction usually only partially reversible or irreversible). Variants of the test also include bronchial challenge testing (e.g., with methacholine) in diagnosing asthma with an ambiguous presentation, and cardiopulmonary exercise testing (CPET), which combines spirometry with exercise and gas exchange measurement.
Spirometry remains the first-line test in diagnosing obstructive and restrictive lung disease precisely because it's inexpensive, widely available, non-invasive, and provides an objective, quantitative picture of respiratory function that symptom assessment alone can't fully replace. Its value grows with regular repetition — a single result gives a snapshot of lung status at a given moment, but a series of measurements over time captures the pace of disease progression or the effectiveness of treatment, which has direct bearing on treatment decisions.
Mechanism of action
A spirometer measures airflow (via pneumotachographic, turbine, or ultrasonic sensor methods, depending on the device model) during breathing maneuvers performed by the patient, then integrates the flow signal over time to calculate volume. The key maneuver is the forced exhalation: after a maximal inhalation, the patient performs the fastest and most complete exhalation possible, usually lasting at least 6 seconds in adults, until a volume plateau is reached. From this single curve, the device calculates dozens of parameters, the clinically important ones being primarily FVC (the total volume exhaled during the maneuver), FEV1 (the volume exhaled in the first second), and their ratio, FEV1/FVC.
The physiological meaning of these parameters stems from the mechanics of breathing. FVC reflects the total lung capacity available for air exchange at maximal inhalation and exhalation — its reduction suggests limited expandability of the lungs or chest wall (a restrictive pattern). FEV1, on the other hand, depends on airway resistance to flow — the narrower the bronchi due to smooth muscle contraction, mucosal swelling, or excess secretions, the more slowly air can be blown out in the first second, even though total FVC may remain normal. An FEV1/FVC ratio below the lower limit of normal (rather than a fixed value of 0.7, as older criteria assumed) is the mathematical expression of this disproportion and defines an obstructive pattern.
Interpreting the result requires comparing the measured values to predicted values, calculated from reference equations that account for the subject's age, sex, height, and ethnicity — the same FEV1 and FVC numbers mean something entirely different in a twenty-year-old man versus a seventy-year-old woman. Modern reference equations express the result as a percentile or z-score relative to a healthy population, which is more accurate than the older approach based on a fixed percentage of the predicted value, especially at the extremes of the age range.
The bronchodilator reversibility test uses the reversibility of bronchospasm as a diagnostic tool — if, after administering a short-acting bronchodilator (e.g., salbutamol), FEV1 increases by at least 12% and 200 mL relative to the baseline value, this is considered a significant bronchodilator response, suggesting a reversible bronchospasm component typical of asthma, although its absence doesn't rule out the diagnosis. This mechanism directly exploits the pharmacological relaxation of bronchial smooth muscle by beta-2-adrenergic receptor agonists, which reduces airway resistance and translates into a measurable improvement in flow parameters.
Recording airflow
The spirometer measures airflow in real time during the patient's forced exhalation using pneumotachographic, turbine, or ultrasonic methods.
Integrating the signal into volume
The software integrates the measured flow over time, calculating FVC and FEV1 volumes and generating the flow-volume curve.
Comparison to predicted values
The measured parameters are compared against reference equations accounting for age, sex, height, and ethnicity to determine whether the result falls within normal range.
Assessing pattern and reversibility
The FEV1/FVC ratio differentiates an obstructive from a restrictive pattern, and an optional bronchodilator test after a bronchodilator assesses the reversibility of obstruction.
Evidence: strong — based on 2 studies in this database.
Benefits
Common myths
MythSpirometry is a simple test where the technique used doesn't much matter.
FactThe quality of the result depends heavily on correct maneuver technique — an incomplete breath, premature termination of the exhalation, or coughing can significantly lower or distort the result, which is why guidelines precisely define acceptability criteria for the curves.
MythA normal spirometry result rules out asthma.
FactAsthma can be intermittent, and lung function may be normal between flare-ups. A normal resting result doesn't rule out asthma if symptoms are typical — a bronchial challenge test may then be indicated.
MythYou need to fast before spirometry, just like for blood tests.
FactThere's no need to fast, though a heavy meal right before the test is best avoided, since significant stomach distension makes a full inhalation and exhalation harder.
MythThe spirometry result is the same regardless of the patient's age and sex.
FactFEV1 and FVC values are always interpreted relative to predicted values, calculated from equations accounting for age, sex, height, and ethnicity — the same absolute numbers can be normal in one person and abnormal in another.
Forms & variants
Spirometry comes in several forms that differ in bioavailability and use case — the form you pick genuinely matters for how effective the supplementation is.
Spirometry with bronchodilator reversibility testing
Repeating the test roughly fifteen minutes after administering a bronchodilator.
Best for: Differentiating asthma from COPD, assessing reversibility of obstruction
Spirometry with bronchial challenge testing (e.g., methacholine)
Assessing bronchial hyperreactivity after administering a bronchoconstrictive substance, performed at specialist centers.
Best for: Diagnosing asthma with a normal resting spirometry result and ambiguous symptoms
Cardiopulmonary exercise testing (CPET)
Spirometry combined with physical exertion on a treadmill or ergometer and gas exchange measurement.
Best for: Assessing cardiorespiratory fitness and differentiating causes of exertional breathlessness
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Practice
Frequently asked questions
It's recommended to avoid short-acting bronchodilators for a few hours before the test (unless your doctor advises otherwise), avoid intense physical exertion and a heavy meal right before the test, and avoid smoking in the hours beforehand.
No — the test is completely non-invasive and painless, though it requires intense respiratory effort during the forced exhalation maneuver, which can feel tiring, especially with several repetitions.
Usually three to eight attempts are performed until at least three technically acceptable and mutually reproducible curves are obtained, allowing the result to be considered reliable.
A bronchodilator reversibility test is an extension of standard spirometry — after the first measurement, a bronchodilator is administered, and after about fifteen minutes the test is repeated to assess whether and how much flow parameters improve.
Yes, usually from around age 5–6, provided the child can understand and perform the breathing maneuver instructions — in younger children, the reliability of the test is often limited by cooperation difficulties.
What to combine with
Good combinations
VO2 max — Spiroergometria łączy spirometrię z pomiarem VO2max, dając pełniejszy obraz wydolności oddechowo-krążeniowej niż każde z badań osobno
CRP and hs-CRP — W przewlekłych chorobach zapalnych płuc warto zestawiać wynik czynnościowy spirometrii z markerem ogólnoustrojowego stanu zapalnego
Safety
Side effects & contraindications
Possible side effects
Transient dizziness or lightheadedness from hyperventilation during the forced exhalation maneuver
Rarely: a coughing fit or an incidental vasovagal fainting episode in predisposed individuals during forceful exhalation
Contraindications
Recent heart attack, unstable angina, or thoracic/abdominal aortic aneurysm within the past few weeks — due to the sharp rise in intrathoracic pressure during the maneuver
Pneumothorax within the past few weeks, or recent surgery of the chest, abdomen, or eye
Active hemoptysis of unexplained cause
Interactions
Short-acting bronchodilators taken right before the test can mask baseline obstruction if the goal is to assess status without their effect
An active respiratory infection in the preceding weeks can transiently lower results independent of chronic lung disease
Intense physical exertion right before the test can affect flow parameters and should be avoided
A heavy meal or significant stomach distension makes a full inhalation and exhalation harder, lowering the technical quality of the maneuver
Smoking in the hours before the test can transiently alter flow parameters
Insufficient understanding of instructions or poor patient cooperation (e.g., in young children) lowers the repeatability and reliability of the result
Is it worth taking?
Who it's for
- People with chronic cough, exertional breathlessness, or wheezing of unclear cause
- Patients with already-diagnosed asthma or COPD requiring monitoring of disease course
- Smokers and former smokers as part of COPD risk assessment
- People occupationally exposed to industrial dust, chemical fumes, or other airway irritants
Not for
- Recent heart attack, unstable angina, or thoracic/abdominal aortic aneurysm within the past few weeks — due to the sharp rise in intrathoracic pressure during the maneuver
- Pneumothorax within the past few weeks, or recent surgery of the chest, abdomen, or eye
- Active hemoptysis of unexplained cause
Evidence
Worth knowing
An FEV1/FVC ratio below the lower limit of normal is the key criterion for diagnosing airway obstruction.
An FEV1 increase of at least 12% and 200 mL after a bronchodilator is considered a significant bronchodilator response.
A correct forced exhalation maneuver usually lasts at least 6 seconds in adults, until a plateau in exhaled volume is reached.
Modern reference equations (Global Lung Function Initiative) express the result as a percentile relative to a healthy population, rather than a fixed percentage of the predicted value.
Studies
Spirometry remains an essential tool for diagnosing and monitoring respiratory disease, and the quality of the breathing maneuver directly determines how reliable the resulting measurement is.
Graham BL et al., Standardization of Spirometry 2019 Update, American Journal of Respiratory and Critical Care Medicine, 2019
Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement
Strong evidenceGraham BL, Steenbruggen I, Miller MR, Barjaktarevic IZ, Cooper BG, Hall GL, Hallstrand TS, et al. · American Journal of Respiratory and Critical Care Medicine · 2019
The official ATS/ERS technical statement standardizing the performance and interpretation of spirometry, defining acceptability and repeatability criteria for breathing maneuvers.
View studyMulti-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations
Strong evidenceQuanjer PH, Stanojevic S, Cole TJ, Baur X, Hall GL, Culver BH, Enright PL, et al. · European Respiratory Journal · 2012
A Global Lung Function Initiative report presenting multi-ethnic reference equations for spirometry across the 3–95 year age range, now the current standard for result interpretation.
View studySources & bibliography
- Graham et al. 2019 — Am J Respir Crit Care Med, Standardization of Spirometry
- Quanjer et al. 2012 — Eur Respir J, Global Lung Function 2012 Equations
The PubMed identifiers in this knowledge base were checked against NCBI records (October 2026). If you spot an error in a source, please let us know via the contact form.
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VitMode Editorial — Hormones and Endocrinology is the VitMode editorial team responsible for: hormones, testosterone therapy, the thyroid and metabolism. The team has no individual bylines — texts are prepared by VitMode editors from primary sources (clinical trials, meta-analyses, guidelines). Every cited PubMed paper is automatically checked for a matching identifier, title and publication year. The content is educational and does not replace medical advice. Factual errors can be reported in a comment under the post or through the contact form; corrections are made by the editorial team.
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Editorial review
Redakcja VitMode — Badania i biomarkeryEditorial team
VitMode Editorial — Lab Tests and Biomarkers is the VitMode editorial team responsible for: laboratory tests, interpreting results and ageing biomarkers. The team has no individual bylines — texts are prepared by VitMode editors from primary sources (clinical trials, meta-analyses, guidelines). Every cited PubMed paper is automatically checked for a matching identifier, title and publication year. The content is educational and does not replace medical advice. Factual errors can be reported in a comment under the post or through the contact form; corrections are made by the editorial team.
272 publications on this site
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