Spirometry (examination): how it is done and analysis of results


What is spirometry?

Spirometry, or breath testing , measures air volume and velocity in order to diagnose lung and respiratory diseases. The procedure is simple, painless and lasts about half an hour.

Other well-known names for this test are Ventilatory Test or Pulmonary Function Test.

Occupational spirometry

A variation of the test is occupational spirometry, performed at the workplace. This type of spirometry assesses the health of workers who have direct contact with pollutants and who, therefore, can acquire diseases in the workplace.

What is it for?

The test serves to assess lung function, which helps in the diagnosis of respiratory problems in the patient. In addition, it is usually used to monitor the evolution of degenerative diseases and as a preoperative procedure, to check the patient’s lung health.

In some cases, it can also be done in healthy people who need to measure their breathing capacity for some reason, as is the case with athletes.

Some diseases that are accompanied by spirometry are:

  • DPOC;
  • Bronchitis;
  • Asthma;
  • Pulmonary emphysema;
  • Pulmonary fibrosis.

How is spirometry done?

Before starting spirometry, the patient has his height and weight measured, and must rest for about 5 to 10 minutes. Meanwhile, the doctor takes the opportunity to ask about possible symptoms.

During the examination, the patient sits and a rubber band is placed on his nose, so that he can breathe only through his mouth. The doctor gives you a tube, which is connected to a device called a spirometer. All the patient must do is blow through the spirometer, throwing the air into the tube, with the greatest possible force.

The patient will breathe calmly until the doctor asks to change the breathing. Then, it is necessary to breathe faster and harder. It is recommended that the patient avoid coughing or talking during the test, as such actions alter the result.

Oscillations are recorded in the form of graphs and tables by a computer. These charts must be analyzed by the pulmonologist , who will interpret the curves and understand the patient’s lung health.

The test is usually repeated about three times to ensure the accuracy of the results. However, before the repetition, the patient receives a bronchodilator medication, and must wait about 20 minutes to start the second test.

Bronchodilator drugs are substances that dilate the bronchi, facilitating breathing in individuals with asthma attacks and bronchitis , for example. They are used in the exam in order to compare the individual’s normal breathing with breathing under the effect of the medication.


Clear all your doubts before taking the test, as the correct performance of all steps of the exam is important.

What about occupational spirometry?

It is a similar procedure, but it occurs in a simplified way and in the work environment.

This test does not require the use of a bronchodilator and is much more basic, as only the first phase of murmurs occurs. Based on it, the condition of the worker is evaluated, and this can be transferred to another sector / function that is less harmful to your health, if necessary.

Complementary exams

Some similar tests may be requested after spirometry, as they also assess the patient’s breathing in other conditions, such as during physical stress .

Among them, there is the treadmill test and the ergonomic bicycle test, which measure breathing in each movement performed.

How to prepare

Before the exam, care must be taken to avoid complications. All of the following recommendations must be strictly followed so that the spirometry values ​​do not change:

  • Go well-fed, but avoid eating a heavy meal;
  • Wear comfortable, loose clothing that does not impair your breathing;
  • Do not consume soda, coffee, tea, chocolate or any food that contains caffeine at least 6 hours before the exam;
  • Do not drink alcohol for at least 24 hours before spirometry;
  • Stop the practice of physical exercises on this day;
  • Discontinue the use of cigarettes 2 hours before the exam, if you are a smoker;
  • Reschedule the exam in case of flu or cold, as this affects the results;
  • Stop using any medication the doctor deems necessary.

Bronchodilators before the exam

It is recommended not to use bronchodilators right before the test. However, if necessary, the medication can be used around 4 hours before the procedure, if it is of a short duration. The long-term one must be used, at the most, 12 hours before the exam.

When to do spirometry?

The test is indicated for prevention and for people who have or may have respiratory and lung problems. In case of suspicion of any disease of the type, the person should take the exam as a precaution.

Smokers should also have the test done to assess their lung function and possible illnesses.

Patients who have asthma , bronchitis, pulmonary fibrosis and the like must also undergo the examination, so that they can monitor and analyze lung problems, checking if the respiratory problems are under control. It is recommended that, in these cases, the patient undergo periodic examinations every 3 months or every 6 months.

World Spirometry Day

The 14th of October is the celebration of the world day of spirometry, which aims to make people aware of the exam, identifying diseases at an early stage so that they can be treated early. On this date, some institutions take the exam for free.

Exam Price

The spirometry exam costs approximately R $ 100.00. This value may vary depending on the clinic and specific assessments.

Where to do it

You can schedule a spirometry test at a health clinic near your home or in a hospital. If you have routine exams, the general practitioner or pulmonologist can advise you on this exam by referring you.

Interpretation of results

The reference values ​​change according to the age, sex and size of the patient, and are usually informed after the exam.

The doctor explains the results to the patient and, if the test result changes, a new exam is requested. If the change persists, more suitable treatments for each disease are initiated.

There are two types of results that indicate the presence of respiratory problems:

FEV1 or FEV1 (forced expiratory volume)

It is the assessment of the amount of air exhaled in 1 second, quickly. If it is below normal, it means that the patient may have asthma or COPD .

FVC or FVC (forced vital capacity)

It is the assessment of the amount of air exhaled in the shortest possible time. When it is lower than normal, it indicates the presence of diseases that prevent or hinder the expansion of the lung (example: cystic fibrosis ).


This is the ratio between the forced expiratory volume and the forced vital capacity that tends to decrease with age. Below-normal values ​​may indicate asthma, COPD, chronic bronchitis or emphysema.


Spirometry is usually a quiet and safe test. What can happen is that the patient feels dizzy or short of breath after the process, which is common.

The test rarely causes breathing problems in patients, and it is not done in people with unstable heart conditions, as some effort is required during the examination.

After the exam, there is no need for rest. The patient can resume normal activities.

Spirometry is a simple, quick and painless procedure that can help you prevent health problems early. So, share this idea with friends and family and, if you have any questions, contact us.