FVD indicators in bronchial asthma. Spirometry in bronchial asthma FVD in bronchial asthma indicators

The FVD study is a simple and informative way to evaluate performance respiratory system. If a person has a suspicion of a violation, then the doctor suggests that he undergo a functional diagnosis.

What is FVD? In what cases is it done to an adult and a child?

FVD is a set of studies that determine the ventilation capacity of the lungs. This concept includes the full, residual volume of air in the lungs, the speed of air movement in different departments. The obtained values ​​are compared with the average, on the basis of this, conclusions are drawn about the patient's health status.

The examination is carried out in order to obtain average statistical data on the health of the population in the region, to monitor the effectiveness of therapy, dynamic monitoring of the patient's condition and the progression of pathology.

FVD of the lungs, what it is, the patient can find out when a number of complaints appear:

• asthma attacks;
• chronic cough;
• frequent incidence of respiratory diseases;
• if shortness of breath appears, but cardiovascular pathologies are excluded;
• cyanosis of the nasolabial triangle;
• with the appearance of fetid sputum with pus or other inclusions;
• if there are laboratory signs of excess carbon dioxide in the blood;
• the appearance of pain in the chest.

The procedure is prescribed without complaints, in chronic smokers and athletes. The first category acquires a tendency to diseases of the respiratory system. The second resorts to spirometry to assess how much reserve the system has. This determines the maximum possible load.

Before surgery, the respiratory function, evaluation of the results, helps to get an idea of ​​the localization of the pathological process, the degree of respiratory failure.

If the patient is being examined for disability, one of the stages is the study of the respiratory system.

What disorders of the respiratory system and lungs does the examination show?

Violation of respiratory function occurs in inflammatory, autoimmune, infectious lesions of the lungs. These include:

• COPD and asthma, confirmed and suspected;
• bronchitis, pneumonia;
• silicosis, asbestosis;
• fibrosis;
• bronchiectasis;
• alveolitis.

Features of the FVD method in a child

To check the functioning of the respiratory system, the respiratory system includes several types of samples. During the study, the patient must perform several actions. A child under 4-5 years old cannot fully fulfill all the requirements, therefore, FVD is prescribed after this age. The child is explained what he should do, resorting to a playful form of work. When deciphering the results, you may encounter inaccurate data. This will lead to a false declaration of lung or upper system dysfunction.

Conducting a study in children differs from adults because the pediatric population anatomical structure the respiratory system has its own characteristics.

The initial contact with the child comes to the fore. Among the methods, one should choose the options that are closest to physiological respiration, which do not require significant efforts from the child.

How to properly prepare for the procedure: action algorithm

If you need to prepare to explore the external character of breathing, you do not need to perform complex actions:

• exclude alcohol, drinks, strong tea and coffee;
• a few days before the procedure, limit the number of cigarettes;
• eat before spirometry a maximum of 2 hours;
• avoid active physical activity;
• wear loose clothing for the procedure.

If the patient has bronchial asthma, then compliance with the requirements of medical personnel can lead to an attack. Therefore, preparation can also be considered a warning about a possible deterioration in well-being. Pocket inhaler for emergency assistance should be with him.

Can I eat food before the test?

Although directly digestive system is not related to the respiratory system, but overeating before the study of respiratory function can cause the stomach to compress the lungs. Digestion of food, its movement through the esophagus reflexively affects breathing, speeding it up. Given these factors, there is no need to refrain from food for 6-8 hours, but you should not eat before the examination itself. Optimal time- 2 hours before the procedure.

How to breathe correctly when doing a respiratory tract?

In order for the results of the examination of the function of the respiratory system to be reliable, it is necessary to bring it back to normal. The patient is placed on the couch, where he lies for 15 minutes. Methods for the study of respiratory function include spirography, pneumotachography, body plethysmography, peak flowmetry. The use of only one of the methods does not allow to fully assess the state of the respiratory system. FVD - a set of measures. But most often the first methods of examination from the list are prescribed.

The person's breathing during the procedure depends on the type of examination. With spirometry, lung capacity is measured, for which a person must take a normal breath and exhale into the device, as with normal breathing.

With pneumotachography, the speed of air conduction through the respiratory tract is measured at rest and after exercise. To determine the vital capacity of the lungs, you need to take the deepest possible breath. The difference between this indicator and the volume of the lungs is the reserve capacity.

What sensations does the patient experience during the examination?

Due to the fact that during the diagnostics, the patient is required to use all the reserves respiratory tract may experience slight dizziness. Otherwise, the study does not cause discomfort.

Diagnosis of respiratory organs by spirography and spirometry

During spirometry, the patient sits with his hands in a special place (armrests). Registration of the result is carried out by a special apparatus. A hose is attached to the body, at the end having a disposable mouthpiece. The patient takes it in his mouth, the health worker closes his nose with a clamp.

For some time, the subject breathes, getting used to the changed conditions. Then, at the command of the health worker, he takes a normal breath and releases the air. The second study involves the measurement of expiratory volume after the end of the standard portion. The next measurement is the inspiratory reserve volume, for this you need to draw air as fully as possible.

Spirometry - spirometry with recording the result on a tape. In addition to the graphic image, the activity of the system is displayed in material form. To get a result with a minimum error, it is removed several times.

Other methods for the study of respiratory function

Other methods included in the complex are carried out less frequently and are prescribed in the case when spirometry fails to obtain a complete picture of the disease.

Pneumotachometry

This study allows you to determine the speed of air flow through different parts of the respiratory system. It is carried out on inhalation and exhalation. The patient is asked to inhale or exhale as much as possible into the machine. Modern spirographs simultaneously record spirometry and pneumotachometry readings. It allows you to establish diseases accompanied by a deterioration in the conduction of air through the respiratory system.

Test with bronchodilators

Spirometry does not reveal latent respiratory failure. Therefore, in the case of an incomplete picture of the disease, a FVD with a test is prescribed. It involves the use of bronchodilators after measurements are taken without the drug. The interval between measurements depends on which medicinal substance is used. If it's salbutamol, then after 15 minutes, ipratropium - 30. Thanks to testing with bronchodilators
it is possible to determine the pathology at the earliest stage.

provocative lung test

This option of checking the respiratory system is performed if there are signs of asthma, but the test with a bronchodilator is negative. The provocation is that methacholine is inhaled into the patient. The concentration of the drug is constantly increasing, which provokes difficulty in the conduction of the respiratory tract. There are symptoms of bronchial asthma.

Bodyplethysmography

Body plethysmography is similar to previous methods, but it more fully reflects the picture of the processes occurring in the respiratory system. The essence of the study is that a person is placed in a sealed chamber. The actions that the patient must perform are the same, but in addition to the volumes, the pressure in the chamber is recorded.

Test with ventolin

This drug belongs to the selective agonists of β2-adrenergic receptors, the active substance is salbutamol. When administered after 15 minutes, it provokes the expansion of the bronchi. In the diagnosis of asthma, it is essential: the patient is given spirometry, measuring the parameters of air circulation before and after the drug. If the second test shows an improvement in ventilation by 15%, the test is considered positive, from 10% - doubtful, below - negative.

stress tests

They consist in measuring the performance of the respiratory system at rest and after exercise. Such a test allows you to determine the disease of effort, in which coughing begins after exercise. This is often seen in athletes.

Diffusion test

The main function of respiration is gas exchange, a person inhales oxygen necessary for cells and tissues, removes carbon dioxide. In some cases, the bronchi and lungs are healthy, but gas exchange, that is, the process of gas exchange, is disturbed. The test shows this: the patient closes the nose with a clamp, inhales the mixture of gases through the mask for 3 seconds, exhales for 4 seconds. The equipment immediately measures the composition of the exhaled air and interprets the data obtained.

Deciphering the results of the respiratory function: a table - the norms of indicators for a man, woman and child

Having received the conclusion of the apparatus, it is necessary to analyze the data obtained, to draw a conclusion about the presence or absence of pathology. They should be deciphered only by an experienced pulmonologist.
The run-up in terms of normal indicators is much different, since each person has his own level of physical fitness, daily activity.

The volume of the lungs depends on age: up to 25-28 years, the value of VC increases, by 50 it decreases.

To decipher the data, normal values ​​are compared with those obtained from the patient. For ease of calculation, inspiratory and expiratory volumes are expressed as a percentage of vital capacity.

A healthy person should have a volume of FVC (forced vital capacity), FVC, Tiffno index (FVC / FVC) and maximum voluntary lung ventilation (MVL) of at least 80% of the values ​​indicated as average. If the actual volumes are reduced to 70%, then this is recorded as a pathology.

When interpreting the results of a stress test, the difference in performance, expressed in %, is used. This allows you to visually see the difference between volume and velocity of air. The result can be positive when the patient's condition has improved after the introduction of a bronchodilator, or negative. In this case, the air conduction has not changed, the medicine can adversely affect the condition of the respiratory tract.

To determine the type of violation of air conduction through the respiratory tract, the doctor focuses on the ratio of FEV, VC and MVL. When it is established whether the ventilation capacity of the lungs is reduced, attention is paid to FEV and MVL.

What equipment and devices are used in medicine for testing?

For different types For FVD studies, different devices are used:

1. Spirometer portable with thermal printer SMP 21/01;
2. Spirograph KM-AR-01 "Diamant" - pneumotachometer;
3. Analyzer "Schiller AG", it is convenient to use for samples with bronchodilators;
4. Spiroanalyzer "Microlab" has a touch screen, switching functions is carried out by touching the function icon;
5. Portable spirograph "SpiroPro".

This is only a small part of the devices that record the functions of external respiration. Medical device companies offer portable and stationary devices to institutions. They differ in capabilities, each of the groups has its own advantages and disadvantages. For hospitals and clinics, it is more important to purchase a portable device that can be transferred to another office or building.

Will FVD show asthma in a child and how?

The patient is measured the main indicators, then determine the relationship to the norm. A patient with obstructive disease has a decrease below 80% of the norm, and the ratio of FEV to FVC (Gensler index) is below 70%.

Asthma is characterized by reversible upper airway obstruction. This means that the ratio of FEV / VC after the introduction of salbutamol increases. In order to put asthma, in addition to the respiratory function indicators that indicate pathology, the patient must have Clinical signs violations.

Research during pregnancy and during breastfeeding

When diagnosing diseases, the question always arises whether pregnant and lactating women can be examined. Violations in the functioning of external respiration and the system as a whole can be detected during gestation for the first time. The deterioration of the conductivity of the pathways leads to the fact that the fetus does not receive the required amount of oxygen.

For pregnant women, the rules prescribed in the tables do not apply. This is due to the fact that in order to provide the required volume of air to the fetus, the minute ventilation rate gradually increases, by 70% by the end of the gestational period. The volume of the lungs, the rate of expiration are reduced due to compression of the diaphragm by the fetus.

When examining the function of external respiration, it is important to improve the patient's condition, so if a bronchodilator load is required, then it is carried out. Tests allow you to establish the effectiveness of therapy, prevent the development of complications, start timely treatment. The method is carried out in the same way as in non-pregnant patients.

If the patient has not previously taken drugs for the treatment of asthma, then during lactation it is undesirable to use a test with a bronchodilator. If necessary, the child is transferred to artificial nutrition for the period of drug withdrawal.

What are the normal parameters of respiratory function in COPD and bronchial asthma?

2 violations differ in that the first refers to irreversible types of airway obstruction, the second - to reversible. When a breath test is performed, the specialist is faced with the following results for COPD: VC decreases slightly (up to 70%), but the FEV / 1 rate is up to 47%, that is, the violations are pronounced.

With bronchial asthma, the indicators may be the same, since both diseases are classified as an obstructive type of disorder. But after a test with salbutamol or another bronchodilator, the indicators increase, that is, the obstruction is recognized as reversible. With COPD, this is not observed, then FEV is measured in the first second of exhalation, which gives an idea of ​​the severity of the patient's condition.

Contraindications for the study

There is a list of conditions in which spirometry is not performed:

• early postoperative period;
• malnutrition of the heart muscle;
• thinning of the artery with dissection;
• age over 75;
• convulsive syndrome;
• hearing impairment;
• mental disorder.

The study creates a load on the vessels, pectoral muscles, can increase pressure in different departments and cause a deterioration in well-being.

Are there possible side effects when PVD is performed?

Undesirable effects from the examination are due to the fact that it requires you to exhale quickly into the mouthpiece several times. Due to the excess influx of oxygen, a tingling sensation appears in the head, dizziness, which quickly passes.

If we examine the function with a bronchodilator, then its administration provokes several non-specific reactions: a slight tremor of the limbs, a burning sensation or tingling in the head or body. This is due to the complex action of the drug, which dilates blood vessels throughout the body.

The deterioration of the environmental situation leads to an increase in the proportion of acute and chronic bronchopulmonary diseases. At the beginning of development, they are secretive, therefore invisible. Medicine has improved the method of studying the respiratory function, so that all data is obtained automatically. Preparation does not take much time, and the patient receives the result almost immediately. Every person is interested in taking this study. This may be a guarantee that he is healthy.

Often, doctors prescribe their patients to undergo a respiratory examination. What it is? What results are considered normal? What diseases and disorders can be diagnosed using this method? These questions are of interest to many.

FVD - what is it?

FVD is an abbreviation that stands for "function of external respiration." Such a study allows you to evaluate the work of the respiratory system. For example, with its help, the doctor determines how much air enters the patient's lungs and how much comes out. In addition, during the test, it is possible to analyze the change in air flow velocity in different parts of the respiratory system. Thus, the study helps to assess the ventilation capacity of the lungs.

Importance of FVD for modern medicine

Actually the value this study hard to overestimate. Naturally, it is used to diagnose certain disorders of the respiratory system. But the range of application of the method is much wider. For example, spirometry is a mandatory, regular test for people working in hazardous environments. In addition, the results of this analysis are used for expert evaluation of a person's performance, determining his suitability for work in certain environmental conditions.

The study is used for dynamic monitoring, as it makes it possible to assess the rate of development of a particular disease, as well as the results of therapy. In some cases, the analysis of respiratory function is used to diagnose allergic diseases, because it allows you to trace the effect of a substance on the respiratory tract. In some cases, mass spirometry of the population is carried out in order to determine the health status of residents of certain geographical or ecological zones.

Indications for analysis

Indicators of analyzes in bronchial asthma

Bronchial asthma- refers to chronic diseases, a sign of which is an asthma attack resulting from swelling of the bronchial mucosa and spasm of smooth muscles.

non-infectious allergens (substances that cause allergic reactions):
. pollen
. medications
. insect bites
. food products, etc.

infectious allergens:
. viruses
. bacteria
. mushrooms

chemical substances:
. alkalis
. acids

physical factors:
. air temperature changes
. atmospheric pressure changes
. stressful influences

Hereditary genetic predisposition, certain working and living conditions, past viral respiratory and allergic diseases can also predispose to the development of bronchial asthma.

The main manifestation of bronchial asthma is an asthma attack (usually at night), which lasts from several minutes to several days.
The inhalation becomes short and the exhalation long.
Worrying cough, shortness of breath. During the period of suffocation, a cough with viscous sputum that is difficult to separate, the amount of sputum at the end of the attack increases, and it leaves more easily ("vitreous sputum").

Inflammation and obstruction of the airways in asthma

Indicators of laboratory research

General blood analysis. One of the signs of the disease is eosinophilia, which is more pronounced with frequent attacks; in some cases, eosinophilia can be observed immediately before an attack, and after an attack and in remission, eosinophilia may be absent.
Increased rates hemoglobin and erythrocytes appear with the development of insufficiency of external respiration. ESR is moderately increased.

Research in bronchial asthma. Examination of the function of external respiration (PVD)

For diagnosis of bronchial asthma. for dynamic monitoring of patients and evaluation of the effectiveness of therapy, indicators of the expiratory rate are recorded. Such studies are especially useful when the patient does not have asthma symptoms or signs of difficulty breathing.

Air flow rate and lung volumes are recorded by spirometry during forced exhalation. Airflow limitation in asthma causes smaller partial expiratory volumes of the lungs. Spirometric target values ​​for OOB1 have been developed for children of different heights, genders, and ethnicities. The decrease in FEV1, expressed as a percentage of the standard value, is one of the four criteria for the severity of bronchial asthma.

Since sick the lungs are usually swollen, and often very much, the ratio of FEV1 to FVC allows you to calculate their total expiratory volume. A FEV1/FVC ratio less than 0.8 usually indicates severe airflow limitation. However, it is impossible to diagnose bronchial asthma only on the basis of a decrease in airflow rate, since this is also characteristic of many other pathological conditions. In bronchial asthma, inhalation of β-agonists (for example, salbutamol through a nebulizer) dilates the bronchi more than in the absence of asthma; asthma is characterized by an increase in FEV1 by more than 12%.

It is important to remember that diagnostic value of spirometry data depends on the patient's ability to repeated full and forced expiration. Children over 6 years of age usually perform this procedure easily. Spirometry data are only relevant if they are reproducible over the course of the study. If, with three consecutive attempts, FEV1 differs by no more than 5%, then they are guided by the best of the three indicators.

Solopov V.N. Asthma. Evolution of the disease

Examination of the function of external respiration

a. Respiratory disorders in bronchial asthma are caused by reversible airway obstruction, which is manifested primarily by a decrease in FEV 1 and peak volumetric velocity. These indicators usually quickly normalize after the use of bronchodilators (see Fig. 7.3). An increase in FEV 1 after the use of bronchodilators by more than 20% indicates reversible bronchospasm. With blockage of the bronchi by mucous plugs and swelling of the mucous membrane, the action of bronchodilators is slower. It should be remembered that the absence of a significant increase in FEV 1 after the use of bronchodilators does not exclude the diagnosis of bronchial asthma. Lack of response may be due to the following reasons: 1) no obstruction or minor airway obstruction in the interictal period, 2) the action of bronchodilators used shortly before the study, 3) improper use of inhaled bronchodilators, 4) bronchospasm caused by irritants that make up the composition inhaled bronchodilators, 5) bronchospasm caused by diagnostic procedures especially spirometry.

1) In the interictal period, FEV 1 is usually normal. Indicators of FEV 1 and peak volumetric velocity reflect the state of the large bronchi. With narrowing of small (less than 2-3 mm in diameter) bronchi, FEV 1 and peak volumetric velocity are often normal (FEV 1 is reduced only with severe obstruction of small bronchi). To assess the state of small bronchi, another indicator is used - the average volumetric velocity of the middle of exhalation. To determine it, a graph of the dependence of the air flow on the forced expiratory volume is plotted - the flow-volume curve (see Fig. 7.3). It should be remembered that an isolated decrease in the average mid-expiratory volume velocity can also be observed in the interictal period.

2012-11-02 13:17:58

Maria asks:

Hello! For 2 months, she has had a dry cough, a feeling of a lump somewhere in the trachea, just below the throat. She underwent an examination, did an analysis for IgE - the norm, eosinophils in the blood are normal (2). On x-ray chest without changes. FVD revealed latent bronchospasm. Based on this, the doctor diagnosed me with bronchial asthma. I bought a peak flow meter, I have been taking measurements in the morning and in the evening every day for 8 days now. For my age and weight, the norm is 393, my indicators are usually 450-470. There are no so-called "morning dips" in the peak flow chart. Please tell me, maybe I just did the FVD wrong? Recently, the cough has greatly decreased, but there is a feeling of wheezing in the left lung at the bottom when coughing, with a simple inhalation and exhalation it is gone. I was advised to contact a psychologist, I began to consult with him. There were no asthma attacks. Prolonged rise in temperature 37-37.2. What could it be?

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For normal life human body air is needed.

Saturation of cells with oxygen is the main purpose of the respiratory system.

The volume of air inhaled is important in determining the level of lung function. For this kind of research, there is spirometry.

What it is, for what purpose, how it is carried out and when its appointment is excluded will be discussed later in the article.

The essence of spirometry

The term is formed from two words: spiro- breathing and metria- measurements, measurements.

Spirometry – diagnostic examination functions of external respiration with the establishment of characteristic speed and volume indicators.

The method is widely used in medicine: it allows you to identify pathologies that cause, low level gas exchange.

The procedure is painless and harmless. Measurements are based on the frequency of inhalations and exhalations, lung capacity.

The procedure is carried out with a special digital device - a spirometer. Their mechanism is quite simple: an airflow sensor and a computational part that converts information into numerical values.

Readings are calculated automatically. There are computer modifications of the device.

The first examinations were carried out with mechanical (most often water) spirometers. All indicators were calculated manually. The procedure was long and laborious.

If you need constant monitoring, you can use a modern portable spirometer, which is applicable both at home and when traveling.

The consultation of the attending physician and medical specialist sales of similar equipment. The spirometer is selected taking into account functional requirements and personal preferences.

The most accurate measurements are given by a special camera with sensors - plethysmograph. The results of the study, presented graphically in the form of spirography, help to clearly illustrate the changes in human lung volume during normal and enhanced breathing. What is spirography and how it looks can be clearly seen in the figure:

Through the procedure:

• diagnose pathological abnormalities (foci of impaired gas exchange, the level of bronchial obstruction);
• assess the patient's condition during treatment and the effectiveness of therapy;
• teach various breathing techniques.

Measurements are performed on an outpatient basis with immediate results.

Reasons for an examination

There are a number of indications for the appointment of the procedure. Diagnostics is carried out in order to:

• studies of frequent acute respiratory infections,;
• detection of pathological disorders of the respiratory system with a prolonged cough, respiratory failure, sputum production, pain behind the sternum;
• identifying the causes of deviations in the gas exchange process;
• analysis of the relationship between pulmonary diseases and the function of external respiration, the effectiveness of therapeutic measures in their treatment;
• prevention and early detection of abnormalities in individuals with an increased risk of developing pathologies: smokers and persons whose labor activity associated with harmful substances;
• monitoring of the course of bronchopulmonary diseases:
  • asthma;
  • etc.;
• acute allergic manifestations ();
• calculation of indicators for the establishment of disability and the level of ability to work;
• preparation of patients for operations of the broncho-pulmonary system;
• selection of suitable drugs for bronchial dilatation.

Persons over the age of 40, smokers for 10 years or more, with chronic cough or examination is mandatory.

Preventive medical measures are recommended for workers associated with the regular use of harmful chemicals.

Contraindications for spirometry

Spirometry has no strict contraindications. Mild dizziness, which may occur, passes quickly and does not pose a health hazard.

Forced or strong deep inspiration causes a short-term increase in intracranial and intra-abdominal pressure.

With caution, carry out or refuse the procedure for the following indications:

• recent transactions in abdominal organs or ophthalmic surgical procedures (less than 2 months ago);
• or (depending on the patient's condition, but not earlier than 3 months after them);
• past respiratory tract infections (at least 2 weeks after their curation);
• presence in history;
• arterial or aortic aneurysm;
• severe seizures;
• the presence of pulmonary bleeding;
• epilepsy;
• and other pathologies associated with a violation of pressure;
• increased blood clotting;
• mental disorders;
• pregnancy;
• age restrictions: up to 5 and after 75 years.

Even in the absence of obvious contraindications, it is necessary to consult a specialist before the study.

Spirometry classification

How the procedure is carried out determines its appearance. Spirometry tests are done with the following maneuvers:

• normal calm breathing;
• exhale with effort (forced);
• with maximum ventilation of the lungs;
• With physical activity(before and after it) - dynamic spirometry;
• with the use of special substances - functional and provocative spirometry:
  • With bronchodilators dilating the bronchi. The method helps to identify hidden bronchospasms, correctly diagnose the disease, determines the reversibility of disorders and the effectiveness of therapeutic techniques;
  • With methacholine helping to definitively diagnose asthma, identify predisposition to bronchospasm and hyperreactivity.

Modern spirometers make it possible to determine the level of diffusive capacity of the lungs - the gas exchange of oxygen and carbon dioxide between the respiratory organs and the blood.

An additional examination is bronchospirometry. Allows you to separately fix the indicators in different lobes of the lungs.

Preparatory activities

Preparation for spirography is very important. The reliability of the results obtained is increased if the following rules are observed:

• the study should be done on an empty stomach or at least 2 hours after eating a light meal in the morning;
• one day before the examination, stop smoking (or at least 4 hours in advance), reduce the consumption of caffeinated drinks, do not drink alcohol;
• refuse drugs that can distort the performance;
• free and comfortable clothes, not interfering with breathing;
• half an hour before measurements to be at rest, breathe calmly;
• a patient who uses an inhaler takes it to the procedure;
• bring a handkerchief or napkins with you.

Before starting the study, the medical officer must find out the patient's data (height, weight) and enter their device, select the spirometer by size, help the patient take the desired position and explain the sequence and rules for performing breathing maneuvers.

Performing a procedure

The patient is in a comfortable position, hands on the armrests are relaxed. To ensure only oral breathing, the nose is blocked with a special clip. A tube with a disposable sterile tip (mouthpiece) is inserted into the mouth. At the beginning of the procedure, the patient breathes naturally, evenly.

The DO indicator is determined - the respiratory volume. The patient is then asked to take a normal breath and completely exhale all the air as quickly as possible. This will be the expiratory reserve volume (ERV).

The duration of exhalation with a maximum effort of more than 15 seconds is a reason for diagnosing pathology. Then the maximum breathing capacity is measured.

The deepest breath follows (reserve inspiratory volume is fixed - ROV and vital capacity - VC) and rapid exhalation (FEV and FVC are determined).

The device automatically builds a graph based on measurements. FEV indicators have diagnostic significance.

The shape of the depicted loop allows you to diagnose the type of respiratory failure:

• obstructive;
• restrictive;
• mixed.

The reversibility of the obstruction is determined by the data of the test with bronchodilators. It is the readings of the FEV that are of primary comparative importance.

Each test is carried out several times (usually 3 times). After that, the most successful of them are selected.

The device gives the result of the spirogram, according to which the doctor evaluates the specific case and makes a conclusion. The procedure takes about 15 minutes. How many times, with what frequency to carry out diagnostics is determined by the attending pulmonologist according to indications.

Spirometry Data

The result of the survey is evaluated according to the following indicators:

• VC - vital capacity of the lungs, calculated as the difference between the volume of air during full inspiration and full exhalation;
• FVC - forced vital capacity of the lungs. Reflects the maximum volume of exhaled air (FEV) at maximum inspiration. It makes it possible to fix the elasticity of the lung tissue and the excursion of the chest, that is, restrictive violations;
• FEV1 - forced expiratory volume in the first second, usually expressed as a percentage of FEV. The most informative indicator of spirometry. Demonstrates the speed of passage of air in the bronchi. For a final understanding of the pathological process (bronchial obstruction or restriction of the lung parenchyma), the following parameter is calculated;
• Tiffno index - the ratio of FEV1 and FVC parameters in percent. Normally, it is from 70%. Deviations are due to:
  • decrease in FEV1 - disease with obstruction;
  • a decrease in FVC with an unchanged or slightly reduced FEV1 indicator - a change in the elasticity of the lung tissues.

Table 1. Abbreviated designation and characteristics of indicators of spirometric research.

Examination for young patients

From the age of 9, a full examination is possible along with adults. Small patients should be diagnosed in specialized institutions for children.

Creating a relaxed atmosphere is the key to successful spirometry. An employee with a pedagogical approach and the use of a playful form has more authority in the eyes of the child and will be able to carry out the procedure most effectively.

The meaning of the event and its actions are explained to the child. Thematic pictures can be used to allow the child to understand what is required. For example, blow out a candle.

The specialist should pay attention to the correctness of the maneuvers, the correct hermetic girth of the tube with the lips. The protocol reflects the number of successful tests. When forming the conclusion, the age of the patient is taken into account.

Deciphering the result of FVD

There are certain norms of indicators, based on which the doctor draws conclusions.

The interpretation of the results of the respiratory function should take into account the sexual anatomical differences, age-related changes, past illnesses, type of work activity.

The indicators will be differentiated for a healthy person and a patient. The formulas for calculating the norm are given in the table:

Table 2. Formulas for calculation normal indicators spirometry

Note. When using a SG spirometer, the due FEV1 decreases in men by 0.19 liters, in women - by 0.14 liters. In persons aged 20 years, VC and FEV are approximately 0.2 liters less than at the age of 25 years; in persons over 50 years old, the coefficient when calculating the due MVL is reduced by 2.

For each person, the norm will be individual. Main spirometric parameters: FEV1, VC, FVC, FEV1/FVC. The results are analyzed by the maximum values ​​of FVC and FEV1.

The interpretation of the data obtained should be concise, clear, and complete. The specialist not only determines the deviations of indicators from the normative value, but also evaluates the overall picture, analyzing their entire set in interconnection.

All indicators are presented below:

Table 3 Spirometry indicators

The Tiffno test is informative in assessing pathological abnormalities. To understand the degree of deviation from the norm, it is customary to determine the percentage. Depending on the decrease in the indication, the severity of pathological abnormalities increases.

A 70% FEV1/FVC ratio results in significant false positives, and a reading of 80% also often misinterprets the result in adults but is acceptable in children. For people more old age(over 70 years old) some experts recommend using a value of 65%.

Carrying out the procedure with a high-quality spirometer will avoid distortion and obtain reliable readings.

Correct interpretation of the results of respiratory function helps to diagnose diseases on early stages, prevent the development severe forms, to determine the effectiveness of drugs in the treatment of respiratory disorders.

Correctly performed spirometry, taking into account all individual features The patient provides comprehensive information about the state of the respiratory system. Painless, easy procedure, immediate results, no side effects– undeniable advantages of this type of diagnostics.

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Indicators of the function of external respiration

Indicators of the function of external respiration

To characterize the function of external respiration, such basic concepts as tidal volumes and lung capacities are used.

There are the following tidal volumes(Fig. 7):

Tidal volume(DO) - the volume of gas inhaled and exhaled during quiet breathing.

Inspiratory reserve volume(RO vd) - the maximum amount of gas that can be additionally inhaled after a quiet breath.

expiratory reserve volume(RO vyd) - the maximum amount of gas that can be additionally exhaled after a quiet exhalation.

Residual lung volume(OOL) - the volume of gas remaining in the lungs after a maximum exhalation.

Rice. 7. Tidal volumes and lung capacities

lung capacity consist of lung volumes (Fig. 7):

Vital capacity of the lungs(VC) - the maximum volume of gas that can be exhaled after the deepest breath possible. It is the sum of tidal volume + inspiratory reserve volume + expiratory reserve volume.

Inspiratory capacity(E vd) - the maximum volume of gas that can be inhaled after a quiet exhalation. It is the sum of tidal volume + inspiratory reserve volume.

Functional residual capacity(FOE) is the volume of gas remaining in the lungs after a quiet exhalation. It is the sum of residual lung volume + expiratory reserve volume.

Total lung capacity(TEL) is the total amount of gas contained in the lungs after a maximum inspiration. It is the sum of tidal volume + inspiratory reserve volume + expiratory reserve volume + residual lung volume.

Fine healthy man can exhale 80-85% of the vital capacity (VC) at a high rate, and the rest is exhaled slowly. With various pathological conditions when there is a narrowing of the lumen of the bronchi, the resistance to airflow during exhalation increases, and a smaller amount of VC is exhaled at a high speed. The narrower the lumen of the bronchi (which occurs in bronchial asthma), the lower the speed of air passing through them, the lower the percentage of VC is able to exhale the patient at a high speed. To assess the degree of bronchial constriction, analyze the indicators determined when breathing at the highest possible speed. These indicators include:

forced vital capacity(FVC) - the volume of air exhaled during the most rapid and strong exhalation.

Forced expiratory volume in 1 s(FEV 1) - the amount of air removed from the lungs in the first second of exhalation. The ratio of forced expiratory volume in 1 s (FEV 1) to forced vital capacity (FVC) - Tiffno index(FEV 1 / FVC).

Instantaneous Volumetric Output Rate(MOS) - the speed of the air flow at the moment of exhalation of a certain proportion of the forced vital capacity of the lungs - 25, 50 and 75%. Designated MOS 25%, MOS 50%, MOS 75%.

Peak expiratory volume flow(PSV) - the maximum volumetric forced expiratory flow rate.

All of the above indicators are measured using special devices - spirometers, the study itself is called spirometry.