Inhalation and exhalation for a person is not just a physiological process. Remember how we breathe in different life circumstances.

Fear, anger, pain - breathing is constricted and constrained. Happiness – there are not enough emotions to show joy – we breathe deeply.

Another example with the question: how long can a person live without food, sleep, or water? And without air? It’s probably not worth continuing talking about the importance of breathing in a person’s life.

Breathing - Quick Facts

The ancient Indian teaching of yoga states: “Human life is the temporary periods between inhalation and exhalation, for these movements, saturating all cells with air, ensure his very existence.”

A man who breathes half lives also lives half. We are, of course, talking about unhealthy or improper breathing.

How can you breathe incorrectly, the reader will object, if everything happens without the participation of consciousness, so to speak “automatically”. The smart guy will continue - breathing is controlled by unconditioned reflexes.

The truth lies in psychological trauma and all kinds of diseases that we accumulate throughout our lives. They are the ones who make the muscles tense (overstrained) or, conversely, lazy. Therefore, over time, the optimal mode of the respiratory cycle is lost.

It seems to us that ancient man did not think about the correctness of this process; nature itself did it for him.

The process of filling human organs with oxygen is divided into three components:

1. Clavicular (upper). Inhalation occurs due to the upper intercostal muscles and clavicles. Try it to make sure that this mechanical movement does not completely expand the chest. Little oxygen is supplied, breathing becomes frequent and incomplete, dizziness occurs and the person begins to choke.
2. Middle or chest. With this type, the intercostal muscles and the ribs themselves are activated. The chest expands to its maximum, allowing it to be completely filled with air. This type is typical under stressful circumstances or mental stress. Remember the situation: you are excited, but as soon as you take a deep breath, everything disappears somewhere. This is the result of proper breathing.
3. Abdominal diaphragmatic breathing. This type of breathing, from an anatomical point of view, is the most optimal, but, of course, not entirely comfortable and familiar. You can always use it when you need to relieve mental stress. Relax your abdominal muscles, lower your diaphragm to the lowest position, then return it back to the starting position. Please note, there was a calm in the head, thoughts became clearer.

Important! By moving the diaphragm, you not only improve your breathing, but also massage the abdominal organs, improving metabolic processes and food digestion. Thanks to the movement of the diaphragm, blood supply to the digestive organs and venous outflow are activated.

This is how important it is for a person not only to breathe correctly, but also to have healthy organs that ensure this process. Constant monitoring of the condition of the larynx, trachea, bronchi, and lungs greatly contributes to solving these problems.

Pulmonary function test

FVD in medicine, what is it? To test the functions of external respiration, a whole arsenal of techniques and procedures is used, the main task of which is to objectively assess the condition of the lungs and bronchi, as well as autopsy at an early stage of the development of pathology.

The gas exchange process that occurs in the tissues of the lungs, between blood and outside air penetrating into the body, is called external respiration by medicine.

Research methods that allow diagnosing various pathologies include:

1. Spirography.
2. Body plethysmography.
3. Study of the gas composition of exhaled air.

Important! The first four methods of analysis of respiratory function allow you to study in detail the forced, vital, minute, residual and total lung volume, as well as the maximum and peak expiratory flow. While the gas composition of the air leaving the lungs is studied using a special medical gas analyzer.

In this regard, the reader may have the false impression that FVD examination and spirometry are one and the same. Let us emphasize once again that the study of respiratory function is a whole set of tests, which includes spirometry.

Indications and contraindications

There are indications for comprehensive testing of upper respiratory functions.

These include:

1. Patients, including children, who exhibit: bronchitis, pneumonia, emphysema of pulmonary tissue, nonspecific lung diseases, tracheitis, rhinitis in various forms, laryngotracheitis, damage to the diaphragm.
2. Diagnosis and control of COPD (chronic obstructive pulmonary disease).
3. Examination of patients involved in hazardous production areas (dust, varnishes, paints, fertilizers, mines, radiation).
4. Chronic cough, shortness of breath.
5. Examination of upper breathing in preparation for surgical operations and invasive (taking living tissue) examinations of the lungs.
6. Examination of chronic smokers and people prone to allergies.
7. Professional athletes, in order to determine the maximum capabilities of the lungs under increased physical activity.

At the same time, there are restrictions that make it impossible to conduct a survey due to certain circumstances:

1. Aneurysm (protrusion of the wall) of the aorta.
2. Bleeding in the lungs or bronchi.
3. Tuberculosis in any form.
4. Pneumothorax is when a large amount of air or gas accumulates in the pleural area.
5. Not earlier than a month after surgery on the abdominal or thoracic cavity.
6. After a stroke or myocardial infarction, the study is possible only after 3 months.
7. Intellectual retardation or mental disorders.

Video from an expert:

How is the research conducted?

Despite the fact that the FVD study procedure is a completely painless process, in order to obtain the most objective data, it is necessary to carefully approach its preparation.

1. FVD is done on an empty stomach and always in the morning.
2. Smokers should abstain from cigarettes four hours before the test.
3. On the day of the study, physical activity is prohibited.
4. For asthmatics, avoid inhalation procedures.
5. The subject should not take any drugs that dilate the bronchi.
6. Do not drink coffee or other caffeinated tonic drinks.
7. Before the test, loosen clothing and its elements that restrict breathing (shirts, ties, trouser belts).
8. In addition, if necessary, follow additional recommendations made by your doctor.

Research algorithm:

If there is a suspicion of obstruction that impairs the patency of the bronchial tree, an FVD with a test is performed.

What is this test and how is it done?

Spirometry in the classic version provides a maximum, but incomplete, picture of the functional state of the lungs and bronchi. Thus, in case of asthma, a breathing test using a machine without the use of bronchodilators, such as Ventolin, Berodual and Salbutamol, is not able to detect hidden bronchospasm and it will go unnoticed.

Preliminary results are ready immediately, but they still need to be deciphered and interpreted by a doctor. This is necessary to determine the strategy and tactics for treating the disease, if one is detected.

Decoding of FVD results

After all the test activities have been completed, the results are entered into the spirograph’s memory, where they are processed using software and a graphical drawing is constructed - a spirogram.

The preliminary output generated by the computer is expressed as follows:

• norm;
• obstructive disorders;
• restrictive disorders;
• mixed ventilation disorders.

After deciphering the indicators of external respiration function, their compliance or non-compliance with regulatory requirements, the doctor makes a final verdict regarding the patient’s health condition.

The studied indicators, the norm of respiratory function and possible deviations are presented in a general table:

Indicators	Norm (%)	Conditional rate (%)	Mild impairment (%)	Average degree of impairment (%)	Severe degree of impairment (%)
FVC – forced vital capacity of the lungs	≥ 80	79.5-112.5 (m)	60-80	50-60	< 50
FEV1/FVC – modified. Tiffno index (expressed in absolute value)	≥ 70	84.2-109.6 (m)	55-70	40-55	< 40
FEV1 – forced expiratory volume in the first second	≥ 80	80.0-112.2 (m)	60-80	50-60	< 50
MOS25 - maximum volumetric flow rate at 25% of FVC	> 80	70-80	60-70	40-60	< 40
MOS50 – maximum volumetric flow rate at 50% of FVC	> 80	70-80	60-70	40-60	< 40
SOS25-75 – average volumetric velocity of expiratory flow at the level of 25-75% of FVC	> 80	70-80	60-70	40-60	< 40
MOS75 – maximum volumetric flow rate at 75% of FVC	> 80	70-80	60-70	40-60	< 40

Important! When deciphering and interpreting FVD results, the doctor pays special attention to the first three indicators, because it is FVC, FEV1 and the Tiffno index that are diagnostically informative. Based on the relationship between them, the type of ventilation disturbance is determined.

This unpronounceable name was given to an examination method that allows you to measure the peak volumetric flow rate during a forced (maximum force) exhalation.

Simply put, this method allows you to determine at what speed the patient exhales, making maximum effort. This checks for narrowing of the respiratory channels.

Patients suffering from asthma and COPD especially need peak flowmetry. It is she who is able to obtain objective data on the results of the therapeutic measures carried out.

A peak flow meter is an extremely simple device consisting of a tube with a graduated scale. How is it useful for individual use? The patient can independently take measurements and prescribe the dosage of medications taken.

The device is so simple that even children, not to mention adults, can use it. By the way, some models of these simple devices are produced especially for children.

How is peak flowmetry performed?

The testing algorithm is extremely simple:

How to interpret the data?

Let us remind the reader that peak flowmetry, as one of the methods for studying pulmonary respiratory function, measures peak expiratory flow (PEF). For correct interpretation, you need to identify three signal zones for yourself: green, yellow and red. They characterize a certain range of PSV, calculated based on maximum personal results.

Let's give an example for a conditional patient using a real technique:

1. Green zone. In this range are values ​​indicating remission (weakening) of asthma. Anything above 80% PEF characterizes this condition. For example, a patient’s personal best PSV is 500 l/min. Let's do the calculation: 500 * 0.8 = 400 l/min. We get the lower border of the green zone.
2. Yellow zone. It characterizes the beginning of the active process of bronchial asthma. Here the lower limit will be 60% of the PSV. The calculation method is identical: 500 * 0.6 = 300 l/min.
3. Red zone. Indicators in this sector indicate an active exacerbation of asthma. As you can imagine, all values ​​below 60% of PSV are in this danger zone. In our “virtual” example this is less than 300 l/min.

A non-invasive (without penetration) method of studying the amount of oxygen in the blood is called pulse oximetry. It is based on a computer spectrophotometric assessment of the amount of hemoglobin in the blood.

There are two types of pulse oximetry used in medical practice:

In terms of measurement accuracy, both methods are identical, but from a practical point of view, the second is the most convenient.

Areas of application of pulse oximetry:

1. Vascular and plastic surgery. This method is used to saturate oxygen and control the patient’s pulse.
2. Anesthesiology and resuscitation. It is used while moving the patient to fix cyanosis (blue discoloration of the mucous membrane and skin).
3. Obstetrics. To record fetal oximetry.
4. Therapy. The method is extremely important for confirming the effectiveness of treatment and for fixing apnea (breathing pathology that threatens to stop) and breathing failure.
5. Pediatrics. Used as a non-invasive tool for monitoring the condition of a sick child.

Pulse oximetry is prescribed for the following diseases:

• complicated course of COPD (chronic obstructive pulmonary disease);
• obesity;
• cor pulmonale (enlargement and expansion of the right chambers of the heart);
• metabolic syndrome (a complex of metabolic disorders);
• hypertension;
• hypothyroidism (disease of the endocrine system).

Indications:

• during oxygen therapy;
• insufficient breathing activity;
• if hypoxia is suspected;
• after prolonged anesthesia;
• chronic hypoxemia;
• during the postoperative rehabilitation period;
• apnea or prerequisites for it.

Important! With blood normally saturated with hemoglobin, the figure is almost 98%. At a level approaching 90%, hypoxia is stated. The saturation rate should be about 95%.

Blood gas study

In humans, the gas composition of the blood is usually stable. Pathologies in the body are indicated by shifts in this indicator in one direction or the other.

Indications:

1. Confirmation of the patient's pulmonary pathology, the presence of signs of acid-base imbalance. This manifests itself in the following diseases: COPD, diabetes mellitus, chronic renal failure.
2. Monitoring the patient’s state of health after carbon monoxide poisoning, with methemoglobinemia - a manifestation of an increased level of methemoglobin in the blood.
3. Monitoring the condition of a patient who is connected to forced ventilation.
4. The anesthesiologist needs the data before performing surgical operations, especially on the lungs.
5. Determination of acid-base disorders.
6. Assessment of the biochemical composition of blood.

The body's response to changes in blood gas components

Acid-base balance pH:

• less than 7.5 – the body is oversaturated with carbon dioxide;
• more than 7.5 – the amount of alkali in the body is exceeded.

Oxygen partial pressure level PO 2: drop below normal value< 80 мм рт. ст. – у пациента наблюдается развитие гипоксии (удушье), углекислотный дисбаланс.

Partial pressure level of carbon dioxide PCO2:

1. The result is below the normal value of 35 mmHg. Art. – the body feels a lack of carbon dioxide, hyperventilation is not carried out in full.
2. The indicator is above normal 45 mm Hg. Art. – there is an excess of carbon dioxide in the body, the heart rate decreases, and the patient is overcome by an inexplicable anxious feeling.

Bicarbonate HCO3 level:

1. Below normal< 24 ммоль/л – наблюдается обезвоживание, характеризующее заболевание почек.
2. An indicator above the normal value > 26 mmol/l - this is observed with excessive ventilation (hyperventilation), metabolic alkalosis, and overdose of steroid substances.

The study of respiratory function in medicine is the most important tool for obtaining deep generalized data on the state of the human respiratory organs, the influence of which on the entire process of his life and activity cannot be overestimated.

The world community notes a steady increase in bronchopulmonary diseases, including obstructive variants. Official statistics indicate an almost doubling of cases of detection of bronchial asthma and chronic obstructive pulmonary disease (COPD). According to unofficial data, there are much more cases of pathology - many are in no hurry to seek medical help, preferring to fight the pathology on their own. Pulmonary function (RPF) testing is the easiest way to identify these diseases.

Pulmonary function analysis

This is especially important for people of working age - bronchopulmonary diseases, in the absence of adequate treatment, often cause disability in patients. In clinical practice, broncho-obstructive syndrome is often combined with other pathologies - arterial hypertension, coronary insufficiency, arrhythmias of various origins, and endocrine disorders. The study of respiratory function (pulmonary function) is the simplest and most reliable way to identify bronchopulmonary pathologies in the early stages.

Indications for prescribing an examination

Despite the fact that the FVD study is carried out quickly and does not harm health, it has clear indications and some limitations. Today, the following methods for studying the function of external respiration are used: spirometry and pneumotachography. Patients are referred for examination in the following cases:

• suspicion of bronchopulmonary diseases (asthma, pneumonia) - prolonged cough that cannot be treated, pain, shortness of breath, sputum with an unpleasant odor;
• assessing the impact of the current disease on the lungs;
• preventive examinations of people at risk - experienced smokers, workers in hazardous industries;
• ongoing monitoring of the course of lung disease, incl. assessment of the effectiveness of the treatment;
• disability examination;
• preparing the patient for operations on the lungs or bronchi;
• choosing the optimal bronchodilator for the treatment of the underlying disease;
• in sports to determine how well an athlete tolerates current physical activity.

The ease of such examination and its low cost allow every person to undergo it regularly.

Study of external respiration function using a spirograph

Self-monitoring, carried out at least once a year, is especially indicated for experienced smokers and workers in hazardous industries. After 40-50 years, such an examination is recommended for everyone.

When is FVD testing not prescribed?

Regardless of the specific technique, such a study has certain limitations and is not prescribed in the following cases:

• severe airway obstruction;
• acute myocardial infarction, and for three months after it;
• acute cerebrovascular accident of any type;
• aortic aneurysm;
• acute respiratory tract infections (RTI) and 2 weeks after them;
• pregnancy;
• hypertensive crisis;
• epilepsy.

How to properly prepare for the examination?

Preparation for spirometry does not require compliance with complex conditions. The day before the examination, alcohol, strong tea and coffee are excluded; if possible, it is recommended to limit smoking. If a person is taking medications that affect the functioning of the bronchopulmonary system, their doctor should be informed about this in advance. The last meal should be 2 hours before the test. The rest of the preparation for the study of external respiration function begins directly in the medical institution.

Before carrying out the necessary tests, the patient must be in a quiet environment for half an hour, with the exception of active physical exercise. Clothing should be loose enough to not restrict movement or the chest. If you have bronchial asthma, you should have your inhaler with you, as well as a clean handkerchief. As you can see, the method of preparing for the study of external respiration function allows you to correctly fulfill all the conditions, even for patients in serious condition.

How is the research going?

Before the pulmonary function test is performed, the patient is in a supine position for less than 15 minutes. During this time, breathing returns to normal, after which the examination itself begins. It can be performed using two methods: spirography and pneumotachography.

The first method is a graphical recording of changes occurring in a person’s lungs when performing various breathing maneuvers. Pneumotachography allows you to record the volumetric velocity of air flow during quiet breathing and during physical activity. Spirometric equipment currently used makes it possible to simultaneously record pneumotachometer and spirographic indicators (maximum ventilation and indicators of functional tests) in the patient, which simplifies and speeds up the examination. In some cases, spirometry with a bronchodilator is indicated - this study helps to accurately determine the presence of pathology and prevent its development.

Modern spirograph

FVD spirometry is performed with the patient in a sitting position, with the arms placed on special armrests. A disposable mouthpiece is placed on the device, which the patient takes into the mouth, and a clip is placed on the nose. The doctor asks the person to take a normal or slightly deeper breath, and then calmly release all the air through the mouthpiece. This determines the tidal volume - the amount of air inhaled by a person in everyday life every day.

Subsequently, the reserve volume of exhalation is recorded - when exhaling with maximum effort. Next, the patient must inhale as fully as possible - indicators of the vital capacity of the lungs and the inspiratory reserve volume are obtained. As a rule, the external respiration function requires several “approaches”, which provides extremely accurate indicators. Subsequently, the doctor evaluates the resulting graphs and forms a conclusion.

Bronchodilator study

Spirometry with preliminary administration of bronchodilators is necessary when it is difficult to make an accurate diagnosis, as well as to assess the degree of effectiveness of a particular drug. Initially, the study takes place as usual, without exposure to the drug. After fixing all the necessary indicators, the patient is given the selected drug, and fixing the FV indicators is repeated.

Pulmonary function tests may be performed before and after inhalation of a bronchodilator.

When using salbutamol-based products, measurements are repeated at intervals of 15 minutes. If a drug based on ipratropium bromide is used, the interval between measurements is about half an hour. In some cases, measurements are preceded by physical activity, but the first data recording is always carried out at rest. Since most complex disorders of respiratory function cannot be determined only by external signs, all data obtained is entered into a special computer, where it is processed by special software. Studying the functions of external respiration with bronchodilators helps to identify dangerous pathologies at the earliest stages.

Before the study, taking any medications containing stimulants is strictly prohibited. They affect not only the cardiovascular but also the pulmonary system, which can lead to distorted data and incorrect diagnosis.

Interpretation of results

Spirographic curve

The study of external respiration function, the norm of which differs depending on the age and gender of the patient, allows one to diagnose the main diseases of the bronchopulmonary system with sufficient accuracy. One of the most dangerous disorders is airway obstruction. This will be indicated by a decrease in expiratory force and vital capacity of the lungs. Obstruction may indicate the presence of bronchial asthma, acute bronchitis with an asthmatic component, as well as chronic obstructive bronchitis. The doctor gives the transcript to the patient after analysis and diagnosis.

FVD study is carried out to diagnose lung diseases and their dynamic monitoring. Based on such a study, it is possible to assess the impact of existing diseases on the state of the respiratory system, predict the development of complications, and also establish the reversibility of pathological changes.

There are factors that affect healthy breathing that can lead to serious lung disease and airway obstruction due to spasm, swelling, or blockage by thick mucus or foreign matter.

Namely:

One of the methods for assessing external respiration is spirography. This is a modern way of accurate, highly informative and non-invasive study of the ventilation function of the lungs.

• a cough that lasts more than 3-4 weeks after ARVI and acute bronchitis, as well as a lingering cough for no reason,
• periodic shortness of breath,
• difficulty breathing,
• feeling of lack of air,
• feeling of chest congestion,
• wheezing and wheezing, mainly when exhaling, but also at night and in the early morning hours,
• long smoking history,
• frequent colds (bronchitis, ARVI),
• heredity (COPD, allergic diseases in relatives),
• diagnosed bronchial asthma (for treatment correction).

A spirographic study allows one to detect the patient’s existing disease among the variety of disorders of the lungs, bronchi and lung tissue. Spirography is a painless procedure that is performed within a few minutes in an outpatient setting. To obtain the most reliable results, preparation for the procedure is necessary:

• 2 hours before the procedure you cannot eat or drink (even coffee and water)
• Before starting the measurement, it is recommended to rest for 15 minutes while sitting on the couch
• refrain from smoking for at least 4 hours
• the day before the test, do not engage in heavy physical work

The study is carried out on a clean background; before visiting the doctor, stop taking bronchodilators, because they affect airway resistance:

• 6-8 hours before short-acting drugs (berodual, salbutamol, ventolin)
• 24-36 hours before long-acting medications (Seretide, Symbicort, Foradil)

It is important to know about the state of your respiratory system; not only the quality, but also the life expectancy depends on the functioning of the lungs. The faster you exhale, the longer you will live. Spirography allows you to measure the volume and speed of exhaled air. The main purpose of spirography is to detect and confirm the diagnosis of bronchial asthma, COPD (chronic obstructive pulmonary disease), and to assess the effectiveness of prescribed medications.

Spirography determines such parameters of the respiratory system as:

• lung capacity,
• airway patency,
• breathing depth, breathing frequency,
• breathing volume,
• minute volume of breathing,
• reserve of inhalations and exhalations,
• exhalation rate,
• maximum ventilation of the lungs (ventilation limit).

The result of spirography will be a graphical recording of lung volumes (spirogram). The result of spirography can be about twenty parameters characterizing the condition of the upper respiratory tract and lungs.

Additionally, the doctor may prescribe a study with samples of bronchodilators to clarify the reversibility of pulmonary obstruction and select drug therapy. If the indicators have noticeably improved after exhaling the bronchodilator, then the process is reversible.

A correct diagnosis will help you begin timely treatment, preserving the body’s resources and the patient’s health!

Assessment of external respiratory function (ERF) is the simplest test that characterizes the functionality and reserves of the respiratory system. A research method that allows you to evaluate the function of external respiration is called spirometry. This technique has now become widespread in medicine as a valuable way to diagnose ventilation disorders, their nature, degree and level, which depend on the nature of the curve (spirogram) obtained during the study.

Assessment of external respiratory function does not allow a definitive diagnosis. However, spirometry significantly simplifies the task of making a diagnosis, differential diagnosis of various diseases, etc. Spirometry allows you to:

• identify the nature of ventilation disorders that led to certain symptoms (shortness of breath, cough);
• assess the severity of chronic obstructive pulmonary disease (COPD), bronchial asthma;
• carry out differential diagnosis between bronchial asthma and COPD using certain tests;
• monitor ventilation disorders and evaluate their dynamics, treatment effectiveness, and assess the prognosis of the disease;
• assess the risk of surgical intervention in patients with ventilation disorders;
• identify the presence of contraindications to certain physical activities in patients with ventilation disorders;
• check for the presence of ventilation disorders in patients at risk (smokers, occupational contact with dust and irritating chemicals, etc.) who are not currently complaining (screening).

The examination is carried out after half an hour of rest (for example, in bed or in a comfortable chair). The room should be well ventilated.

No complicated preparation is required for the examination. The day before spirometry, it is necessary to avoid smoking, drinking alcohol, and wearing tight clothing. You should not overeat before the test, and you should not eat less than a few hours before spirometry. It is advisable to avoid the use of short-acting bronchodilators 4-5 hours before the test. If this is not possible, the medical personnel performing the analysis must be informed of the time of the last inhalation.

During the study, tidal volumes are assessed. Instructions on how to properly perform breathing maneuvers are given by a nurse immediately before the test.

Contraindications

The technique has no clear contraindications, except for a general severe condition or impaired consciousness that does not allow spirometry to be performed. Since certain, sometimes significant efforts are required to carry out a forced respiratory maneuver, spirometry should not be performed in the first few weeks after myocardial infarction and operations on the chest and abdominal cavity, and ophthalmic surgical interventions. Determination of external respiration function should also be delayed in case of pneumothorax or pulmonary hemorrhage.

If you suspect that the person being examined has tuberculosis, you must comply with all safety standards.

Based on the results of the study, a computer program automatically creates a graph - a spirogram.

The conclusion based on the resulting spirogram may look like this:

• norm;
• obstructive disorders;
• restrictive disorders;
• mixed ventilation disorders.

What verdict the functional diagnostics doctor will make depends on whether the indicators obtained during the study correspond to normal values. Indicators of respiratory function, their normal range, values ​​of indicators according to the degree of ventilation disturbances are presented in the table^

Indicator	Norm, %	Conditionally norm, %	Mild degree of violations, %	Moderate degree of violations, %	Severe degree of violations, %
Forced vital capacity (FVC)	≥ 80	-	60-80	50-60	< 50
Forced expiratory volume in the first second (FEV1)	≥ 80	-	60-80	50-60	< 50
Modified Tiffno index (FEV1/FVC)	≥ 70 (absolute value for a given patient)	-	55-70 (absolute value for a given patient)	40-55 (absolute value for a given patient)	< 40 (абсолютная величина для данного пациента)
Average volumetric velocity of expiratory flow at the level of 25-75% of FVC (SOS25-75)	Over 80	70-80	60-70	40-60	Less than 40
Maximum volumetric flow rate at 25% of FVC (MOS25)	Over 80	70-80	60-70	40-60	Less than 40
Maximum volumetric flow rate at 50% of FVC (MOS50)	Over 80	70-80	60-70	40-60	Less than 40
Maximum volumetric flow rate at 75% of FVC (MOS75)	Over 80%	70-80	60-70	40-60	Less than 40

All data is presented as a percentage of the norm (with the exception of the modified Tiffno index, which is an absolute value, the same for all categories of citizens), determined depending on gender, age, weight and height. What is most important is the percentage compliance with standard indicators, and not their absolute values.

Despite the fact that in any study the program automatically calculates each of these indicators, the first 3 are the most informative: FVC, FEV 1 and the modified Tiffno index. Depending on the ratio of these indicators, the type of ventilation disturbance is determined.

FVC is the largest volume of air that can be inhaled after a maximum exhalation or exhaled after a maximum inspiration. FEV1 is the portion of FVC measured during the first second of a breathing maneuver.

Determining the type of violation

When only FVC decreases, restrictive disorders are determined, i.e., disorders that limit the maximum mobility of the lungs during breathing. Restrictive ventilation disorders can be caused by both pulmonary diseases (sclerotic processes in the lung parenchyma of various etiologies, atelectasis, accumulation of gas or liquid in the pleural cavities, etc.) and pathology of the chest (ankylosing spondylitis, scoliosis), leading to limitation of its mobility.

When FEV1 decreases below normal values ​​and the FEV1/FVC ratio< 70% определяют обструктивные нарушения - патологические состояния, приводящие к сужению просвета дыхательных путей (бронхиальная астма, ХОБЛ, сдавление бронха опухолью или увеличенным лимфатическим узлом, облитерирующий бронхиолит и др.).

With a joint decrease in FVC and FEV1, a mixed type of ventilation impairment is determined. The Tiffno index may correspond to normal values.

Based on the results of spirometry, it is impossible to give an unambiguous conclusion. The interpretation of the results obtained should be carried out by a specialist, always relating them to the clinical picture of the disease.

Pharmacological tests

In some cases, the clinical picture of the disease does not allow us to clearly determine whether the patient has COPD or bronchial asthma. Both of these diseases are characterized by the presence of bronchial obstruction, but narrowing of the bronchi in bronchial asthma is reversible (except for advanced cases in patients who have not received treatment for a long time), and in COPD it is only partially reversible. The reversibility test with a bronchodilator is based on this principle.

The FVD study is carried out before and after inhalation of 400 mcg of salbutamol (Salomola, Ventolin). An increase in FEV1 by 12% from the initial values ​​(about 200 ml in absolute values) indicates good reversibility of the narrowing of the lumen of the bronchial tree and is in favor of bronchial asthma. An increase of less than 12% is more typical for COPD.

Less widespread is a test with inhaled glucocorticosteroids (ICS), prescribed as trial therapy for an average of 1.5-2 months. External respiratory function is assessed before and after the administration of inhaled corticosteroids. An increase in FEV1 by 12% compared to baseline values ​​indicates the reversibility of bronchial narrowing and a greater likelihood of bronchial asthma in a patient.

When complaints characteristic of bronchial asthma are combined with normal spirometry, tests are performed to identify bronchial hyperresponsiveness (provocative tests). During them, the initial values ​​of FEV1 are determined, then inhalation of substances that provoke bronchospasm (methacholine, histamine) or an exercise test is carried out. A decrease in FEV1 by 20% from initial values ​​indicates bronchial asthma.

Key words: external respiration function, spirography, obstruction, restrictive changes, bronchial resistance

The role of the study of external respiratory function (RFF) in pulmonology is difficult to overestimate, and the only reliable criterion for chronic obstructive pulmonary diseases is respiratory disorders identified during spirometry.

Objective measurement of respiratory function as monitoring in bronchial asthma is similar to the corresponding measurements in other chronic diseases, for example, measuring blood pressure in arterial hypertension, determining glucose levels -zy for diabetes mellitus.

The main objectives of the FVD study can be formulated as follows:

1. Diagnosis of respiratory dysfunction and objective assessment of the severity of respiratory failure (RF).
2. Differential diagnosis of obstructive and restrictive pulmonary ventilation disorders.
3. Rationale for pathogenetic therapy of DN.
4. Evaluation of the effectiveness of ongoing treatment.

All indicators characterizing the state of the external respiration function can be conditionally divided into four groups.

The first group includes indicators characterizing lung volumes and capacities. Pulmonary volumes include: tidal volume, inspiratory reserve volume and residual volume (the amount of air remaining in the lungs after maximum deep exhalation). Lung capacities include: total capacity (the amount of air in the lungs after maximum inspiration), inspiratory capacity (the amount of air corresponding to the tidal volume and the inspiratory reserve volume), vital capacity of the lungs (consisting of the tidal volume, the inspiratory reserve volume -ha and exhalation), functional residual capacity (the amount of air remaining in the lungs after a quiet exhalation - residual air and expiratory reserve volume).

The second group includes indicators characterizing pulmonary ventilation: respiratory rate, tidal volume, minute respiratory volume, minute alveolar ventilation, maximum ventilation, respiratory reserve or respiratory reserve coefficient.

The third group includes indicators characterizing the state of bronchial patency: forced vital capacity (Tiffno and Votchal tests) and maximum volumetric breathing rate during inhalation and exhalation (pneumotachometry).

The fourth group includes indicators that characterize the efficiency of pulmonary respiration or gas exchange. These indicators include: the composition of alveolar air, oxygen absorption and carbon dioxide release, gas composition of arterial and venous blood.

The scope of the FVD study is determined by many factors, including the severity of the patient’s condition and the possibility (and feasibility!) of a full and comprehensive study of the FVD. The most common methods for studying FVD are spirography (Fig. 1) and spirometry.

Rice. 1. Spirogram of expiratory maneuver (according to G.E. Roytberg and A.V. Strutynsky)

Assessment of physical activity indicators

Quantitative assessment of spirographic indicators is carried out by comparing them with standards obtained from examinations of healthy people. Significant individual differences that exist among healthy people force, as a rule, to use not the general average of one or another indicator, but to take into account the gender, age, height and weight of the subjects. For most spi-ro-graphic indicators, proper values ​​have been developed; for some, the range of individual differences in healthy people has been determined. The due value in each specific case is taken as 100%, and the value obtained during the examination is expressed as a percentage of the due value.

The use of proper values ​​reduces, but does not completely eliminate, individual differences in healthy people, which for most indicators are within the range of 80-120% of the proper values, and for some - in an even wider range. Even small deviations from the results of the previous examination of the patient can indicate the magnitude and direction of the changes that have occurred. Their correct assessment can only be given taking into account the reproducibility of the indicator. It should be noted that when assessing the final result of a study, it is physiologically more justified to use the largest value rather than the average of several measurements, regardless of the number of repetitions. Below, the criteria for assessing individual spirographic readings.

Minute respiration volume (MRV)

When the patient is breathing calmly and evenly, a DO measurement is taken, which is calculated as the average value after recording at least six respiratory cycles. During the study, the patient’s usual respiratory rate (RR), depth of breathing and their qualitative relationship, the so-called breathing pattern, can be assessed. Taking into account the respiratory rate and tidal volume, the minute respiratory volume (MRV) can be calculated as the product of RR and RR.

It is well known that one of the main clinical manifestations of pulmonary insufficiency is increased and shallow breathing. However, according to instrumental research, these signs have a very limited diagnostic value.

The volume of breathing in healthy people fluctuates within a very wide range - under conditions of basal metabolism in men from 250 to 800, in women from 250 to 600, and under conditions of relative rest, respectively, from 300 to 1200 and from 250 to 800 ml, which practically deprives these indicators of diagnostic value. Thus, in chronic pneumonia, a respiratory rate of more than 24 per minute is usually observed in only 6-8% of patients, and a respiratory rate of less than 300 ml is observed in 1-3%.

Detecting hyperventilation at rest used to be of great diagnostic importance. With its presence, the idea of ​​pulmonary insufficiency was almost identified. Indeed, in patients with frequent and shallow breathing and an increase in dead space due to uneven distribution of air in the lungs, the effectiveness of ventilation deteriorates. The proportion of the respiratory volume involved in ventilation of the alveoli decreases to 1/3 versus 2/3-4/5 normally. To ensure a normal level of alveolar ventilation, it is necessary to increase the MOD, which is observed in all cases, even with hypoventilation of the alveoli.

In some pathological conditions, hyperventilation occurs as a compensatory reaction in response to disturbances in other parts of the respiratory system. Consequently, the idea of ​​hyperventilation at rest as a valuable diagnostic indicator is fair, provided that the influence of the emotional factor on ventilation is excluded. This can be achieved only with strict adherence to the conditions of the basal exchange. The conditions of relative peace do not provide any guarantees in this regard.

With relative rest, patients exhibit a tendency toward a greater increase in MOD than healthy people. So, in chronic pneumonia, an MVR of more than 200% is observed in 35-40% of cases, while in healthy people - in 15-25%, an MVR is below normal, but not less than 90% is observed extremely rarely - in only 2-5% of all cases. teas This proves the low value of this indicator.

Vital vital capacity test, FVC (forced vital capacity)

This most valuable stage in the study of the function of external respiration is the measurement of flows and volumes when performing forced ventilation maneuvers. Performing the test may provoke a coughing attack, and in some patients, even an attack of labored breathing.

The vital capacity of the lungs in healthy people ranges from 2.5 to 7.5 liters; such a spread in values ​​requires the mandatory use of the proper values. Of the many proposed formulas for calculating the proper vital capacity, the following can be recommended:

• proper vital capacity BTPS = proper basal metabolic rate * 3.0 (for men);
• proper vital capacity BTPS = proper basal metabolic rate * 2.6 (for women).

The normal limits are in the range of 80-120% of the normal value. In patients with initial pathology, vital capacity below normal is recorded in 25% of cases. In the second stage of chronic pneumonia, this figure almost doubles and amounts to 45-65%. Thus, vital capacity has a high diagnostic value.

The inspiratory reserve volume is normally 50 (35-65)% VC when sitting, and 65 (50-80)% VC when lying down. Expiratory reserve volume - sitting 30 (10-50)%, lying - 15 (5-25)% vital capacity. With pathology, there is usually a decrease in the indicators of ROvd, ROvd in % vital capacity.

Forced vital capacity in healthy people actually reproduces vital capacity and, thus, is its repetition. The differences between VC and FVC in men are 200 (-600:::+300) ml, in women - 130 (-600:::+300) ml. If FVC is greater than VC, which, although not often, can be observed both normally and in pathology, according to general rules it should be taken into account as the largest value of VC. Values ​​that go beyond the reproducibility limit of VC acquire diagnostic significance. In the case of obstruction, FVC is significantly lower than VC, and in the presence of restriction, VC will first decrease.

Maximum voluntary ventilation (MVV)

This is the most stressful part of the spirographic study. This indicator characterizes the limiting capabilities of the respiratory apparatus, depending both on the mechanical properties of the lungs and on the ability to perform the test well in connection with the general physical fitness of the subject.

In a number of patients, especially in the presence of vegetative dystonia, the performance of this maneuver is accompanied by dizziness, blurry vision, and sometimes fainting, and in patients with severe bronchial syndrome Due to obstruction, a significant increase in expiratory dyspnea is possible, so the test should be considered as potentially dangerous for the patient. At the same time, the information content of the method is low.

The air velocity indicator (APSV) is the ratio MVL/ZEL. PSDV is usually expressed in l/min. With its help, it is possible to differentiate restrictive ventilation disorders from bronchial obstruction. In patients with bronchial asthma, it can be reduced to 8-10, and with a restrictive process, it can be increased to 40 or more.

Forced expiratory volume (FEV), Tiffno index

This test has become the gold standard for diagnosing bronchial asthma and chronic obstructive pulmonary disease.

The use of a forced expiration test made it possible to monitor tracheobronchial patency using functional diagnostic methods. The result of forced exhalation is determined by a complex of anatomical and physiological properties of the lungs. A significant role is played by the resistance to the flow of exhaled air in the large bronchi and trachea. The determining factor is elastic and transmural pressure, which causes compression of the bronchi (Benson M.K., 1975 cited by). Normally, at least 70% of the forcefully exhaled air occurs in the first second of exhalation.

The main spirographic indicator of obstructive syndrome is a slowdown in forced expiration due to an increase in airway resistance and a decrease in FEV1 and Tiffno index. A more reliable sign of broncho-obstructive syndrome is a decrease in the Tiffno index (FEV1\VC), since the absolute value of FEV1 can decrease not only with bronchial obstruction, but also with restrictive disorders due to a proportional decrease in all pulmonary volumes. mov and capacities, including FEV1 and FVC. With normal lung function, the FEV1/FVC ratio is more than 80%.

Any values ​​below these may suggest bronchial obstruction. Spirography indicators lose their value when FEV1 values ​​are less than 1 liter. This method of studying bronchial patency does not take into account the decrease in the volume of forced expiration due to expiratory collapse of the bronchi during exhalation with effort. A significant drawback of the test is the need for a maximum inhalation preceding forced exhalation, which can temporarily prevent bronchospasm in healthy individuals (Nadel V. A., Tierney D. F., 1961 J, cited), and in a patient with bronchial asthma induce bronchoconstriction (Orehek J. et al., 1975, cited by). The method is unacceptable for the purposes of examination, since it entirely depends on the wishes of the patient. In addition, forced exhalation often causes coughing in patients, which is why patients with severe cough, regardless of their will, do not perform the test properly.

Air flow rate measurement

Already in the early stages of the development of obstructive syndrome, the calculated indicator of the average volumetric velocity decreases at the level of 25-75% of FVC. It is the most sensitive spirographic indicator, indicating an increase in airway resistance earlier than others. According to some researchers, a quantitative analysis of the expiratory part of the flow-volume loop also allows one to form an idea about the predominant narrowing of large or small bronchi (Fig. 2).

Rice. 2. Curves of inspiratory and expiratory volumetric flow rates (flow-volume loop) in a healthy person and a patient with obstructive syndrome (according to G.E. Roytberg and A.V. Strutynsky)

It is believed that obstruction of large bronchi is characterized by a decrease in the volumetric velocity of forced expiration, mainly in the initial part of the loop, and therefore indicators such as peak volumetric velocity (PVF) and maximum nal volumetric flow rate at 25% of FVC (MOV 25% or MEF25). At the same time, the volumetric air flow rate in the middle and end of exhalation (MOE 50% and MOE 75%) also decreases, but to a lesser extent than POSvyd and MOE 25%. On the contrary, with obstruction of small bronchi, a predominantly decrease in MVR of 50% is detected, while POS is normal or slightly reduced, and MVR is moderately reduced by 25%.

However, it should be emphasized that these provisions currently appear to be quite controversial and cannot be recommended for use in clinical practice. The indicators MOS 50% and MOS 25% are less dependent on force than MOS 75% and more accurately characterize the obstruction of small bronchi. At the same time, when obstruction is combined with restriction, leading to a decrease in FVC and a slight increase in end-expiratory velocity, one should be very careful in drawing a conclusion about the level of obstruction.

In any case, there is more reason to believe that the uneven decrease in volumetric air flow rate during forced exhalation reflects the degree of bronchial obstruction rather than its localization. The early stages of bronchial narrowing are accompanied by a slowdown in the expiratory air flow at the end and middle of exhalation (decrease in MVR 25%, MVR 75%, SOS 25-75% with little changed values ​​of MVR 25%, FEV1/FVC and POS), while with severe bronchial obstruction there is a relatively proportional decrease in all speed indicators, including the Tiffno index, POS and MOS25%.

Measuring the peak air flow rate during forced expiration (PEF) using a peak flow meter

Peak flowmetry is a simple and accessible method for measuring peak volumetric air flow velocity during forced expiration (PEE). PEF monitoring is an important clinical test used in the physician's office, emergency department, hospital, and home settings. This study allows us to assess the severity of the disease, the degree of daily fluctuations in pulmonary function, which will allow us to judge the hyperresponsiveness of the respiratory tract; it also helps to assess the effectiveness of therapy, identify clinically asymptomatic pulmonary ventilation disorders and take action before the situation becomes more serious.

In most cases, POSV correlates well with FEV1 and FEV1/FVC, the value of which in patients with broncho-obstructive syndrome varies during the day within a fairly wide range. Monitoring is carried out using modern portable and relatively inexpensive individual peak fluometers, which make it possible to quite accurately determine POV during forced exhalation. PEF variability is assessed using home 2-3-week PEF monitoring with measurements in the morning, immediately after waking up and before bedtime.

The lability of the bronchial tree is assessed by the difference between the minimum morning and maximum evening PEF values ​​as a percentage of the average daily PEF value; or lability index measuring only morning PEF - the minimum PEF value in the morning before taking a bronchodilator for one to two weeks as a percentage of the best in recent times (Min%Max).

A daily variation in PEF values ​​of more than 20% is a diagnostic sign of daily variability of the bronchial tree. The morning decrease in PEF is considered morning failure.The presence of even one morning failure during PEF measurement indicates diurnal variability of bronchial conductivity.

PEF may underestimate the degree and nature of bronchial obstruction. In this situation, spirography is performed with a broncholytic test.

When performing peak flowmetry, broncho-obstructive syndrome can be assumed if:

PEF increases by more than 15% 15-20 minutes after inhalation (fast-acting 2-agonist, or

PEF varies during the day by more than 20% in a patient receiving bronchial therapy (>10% in a patient not receiving them), or PEF decreases by more than 15% after 6 minutes of continuous running or other physical activity. heavy load.

With a well-controlled bronchial obstructive syndrome, in contrast to an uncontrolled one, PEF fluctuations do not exceed 20%.

Lung volume measurement

The parameters discussed above, measured using spirography, are highly informative in assessing obstructive disorders of pulmonary ventilation. Restrictive disorders can be diagnosed quite reliably if they are not combined with impaired bronchial obstruction, i.e. in the absence of mixed pulmonary ventilation disorders. Meanwhile, in a doctor’s practice, mixed disorders are most often encountered (for example, with bronchial asthma or chronic obstructive bronchitis, complicated by emphysema and pneumosclerosis). In these cases, disturbances in pulmonary ventilation can be diagnosed by analyzing the size of the lung volumes, in particular the structure of the total lung capacity (TLC or TLC).

To calculate TLC, it is necessary to determine the functional residual capacity (FRC) and calculate the indicators of residual lung volume (FRC or RV).

Obstructive syndrome, characterized by limitation of air flow in the upper extremity, is accompanied by a clear increase in TLC (more than 30%) and FRC (more than 50%). Moreover, these changes are detected already in the early stages of the development of bronchial obstruction. In case of restrictive pulmonary ventilation disorders, TEL is significantly lower than normal. At clean restriction (without combination with obstruction), the structure of the TLC does not change significantly, or a slight decrease in the ratio of TLC/TLC is observed. If restrictive disorders occur against the background of bronchial obstruction, then along with a clear decrease in TLC, a significant change in its structure is observed, characteristic of broncho-obstructive syndrome: an increase in TLC/TLC (more than 35%) and FRC/TLC ( more than 50%). With both types of restrictive disorders, vital capacity decreases significantly.

Thus, the analysis of the structure of the TEL makes it possible to differentiate all three variants of ventilation disorders (obstructive, restrictive and mixed), while the analysis of only spirographic indicators does not make it possible to reliably distinguish the mixed variant from the obstructive, accompanying one. given by a decrease in vital capacity (see table).

Table.

Airway resistance measurement

Compared to the previously described tests, airway resistance measurement is not as widely used in clinical practice. However, bronchial resistance is a diagnostically important parameter of pulmonary ventilation. Unlike other methods for studying respiratory function, measuring bronchial resistance does not require patient cooperation and can be used in children, as well as for the purpose of examination in patients of any age.

Indicators of aerodynamic resistance of the respiratory tract make it possible to differentiate true obstruction from functional disorders (for example, in the case of pro-vi-sa-niya volume-flow loops, normal resistance and OO numbers indicate a vegetative imbalance of bronchial innervation). Maximum inhalation and forced exhalation can cause narrowing of the bronchi, as a result of which sometimes when bronchodilators are prescribed, FEV1 remains the same or even decreases. In these cases, it becomes necessary to measure the resistance of the airways using whole body plethysmography (see below).

As is known, the main force ensuring the transfer of air along the airways is the pressure gradient between the oral cavity and the alveoli. The second factor that determines the amount of gas flow through the airways is the aerodynamic resistance (Raw), which in turn depends on the clearance and length of the airways, as well as on viscosity gas The volumetric velocity of air flow obeys Poiseuille’s law:

where V is the volumetric velocity of laminar air flow;

∆P-pressure gradient in the oral cavity and alveoli;

Raw aerodynamic resistance of the airways.

Consequently, to calculate the aerodynamic resistance of the airways, it is necessary to simultaneously measure the difference between the pressure in the oral cavity and al-ve-o-lah, as well as the volumetric air flow rate:

There are several methods for determining airway resistance, including

• whole body plethysmography method;

• method of blocking the air flow.

Whole body plethysmography method

During plethysmography, the subject sits in a sealed chamber and through a breathing tube breathes air coming from the extra-chamber space. The breathing tube begins with a mouthpiece and has a stopper that allows you to block the flow of respiratory gases. Between the mouthpiece and the flap there is a pressure sensor for the gas mixture in the oral cavity. Distal to the damper in the breathing tube there is a gas mixture flow sensor (pneumotachometer).

To determine the resistance of the airways, two maneuvers are performed: first, the subject breathes through an open hose connected to a pneumotachograph, and the individual relationship between the volumetric velocity of the air flow (V) and the changing pressure in the plethysmograph chamber (Pcam) is determined. . This dependence is registered in the form of a so-called bronchial resistance loop. In this case:

The inclination of the bronchial resistance loop to the PKam axis (tgα) is inversely proportional to the value of Raw, i.e. the smaller the angle α, the smaller the air flow and the greater the resistance of the airways.

To calculate specific Raw values, it is necessary to establish a relationship between Ralv and Rkam. With the hose valve closed, the patient makes short attempts inhalation And exhalation. Under these conditions, alveolar pressure is equal to the pressure in the oral cavity. This allows you to register a second dependency between Ralv (or Prot) and Rkam:

Thus, as a result of performing two breathing maneuvers, the value of air flow velocity V and alveolar pressure Ralv, necessary for calculation, can be expressed through the pressure in the plethysmograph chamber Rkam. Substituting these values ​​into the formula for determining Raw we get:

Airflow shutoff method

This method is used more often because it makes it easier to determine bronchial resistance. The technique is based on the same principles as determination using integral plethysmography.

The magnitude of the air flow velocity is measured during quiet breathing through a pneumotachographic tube. To determine Ralv, a short-term (no more than 0.1 s) shutdown of the air flow is automatically performed using an electromagnetic damper. In this short period of time, Ralf becomes equal to the pressure in the oral cavity (PP). Knowing the value of the air flow velocity (V) immediately before the moment of closure of the pneumotachographic tube and the value of Ralf, it is possible to calculate the resistance of the airways:

Normal values ​​of tracheobronchial resistance (Raw) are 2.5-3.0 cmH2O. st/l/s.

It should be noted that the method of blocking the air flow allows you to obtain accurate results provided that the pressure in the system is equalized very quickly (within 0.1 s) alveoli-bronchi-trachea-oral cavity. Therefore, in cases of severe impairment of bronchial patency, when there is significant unevenness of pulmonary ventilation, the method gives underestimated results.

When using the technique of interrupting the air flow with a valve to determine the alveolar pressure, its value is influenced by the asynphase resistance of the lungs, which leads to a false increase in alveolar pressure and, consequently, to a false increase in bronchial resistance .

In order to take into account the differences in indicators obtained by different methods, the value of airway resistance measured in a body plethysmograph has traditionally been called bronchial resistance. And the value measured by the dynamic component of transpulmonary pressure is aerodynamic resistance. In principle, these concepts are synonymous; the only difference is that different methods are used to measure them.

In clinical practice, the reciprocal of Raw is often used (1/ Raw airway conductivity). When analyzing the results of plethysmography, the concept is also used specific conductivity of the airways-Gaw:

where VGO is the intrathoracic volume of gas.

Normal Gaw values ​​are around 0.25 water column.

An increase in Raw and a decrease in Gaw indicate the presence of an obstructive syndrome. The upper respiratory tract accounts for about 25%, the trachea, lobar, segmental bronchi account for about 60%, and the small airways account for about 15% of the total airway resistance.

An increase in airway resistance may be due to:

1. swelling of the mucous membrane and hypersecretion of mucus (for example, with bronchitis);
2. spasm of smooth muscles (bronchial asthma);
3. narrowing of the larynx caused by inflammatory or allergic edema or tumor of the larynx;
4. the presence of a tracheal tumor or dyskinesia of the membranous part of the tracheal mucosa;
5. bronchogenic lung cancer, etc.

It should be noted that the interpretation of the results of the FVD study should be made taking into account the clinical picture and other paraclinical studies.

Literature

1. Bodrova T.N., Tetenev F.F., Ageeva T.S., Levchenko A.V., Larchenko V.V., Danilenko V.Yu., Kashuta A.Yu. The structure of inelastic resistance of the lungs during community-acquired pneumonia. Bull. Siberian medicine. 2006, N3.
2. Grippi M.A. Pathophysiology of the respiratory organs (translated from English) M.: Binom, 1998, p. 61-79.
3. Nobel J. Classics of modern medicine, general medical practice, vol. 3 (translated from English) M.: Praktika, 2005, 504, p. 661-671.
4. Drannik G.N. Clinical immunology and allergology. Kyiv: Polygraph Plus, 2006, p. 361-367.
5. Lawlor G., Fisher T., Adelman D. Clinical immunology and allergology, M.: Prak-ti-ka, 2000, 173-190.
6. Novik G.A., Borisov A.V. Spirometry and peak flowmetry for bronchial asthma in children. Textbook / ed. Vorontsova. SPb.: Publishing house. GPMA, 2005, p. 5-46.
7. Roytberg G.E., Strutynsky A.V. Internal diseases. Respiratory system. M.: Bi-nom, 2005, p. 56-74.
8. Silvestrova V.P., Nikitina A.V. Non-specific lung diseases: clinical picture, diagnosis, treatment. Voronezh. ed. VSU, 1991, 216 p.
9. Tetenev F.F. Obstructive theory of external respiration disorders. Status, development prospects. Bull. Siberian Medicine, 2005, N4. With. 13-27.
10. Chuchalin A.G. Bronchial asthma. M.: Publishing house. house Russian doctor, 2001, 144 p.
11. Chuchalin A.G. Standards for the diagnosis and treatment of patients with chronic diseases. obstr. lung disease ATS\ERS, revision 2004. (translated from English). M., 2005, 95 p.
12. Chuchalin A.G. Chronic obstructive pulmonary diseases. M.: Binom, St. Petersburg, 1998, p. 18.
13. Ajanovic E., Ajanovic M., Prnjavorac B. Possibilities of diagnosis of bronchial obstruction, Pluncne Bolesti, 1991 Jan-Jun; 43(1-2):35-9.
14. American Thoracic Society: Lung function testing: selection of reference values ​​and interpretative strategies, Am. Rev Respira. Dis., 1991, 144; p. 1202.
15. American Thoracic Society. National Heart, Lung, and Blood Institute. European Respiratory Society. Consensus statement on measurements of lung volumes in humans, 2003.
16. American Thoracic Society. Standards for the diagnosis and care with chronic obstructive pulmonary disease, Am. Rev. Respira. Dis., 1995; 152, 77-120.
17. Ane Johannessen, Sverre Lehmann, Ernst Omenaas, Geir Egil Eide, Per Bakke, and Amund Gulsvik.Defining the Lower Limit of Normal for FEV1/ FVC, Am. J. Respira. Crit. Care Med., 176: 101a-102a.
18. Banovcin P., Seidenberg J., Von der Hardt H. Assessment of tidal breathing patterns for monitoring of bronchial obstruction in infants, Pediatr. Res., 1995 Aug; 38(2): 218-20.
19. Benoist M.R., Brouard J.J., Rufin P., Delacourt C., Waernessyckle S., Scheinmann P. Ability of new lung function tests to assess metacholine-induced airway obstruction in infants, Pediatric Pulmonol., 1994 Nov;18(5):308 -16.
20. Bernd Lamprecht, Lea Schirnhofer, Falko Tiefenbacher, Bernhard Kaiser, Sonia A. Buist, Michael Studnicka, and Paul Enright Six-Se-cond Spirometry for Detection of Airway Obs-truction: A Population-based Study in Austria, Am. J. Respira. Crit. Care Med., 176: 460–464.
21. Blonshine S.B. Pediatric pulmonary function testing, Respir. Care Clin. N. Am., 2000 Mar; 6(1): 27-40.
22. Carpo RO. Pulmonary-function testing, N. Engl. J Med 1994;331:25-30.
23. D"Angelo E., Prandi E., Marazzini L., and Milic-Emili J. Dependence of maximal flow-volume curves on the time course of preceding inspiration in patients with chronic obstruction pulmonary disease, Am. J. Respir. Crit. Care Med., 150: 1581-1586.
24. Feyrouz Al-Ashkar, Reena Mehza, Peter J Maz-zone Interpreting pulmonary function tests: Recognize the pattern, and the diagnosis will follow, Clevland Clinic Journal of Medicine, 10, Oct 2003, 866-881.
25. Gold W.M. Pulmonary function testing. In: Murray J.F., Nadel J.A., Mason R.J., Boushey H.A., eds. Textbook of Respiratory Medicine. 3rd edition. Philadelphia: W.B. Sauders, 2000: 781-881.
26. Gross V., Reinke C., Dette F., Koch R., Vasilescu D., Penzel T., Koehler U. Mobile nocturnal long-term monitoring of wheezing and cough, Biomed. Tech. (Berl), 2007; 52(1):73-6.
27. Hyatt R.E., Scanlon P.D., NakamuraM. An approach to interpreting pulmonary function tests.In: Hyatt R.E., Scanlon P.D., Nakamura M. Interpretation of Pulmonary Function Tests: A Practical Guide.Philadelfia: Lippincott-Raven, 1997:121-131.
28. Hyatt R.E., Scanlon P.D., Nakamura M. Diffusing capacity of the lungs.Interpretation of pulmonary Function Tests: A Practical Guide. Philadelfria: Lippicott-Raven, 1997:5-25.
29. James E. Hansen, Xing-Guo Sun, and Karlman Wasserman Ethnic- and Sex-free Formula for Detection of Airway Obstruction, Am. J. Respira. Crit. Care Med., 174: 493–498.
30. Klein G., Urbanek R., Kohler D., Matthys H. Inhalation bronchial provocation tests in chil-dren: comparative measurements of oscillation, occlu- sion pressure and plethysmographic resis-tan-ce, Clin. Pediatr., 1983 Jan-Feb; 195(1):33-7.
31. Loland L., Buchvald F.F., Halkjaer L.B., Anhshj J., Hall G.L., Persson T., Krause T.G., Bisgaard H. Sensitivity of bronchial responsiveness measures in young infants, Chest, 2006 Mar;129(3): 669- 75.
32. Macklem P. Respiratory mechanics, Ann. Rev. Physiol. Palo. Alto. Calif., 1978, 40, p. 157-184.
33. Marchal F., Schweitzer C., Thuy L.V. Forced oscillations, interrupter technique and body plethysmography in the preschool child, Pediatr. Respira. Rev., 2005 Dec; 6(4):278-84, Epub 2005 Nov 8..
34. McKenzie S., Chan E., Dundas I. Airvay resis-tan-ce measured by the interrupter techniqe: nor-ma-tive data for 2-10 year olds of three ethnicities, Arch. Dis. Child., 2002 Sep; 87(3):248-51.
35. National Heart, Lung, and Blood Institute. Highlights of the Expert Panel Report 2: Guidelines for the diagnosis and management of asthma: Bethesda, Md: Department of Health and Human Services, NIH publication N 97-4051 A, 1997.
36. Paul L. Enright, Kenneth C. Beck, and Duane L. Sherrill Repeatability of Spirometry in 18,000 Adult Patients, Am. J. Respira. Crit. Care Med., 169: 235-238.
37. Wise R. A., Connett J., Kurnow K., Grill J., Johnson L., Kanner R., and Enright P. Selection of spirometric measurements in a clinical trial, the Lung Health Study, Am. J. Respira. Crit. Care Med., 151: 675-681.
38. Santolicandro A., Fornai E., Pulera N., Giuntini C. Functional aspects of reversible airway obs-truction, Respiration, 1986; 50 Suppl. 2:65-71.
39. Timothy B. Op"t Holt. Understanding the Essen-ti-als Waveform Analysis, AARC Times, 1999, 7-12.
40. Wanger J. Appendix 4: Selected adult reference populations, methods, and regression equations for spirometry and lung volumes. In: Wanger J. Pulmonary Function Testing: A Practical Ap-proach.2 nd edition. Baltimore: Willams & Wilkins, 1996: 227-281.
41. Wanger J. Forced spirometry, In: Wanger J. Pul-mo--nary Function testing: A Practical Approach. 2nd edition. Baltimore: Wiliams & Wilkins, 1996:1-76.
42. Zapletal A., Chalupova J. Forced expiratory pa-ra-meters in healthy preschool children (3-6 years of age), Pediatr. Pulmonol., 2003 Mar; 35(3):200-7.