Spirometry for bronchial asthma and interpretation of the results

Bronchial asthma is a common disease. About 5-10% of the world’s population suffers from this pathology. Diagnosis of the disease is a complex multi-stage process.

Spirometry prescribed to patients with bronchial asthma is an important diagnostic study. It allows you to study the ventilation function of the lungs in asthmatics.

Spirometry is prescribed to finalize the diagnosis and determine the severity of bronchial asthma.

What is spirometry

Spirometry is a study that allows you to study the respiratory volume of the lungs using a special device. With its help, the volume of exhaled air is measured. Moreover, the analysis is carried out both at rest, when breathing should be normal, and under load.

Spirometry is considered a safe and painless procedure. Moreover, it is a highly effective method for assessing respiratory function.

After the end of the examination, the doctor receives a number of data, having studied which, it is possible to determine not only the type of pathology, but also the degree of lung damage.

Spirometry in the diagnosis of bronchial asthma

When diagnosing, spirometry is often prescribed to the patient, it is effective for detecting pathologies of the respiratory tract and bronchial asthma. The procedure itself is completely painless and does not cause any serious inconvenience to the patient.

Initially, a patient suspected of having asthma is examined according to the standard scheme shown to all patients with respiratory disorders. Then an additional test is made with bronchodilators.

In conclusion, in addition to the general results of spirography, indicate the type of bronchial asthma and the most suitable bronchodilator drug.

The study of spirometry indicators obtained during the examination of a patient with suspected bronchial asthma makes it possible not only to determine the cause of bronchial obstruction, but also the degree of their damage.

Spirometry is prescribed:

  1. At the initial diagnosis.
  2. When choosing an effective treatment.
  3. To control the course of the disease. In case of mild to moderate illness, it is enough to be examined once a year, in case of severe disease, at least once every 6 months.

What can be assessed using spirometry

Not all patients with a diagnosis of bronchial asthma understand the need for spirography. Meanwhile, this is a very important diagnostic study.

During it, using a special device, you can estimate the volume of exhaled air. The new generation devices also determine its composition during inhalation and exhalation. This allows you to assess the efficiency of gas exchange in the lungs.

The recording is carried out in several modes: free breathing, under stress, after taking medication, and so on. At the same time, a number of important indicators are recorded.

In the background, the following are evaluated:

  1. Respiratory volume (TO). This indicator shows the volume of inhaled and exhaled air. The study is carried out in a calm state. The patient is advised to sit.
  2. Respiratory rate in one minute (RR).
  3. Respiratory minute volume (MRV).
  4. Lung vital capacity (VC).

After that, to assess the function of external respiration of a patient suffering from bronchial asthma, a number of studies are carried out.

The main indicators that are measured during forced inhalation and exhalation include:

  1. FEV1. This is the volume of exhaled exhaled with effort in the first second.
  2. FZHEL. Fixed vital capacity of the lungs.
  3. Tiffeneau’s index. In the case of bronchial asthma, this indicator must be calculated. It is calculated by the ratio of VC to FVC.
  4. The maximum expiration rate made with effort.

All these indicators are usually estimated as a percentage, and the state of functioning of normal, healthy lungs is taken as 100%.

At the third stage, bronchodilators, mostly short-acting, are administered to the patient, and testing is repeated.

In some cases, provocative tests are possible. For example, histamine is used for this. In this case, the reaction of the bronchi is assessed.

This test is used in case of difficult diagnosis of the disease. This is the most dangerous stage of the study, and it is prescribed in exceptional cases. During carrying out, constant monitoring of the patient’s condition is required.

Indications and contraindications for research

Spirography, prescribed for bronchial asthma, like almost any diagnostic method, has its own indications and contraindications. Research is recommended and carried out if:

  • the patient often experiences pressing pains localized in the chest area;
  • the patient has a long experience of a smoker;
  • for 3-4 weeks the patient suffers from a persistent cough;
  • there is a suspicion of pulmonary obstruction;
  • there are problems with airway patency;
  • bronchial asthma attacks became more frequent than usual;
  • if there is a risk of a hereditary predisposition to pathology;
  • the patient complains of shortness of breath;
  • working conditions are associated with contact with allergens.

Despite the fact that the procedure is considered safe, not all patients can be prescribed it. Spirography is not recommended in the presence of the following conditions and pathologies:

  • any chronic disease in the acute stage;
  • high blood pressure;
  • angina pectoris;
  • hypertensive crisis;
  • heart attack;
  • circulatory problems;
  • pulmonary insufficiency;
  • toxicosis during pregnancy.

Spirography is recommended when the patient is at least 6 years old. It is at this age that it is already possible to ensure the control of inhalation and exhalation.

Before carrying out the procedure, it is obligatory to consult your doctor. For example, if a doctor thinks that a test might trigger an asthma attack, he or she may recommend another diagnostic test.

Preparation rules

For the examination, the patient must not eat for several hours. The optimal time for diagnosis is morning.

The day before the study, it is recommended to exclude the intake of any medications with bronchodilatory properties.

The patient is required to stop smoking 6 hours before the procedure. Tea and coffee are not recommended on the day of the study.

The procedure itself takes at least 10 minutes. Moreover, before starting testing, the patient should be given time to calm down and bring his breathing back to normal.

If the patient uses an inhaler, it is important to remember to take it with them.

Dizziness is possible during spirography. This condition is not dangerous in itself. An exercise test can trigger an asthma attack.

How the research is done

Correct actions of the staff and the patient during the spirogram in bronchial asthma allow you to get the most accurate result.

If all the requirements of the doctor are met, the procedure does not cause unpleasant emotions and sensations in the patient. It is important to ensure that the patient does not feel anxiety and excitement during the operation of the spirometer.

The main purpose of the study is to assess the working volume of the lungs. In this case, it is necessary to exclude or confirm the presence of certain pathological processes.

To obtain the most accurate result, the procedure is carried out in a semi-dark room. It is advisable to exclude loud sounds and other annoying factors. The recommended air temperature is from 18 to 24C.

In the study, different models of apparatus for measuring respiration parameters are used, ranging from a purely mechanical device to a modern computer spirometer.

The research is carried out according to the following method:

  1. A patient suffering from bronchial asthma needs to be seated. Examination while standing can greatly distort the main indicators of spirography, which will be significantly higher than normal.
  2. A special clip is put on the patient’s nose.
  3. The patient is given a special sterile mouthpiece. Several calm breaths are performed through it.
  4. After this, a series of inhalations and exhalations are performed with maximum amplitude.
  5. Pause 20 seconds.
  6. Inhale and exhale again at the usual pace.
  7. The last breath is performed at the highest possible rate.

If necessary, the doctor may ask the patient to take as deep breaths and exhalations as possible for 20 seconds.

The whole procedure takes no more than 15 minutes. After that, the patient needs rest for some time.

Additionally, a test with bronchodilators may be prescribed. In this case, there are a number of differences from the standard procedure.

In the beginning, everything is done as in a normal study. The patient is then given a bronchodilator, most often by inhalation. After a short period of time, the procedure is repeated.

This study allows you to choose the right drug with the greatest therapeutic effect. You can also detect spasms in the bronchi and understand whether the obstruction processes are reversible.

Decoding the results

When conducting spirometry, the following indicators are evaluated, which are important in the diagnosis of bronchial asthma:

  1. Respiration rate is an important indicator. At rest, a normal adult should have no more than 16-18 respiratory cycles per minute. In a child, this indicator is much higher. In bronchial asthma, the RR also increases.
  2. Respiratory volume. This value shows how much air (volume) a person’s lungs can hold in one breath. For men, this value is higher.
  3. Respiratory minute volume. This is the total volume of air passing through the patient’s lungs in one minute. Values ​​from 4 to 10 liters are considered standard.
  4. Forced vital capacity of the lungs. To measure this indicator, the patient first needs to inhale as deeply as possible, and then exhale as deeply as possible.
  5. Forced expiratory volume per second. The indicator depends on the age and gender of the subject. In this case, it is estimated how much air the patient can exhale in the first second.
  6. Tiffeneau’s index. Allows you to assess the patency of the lungs.

If a patient has bronchial asthma, then spirometry will reveal deviations in certain indicators.

When decoding a spirogram in bronchial asthma, the following parameters are taken into account:

  • patient gender;
  • age;
  • growth;
  • weight.

They should be taken into account, since some indicators have a wide range of acceptable boundaries. What is normal for one person may turn out to be pathology for another.


Spirometry is the fundamental diagnostic method used [M33] in bronchial asthma.

A rather harmless and painless procedure for the patient allows not only to identify the pathology itself, but also to determine the severity of the course of the disease.

However, the study also has contraindications. Before carrying out it, you need to get an appointment from your doctor.

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