Vital capacity of the lungs - norms and causes of deviations. Proper vital capacity (JL)

During inhalation, the lungs are filled with a certain amount of air. This value is not constant and can change under different circumstances. The volume of the lungs of an adult depends on external and internal factors.

What affects lung capacity

The level of filling the lungs with air is influenced by certain circumstances. In men, the average organ volume is larger than in women. In tall people with a large body constitution, the lungs can hold more air on inspiration than in short and thin people. With age, the amount of inhaled air decreases, which is a physiological norm.

Regular smoking reduces lung capacity. Low fullness is characteristic of hypersthenics (short people with a rounded body, shortened broad-boned limbs). Asthenics (narrow-shouldered, thin) are able to inhale more oxygen.

All people living high relative to sea level (mountainous areas) have reduced lung capacity. This is due to the fact that they breathe rarefied air with low density.

Temporary changes in the respiratory system occur in pregnant women. The volume of each lung is reduced by 5-10%. The rapidly growing uterus increases in size, presses on the diaphragm. This does not affect the general condition of the woman, since compensatory mechanisms are activated. Due to accelerated ventilation, they prevent the development of hypoxia.

Average lung volume

The volume of the lungs is measured in liters. Average values are calculated during normal breathing at rest, without deep breaths and full exhalations.

On average, the indicator is 3-4 liters. In physically developed men, the volume with moderate breathing can reach up to 6 liters. The number of respiratory acts is normally 16-20. With active physical exertion, nervous strain, these figures increase.

ZHOL, or vital capacity of the lungs

VC is the maximum capacity of the lung during maximum inhalation and exhalation. In young, healthy men, the indicator is 3500-4800 cm 3, in women - 3000-3500 cm 3. For athletes, these figures increase by 30% and amount to 4000-5000 cm 3. Swimmers have the largest lungs - up to 6200 cm 3.

Considering the phases of ventilation of the lungs, the following types of volume are divided:

respiratory - air freely circulating through the bronchopulmonary system at rest;
reserve on inspiration - air filled by the organ during maximum inspiration after a calm exhalation;
reserve on exhalation - the amount of air removed from the lungs during a sharp exhalation after a calm breath;
residual - the air remaining in the chest after maximum exhalation.

Airway ventilation refers to gas exchange for 1 minute.

The formula for its definition:

tidal volume × number of breaths/minute = minute volume of breath.

Normally, in an adult, ventilation is 6-8 l / min.

Table of indicators of the norm of the average lung volume:

The air that is in such parts of the respiratory tract does not participate in gas exchange - the nasal passages, nasopharynx, larynx, trachea, central bronchi. They constantly contain a gas mixture called "dead space", and is 150-200 cm 3.

VC measurement method

External respiratory function is examined using a special test - spirometry (spirography). The method fixes not only the capacity, but also the speed of circulation of the air flow.
For diagnosis, digital spirometers are used, which have replaced mechanical ones. The device consists of two devices. A sensor for fixing the air flow and an electronic device that converts measurements into a digital formula.

Spirometry is prescribed for patients with impaired respiratory function, broncho-pulmonary diseases of a chronic form. Evaluate calm and forced breathing, conduct functional tests with bronchodilators.

Digital data on VC during spirography are distinguished by age, gender, anthropometric data, the absence or presence of chronic diseases.

Formulas for calculating individual VC, where P is height, B is weight:

for men - 5.2 × P - 0.029 × B - 3.2;
for women - 4.9 × P - 0.019 × B - 3.76;
for boys from 4 to 17 years old with growth up to 165 cm - 4.53 × R - 3.9; with growth over 165 cm - 10 × R - 12.85;
for girls from 4 to 17 years old, swarms grow from 100 to 175 cm - 3.75 × R - 3.15.

Measurement of VC is not carried out for children under 4 years of age, patients with mental disorders, with maxillofacial injuries. Absolute contraindication - acute contagious infection.

Diagnostics is not prescribed if it is physically impossible to conduct a test:

neuromuscular disease with rapid fatigue of the striated muscles of the face (myasthenia gravis);
postoperative period in maxillofacial surgery;
paresis, paralysis of the respiratory muscles;
severe pulmonary and heart failure.

Reasons for an increase or decrease in VC

Increased lung capacity is not a pathology. Individual values depend on the physical development of a person. In athletes, the YCL can exceed the standard values by 30%.

Respiratory function is considered impaired if the volume of a person's lungs is less than 80%. This is the first signal of insufficiency of the bronchopulmonary system.

External signs of pathology:

respiratory failure during active movements;

change in the amplitude of the chest.

Initially, it is difficult to determine violations, since compensatory mechanisms redistribute air in the structure of the total volume of the lungs. Therefore, spirometry is not always of diagnostic value, for example, in pulmonary emphysema, bronchial asthma. In the course of the disease, swelling of the lungs is formed. Therefore, for diagnostic purposes, percussion is performed (low position of the diaphragm, a specific “box” sound), chest x-ray (more transparent fields of the lungs, expansion of boundaries).

Decreasing factors for VC:

a decrease in the volume of the pleural cavity due to the development of a pulmonary heart;
rigidity of the parenchyma of the organ (hardening, limited mobility);
high standing of the diaphragm with ascites (accumulation of fluid in the abdominal cavity), obesity;
pleural hydrothorax (effusion in the pleural cavity), pneumothorax (air in the pleural sheets);
diseases of the pleura - tissue adhesions, mesothelioma (tumor of the inner lining);
kyphoscoliosis - curvature of the spine;
severe pathology of the respiratory system - sarcoidosis, fibrosis, pneumosclerosis, alveolitis;
after resection (removal of part of the organ).

Systematic monitoring of VC helps to track the dynamics of pathological changes, take timely measures to prevent the development of diseases of the respiratory system.

Each respiratory movement at rest is accompanied by the exchange of a relatively small volume of air - 500 ml. This volume of air is called respiratory. After completing a quiet breath, a person can take another breath, and another 1500 ml will enter the lungs - this is the so-called additional volume.

Similarly, after a simple exhalation, with effort, a person can exhale an additional 1500 ml of air, which is called a reserve exhalation.

Vital capacity, spirometer

The total volume of the described quantities - breathing air, additional and reserve - in total equals an average of 3500 ml. The vital capacity of the lungs is the volume of air exhaled after a forced inhalation and a deep exhalation. It can be measured with a spirometer - a special device. 3000-5000 ml.

A spirometer is a device that helps to measure capacity and evaluate taking into account the volume of forced exhalation after a deep breath. This device is best used in a sitting position, placing the device itself vertically.

Vital capacity, as determined by a spirometer, is an indicator of restrictive diseases (eg,

The device allows these diseases to be distinguished from disorders that cause blockage of the airways (asthma, for example). The importance of this diagnosis is great, since the degree of development of diseases of this type is difficult to determine on the basis of clinical symptoms.

Breathing process

With calm breathing (inhalation), out of 500 ml of inhaled air, no more than 360 ml reaches the pulmonary alveoli, while the rest is retained in the airways. Under the influence of work in the body, oxidative processes are intensified, and the amount of air is insufficient, i.e., the need for oxygen consumption and the release of carbon dioxide increases. The vital capacity of the lungs must be increased under these conditions. The body for normal pulmonary ventilation must increase the frequency of breathing and the volume of inhaled air. With a sharp increase in breathing, it becomes superficial, and only a small part of the air reaches the pulmonary alveoli. Deep breathing improves lung ventilation and proper gas exchange occurs.

Prevention of lung diseases

Sufficient vital capacity of the lungs is a very important factor that contributes to maintaining the health and good performance of a person. Properly developed, to a certain extent, ensures normal breathing, so morning exercises, sports, and physical education are very important. They contribute to the harmonious physical development of the body and chest as well.

The vital capacity of the lungs depends on the purity of the surrounding air. Fresh air has a positive effect on the body. On the contrary, the air in stuffy enclosed spaces, saturated with water vapor and carbon dioxide, has a negative effect on the breathing process. The same can be said about smoking, inhaling dust and polluted particles.

Improvement measures include planting greenery in cities and residential areas, asphalting and watering streets, installing smoke detectors at enterprises, and absorbing ventilation devices in houses.

In modern medicine, in patients of various ages with symptoms of respiratory diseases, one of the main diagnostic methods is the method of studying the function of external respiration (RF). This research method is the most accessible and allows assessing the ventilation functionality of the lungs, i.e. their ability to provide the human body with the necessary amount of oxygen from the air and remove carbon dioxide.

Vital capacity of the lungs

For a quantitative description, the total lung capacity is divided into several components (volumes), i.e. lung capacity is a collection of two or more volumes. Lung volumes are divided into static and dynamic. Static are measured during completed respiratory movements without limiting their speed. Dynamic volumes are measured when performing respiratory movements with a temporary restriction on their implementation.

Vital capacity (VC) includes: tidal volume, expiratory reserve volume, and inspiratory reserve volume. Depending on gender (male or female), age and lifestyle (sports, bad habits), the norm varies from 3 to 5 (or more) liters.

Depending on the method of determination, there is:

Inhalation VC - at the end of a full exhalation, a maximum deep breath is taken.
Expiratory VC - at the end of inhalation, maximum exhalation is carried out.

Tidal volume (TO, TV) - the volume of air inhaled and exhaled by a person during quiet breathing. The value of the tidal volume depends on the conditions under which measurements are performed (at rest, after exercise, body position), sex and age. The average is 500 ml. It is calculated as an average after measuring six even, normal for a given person, respiratory movements.

Inspiratory reserve volume (IRV, IRV) is the maximum amount of air that can be inhaled by a person after his usual breath. The average value is from 1.5 to 1.8 liters.

Expiratory reserve volume (ERV) is the maximum volume of air that can be exhaled additionally by making your normal exhalation. The size of this indicator is smaller in a horizontal position than in a vertical one. Also, expiratory RO decreases with obesity. On average, it is from 1 to 1.4 liters.

What is spirometry - indications and diagnostic procedure

Examination of the function of external respiration

Determination of indicators of static and dynamic lung volumes is possible when conducting a study of the function of external respiration.

Static lung volumes: tidal volume (TO, TV); expiratory reserve volume (RO vyd, ERV); inspiratory reserve volume (RO vd, IRV); vital capacity of the lungs (VC, VC); residual volume (C, RV), total lung capacity (TLC, TLC); airway volume ("dead space", MT on average 150 ml); functional residual capacity (FRC, FRC).

Dynamic lung volumes: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), Tiffno index (FEV1 / FVC ratio, expressed as a percentage), maximum lung ventilation (MVL). The indicators are expressed as a percentage of the values determined individually for each patient, taking into account his anthropometric data.

The most common method for studying the respiratory function is considered to be the method, which is based on the recording of the flow-volume curve during the implementation of enhanced exhalation of the vital capacity of the lungs (FVC). The capabilities of modern instruments make it possible to compare several curves; on the basis of this comparison, it is possible to determine the correctness of the study. The correspondence of the curves or their close location indicates the correct performance of the study and well-reproducible indicators. When performing enhanced exhalation is done from the position of maximum inspiration. In children, unlike the study technique in adults, the expiration time is not set. Forced exhalation is a functional load on the respiratory system, therefore, between attempts, you should take breaks of at least 3 minutes. But even under these conditions, there may be obstruction from spirometry, a phenomenon in which, with each subsequent attempt, there is a decrease in the area under the curve and a decrease in the recorded indicators.

The unit of measurement of the obtained indicators is a percentage of the due value. Evaluation of the data of the flow-volume curve makes it possible to find possible violations of bronchial conduction, assess the severity and extent of the detected changes, determine at what level changes in the bronchi or violations of their patency are noted. This method allows to detect lesions of small or large bronchi or their joint (generalized) disorders. Diagnosis of patency disorders is performed based on the assessment of FVC and FEV1 and indicators characterizing the speed of air flow through the bronchi (maximum high-speed flows in areas of 25.50 and 75% FVC, peak expiratory flow).

Difficulties during the examination are presented by the age group - children aged 1 to 4 years, due to the peculiarities of the technical part of the study - the performance of respiratory maneuvers. Based on this fact, the assessment of the functioning of the respiratory system in this category of patients is based on an analysis of clinical manifestations, complaints and symptoms, an assessment of the results of the analysis of the gas composition and CBS, arterialized blood. In connection with the presence of these difficulties, in recent years, methods based on the study of calm breathing have been developed and are actively used: bronchophonography, pulse oscillometry. These methods are mainly intended for the assessment and diagnosis of the patency of the bronchial tree.

Test with a bronchodilator

When deciding whether to make a diagnosis of "bronchial asthma" or clarify the severity of the condition, a test (test) with a bronchodilator is performed. For carrying out, short-acting β2 agonists (Ventolin, Salbutamol) or anticholinergic drugs (Ipratropium bromide, Atrovent) are usually used in age dosages.

If the test is planned for a patient who receives bronchodilators as part of the basic therapy, for proper preparation for the study, they should be canceled before the start of the study. Short-acting B2-agonists, anticholinergic drugs are canceled within 6 hours; long-acting β2-agonists are canceled per day. If the patient is hospitalized for emergency reasons and bronchodilators have already been used at the stage of pre-hospital care, the protocol must indicate which drug was used in the study. Carrying out a test while taking these drugs can "deceive" a specialist and lead to an incorrect interpretation of the results. Before conducting a test with a bronchodilator for the first time, it is necessary to clarify the presence of contraindications to the use of these groups of drugs in a patient.

The algorithm for conducting a sample (test) with a bronchodilator:

a study of the function of external respiration is performed;
inhalation with a bronchodilator is carried out;
re-examination of the function of external respiration (the dosage and time interval after inhalation to measure the bronchodilatory response depend on the selected drug).

At the moment, there are different approaches to the methodology for evaluating the results of a test with a bronchodilator. The most widely used assessment of the result is an unconditional increase in the FEV1 indicator. This is explained by the fact that when studying the characteristics of the flow-volume curve, this indicator turned out to have the best reproducibility. An increase in FEV1 by more than 15% of the initial values is conditionally characterized as the presence of reversible obstruction. Normalization of FEV1 in the test with bronchodilators in patients with chronic obstructive pulmonary disease (COPD) occurs in rare cases. A negative result in the test with a bronchodilator (an increase of less than 15%) does not negate the possibility of an increase in FEV1 by a large amount during long-term adequate drug therapy. After a single test with β2-agonists, a third of patients with COPD showed a significant increase in FEV1, in other groups of patients this phenomenon can be observed after several tests.

Peakflowmetry

This is the measurement of peak expiratory flow (PEF, PEF) using portable devices at home in order to monitor the patient's condition with bronchial asthma.

For the study, the patient needs to inhale the maximum possible volume of air. Next, the maximum possible exhalation into the mouthpiece of the device is performed. Usually three measurements are taken in a row. For registration, the measurement with the best result of the three is selected.

The limits of the norm of peak flowmetry indicators depend on the sex, height and age of the subject. Recording of indicators is carried out in the form of a diary (graph or table) of peak flow measurements. Twice a day (morning/evening), the scores are recorded in the diary as a point corresponding to the best of the three attempts. Then these points are connected by straight lines. Under the graph, a special field (column) for notes should be allocated. They indicate the medications taken over the past day, and factors that could affect the person's condition: weather changes, stress, the addition of a viral infection, contact with a large amount of a causally significant allergen. Regular filling in the diary will help to identify in a timely manner what caused the deterioration in well-being and evaluate the effect of drugs.

Bronchial patency has its own daily fluctuations. In healthy people, fluctuations in PSV should not be more than 15% of the norm. In people with asthma, fluctuations during the day during the period of remission should not be more than 20%.

The system of zones on the peak flow meter is based on the principle of a traffic light: green, yellow, red:

Green zone - if the PSV values are within this zone, they talk about clinical or pharmacological (if the patient uses drugs) remission. In this case, the patient continues the drug therapy regimen prescribed by the doctor and leads his usual lifestyle.
The yellow zone is a warning about the beginning of a possible deterioration in the condition. When lowering PSV values within the boundaries of the yellow zone, it is necessary to analyze the diary data and consult a doctor. The main task in this situation is to return the indicators to the values in the green zone.
The red zone is a danger signal. You need to contact your doctor immediately. There may be a need for urgent action.

Adequate control over the condition allows you to gradually reduce the amount of drug therapy used, leaving only the most necessary drugs in minimal dosages. The use of a traffic light system will allow timely detection of health-threatening disorders and help prevent unplanned hospitalization.

Balakina Victoria., Eliseeva Olga., Mendel Anna., Reshetova Elena., Sergeeva Anastasia., Kiryukhin Egor.

Man is naturally inquisitive. He is interested in everything that concerns the structure and life of his own organism. Breathing takes a special place. We feel breathing more than any other physiological function. We can observe our breathing, we can control it. From what and how we breathe, to a large extent depends on our performance, health and, ultimately, life. Vital capacity (VC) is the maximum expiratory volume after a maximum inhalation. VC is not the same in different people and varies in them within very significant limits, but in the same individual it can be very close during the active period. VC is greatly influenced by gender, age, height, climate, altitude, as well as health status and sports. VC due to the development of the chest and lungs increases up to 18 years. From the age of 18 to 32, it remains at the same level, and then begins to gradually decrease. Women have less vital capacity than men.

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The study of changes in the vital capacity of the lungs from various factors GBOU secondary school No. 1024 8 "A" class

Hypothesis: Changes in lung capacity are determined by the characteristics of muscle activity and depend on age, gender, sports and smoking. Object of study: The vital capacity of the lungs of students of the 8th "A" class. Subject of study: Changes in lung capacity. Purpose of the study: To study changes in the vital capacity of the lungs of students depending on sports, smoking, age and gender. Objectives of the study: 1. To study the features of changes in the vital capacity of the lungs, depending on the practice of various sports. 2. To study the dynamics of lung vital capacity. 3. Identify factors that determine the change in lung capacity.

Respiration is a set of processes that ensure the continuous supply of all organs and tissues of the body with oxygen and the removal from the body of carbon dioxide constantly formed in the process of metabolism.

Respiratory tract Respiratory tract: Upper: Nasal cavity Nasopharynx Oropharynx Lower: Larynx Trachea Bronchi

The lungs occupy all the free space in the chest cavity. Each lung is covered with a membrane - the pulmonary pleura. The chest cavity is also lined with a membrane - the parietal pleura. Between the parietal and pulmonary pleura, a narrow gap is the pleural cavity, which is filled with the thinnest layer of fluid, which facilitates the sliding of the lung wall during inhalation and exhalation.

The human lungs are made up of tiny pulmonary sacs called alveoli. The alveoli are densely braided with a network of blood vessels - capillaries. The epithelium secretes a special fluid lining the alveoli. Its functions: prevents the alveoli from closing and kills microbes that have entered the lungs. In the alveoli, gas exchange takes place between the blood and the surrounding air by diffusion.

The exchange of gases between atmospheric air and the air in the alveoli occurs due to the rhythmic alternation of inhalation and exhalation. In the implementation of inhalation and exhalation, the intercostal muscles, the diaphragm, as well as a number of auxiliary respiratory muscles take part: scalene, pectoral, trapezius and abdominal muscles.

Vital lung capacity (VC) VC is one of the main indicators of the state of the external respiration apparatus, widely used in medicine. The vital capacity of the lungs is the maximum amount of air exhaled after the deepest breath.

Research methods: Method for determining growth Method for determining VC using a balloon Calculation methods for determining VC

At the first stage, the volume of the lungs is measured using a balloon. To obtain greater measurement accuracy, it is desirable to use a balloon that, when inflated, has a shape close to a sphere.

At the second stage, the growth of all members of the group was measured using a stadiometer.

The third stage included checking the reliability of the obtained experimental data with the average calculated values for height and age. To assess the individual value of VC in practice, it is customary to compare it with the so-called due VC (JEL), which is calculated according to various empirical formulas

The results of the measurement of VC among classmates

Tabular values of lung volume All students have indicators above the average lung volume norm.

Comparison of the vital capacity of light classmates with the calculated

The results of measuring VC among classmates by sex Average result of girls: 2750 Average result of boys: 3400

Comparison of indicators of students with different physical fitness

Recommendations for sports: Korovkina A, Sergeeva A., Eliseeva O., Perevozova Yu., Tverezaya E., Reshetova E. Gymnastics recommended Orlov A., Saprygin A., Mukhkhamad H. Football recommended Kiryukhin E., Pakhlyan S ., Pronina S. Recommended for cycling Zabotin N., Lopatina A. Recommended for athletics Shcherbakov V., Mendel A. Recommended for swimming

If we compare the lungs of a smoker and a healthy person, we will immediately notice the difference. Pulmonary partitions made of connective tissue absorb the smallest particles of soot. Such a plaque occurs literally from the first cigarette smoked. Soot and dust particles clog the lumen of the bronchi and bronchioles, narrowing them, which leads to shortness of breath during physical exertion and a sharp decrease in lung capacity by 950 ml.

Conclusions: 1. The vital capacity of the lungs is one of the main indicators of the state of the respiratory system. 2. The value of VC normally depends on the sex, age of the person, his physique, the degree of development of the chest and respiratory muscles. 3. With various diseases, it can change significantly, which reduces the ability of the patient's body to adapt to physical activity. 4. A significant factor that reduces VC is SMOKING! 5. A person involved in sports has a large vital capacity of the lungs. 6. Recommendations were given to the group members on the choice of a sport.

Thank you for your attention!

VITAL CAPACITY (VC)- the maximum amount of air exhaled after a maximum deep breath. VC is one of the indicators of external respiration (see) and is a combination of three lung volumes (Fig.) - tidal volume (volume of inhaled or exhaled air during each respiratory cycle), inspiratory reserve volume (volume of gas that can be inhaled after a quiet breath ) and expiratory reserve volume (the volume of gas that can be exhaled after a normal exhalation). After maximum exhalation, a certain amount of air remains in the lungs - the so-called. residual volume (OO). VC and OO together make up the total lung capacity (TLC). The volume of air in the lungs after a quiet exhalation (the sum of the reserve and residual volumes) is called the functional residual capacity (FRC).

The first study of VC in humans was carried out by Hutchinson (J. Hutchinson, 1846), who established the dependence of VC on sex, height, weight and age and the constancy of the value for each person. The dependence of VC on height, weight, sex and age is expressed in the so-called. due ZhEL [Anthony (A. J. Anthony), 1937].

It can be approximately determined by the proper basal metabolism (see basal metabolism). Empirical formulas for calculating due VC (JEL) are also used; for men - according to the formula: 0.052 height - 0.029 age - 3.20 and for women: 0.049 height - 0.019-age - 3.76, where height - in cm, age - in years, JEL - in l.

For children aged 4 to 17 years, the proper values of the vital capacity of the lungs are calculated by the formula (I. S. Shiryaeva, B. A. Markov, 1973): boys JEL (l) \u003d 4.53 height - 3.9, with growth from 1.00 to 1.64 m; JEL (l) \u003d 10.00 height - 12.85, with a height of 1.65 m; girls JEL (l) = 3.75 height - 3.15, with height from 1.00 to 1.75 m.

The definition of VC is widely used in the wedge, and sports medicine. This indicator is the most accessible for measurement and objectively characterizes the functions of external respiration. VC depends on the biomechanical properties of the lungs and chest, and also allows you to indirectly judge the size of the alveolar surface of the lungs. Forster (R. E. Forster) et al. (1957)

A. A. Markosyan (1974) and others found that the more VC, the greater the diffusion capacity of the lungs. The value of VC depends on the position of the body (in a standing position it is greater than in a sitting or lying position).

An increase in VC is observed in the process of physical. workout. A decrease in VC occurs in many diseases accompanied by a weakening of the respiratory muscles, a decrease in the extensibility of the lungs and chest, and venous congestion in the pulmonary circulation.

In violation of bronchial patency and a decrease in lung compliance, VC decreases due to air retention in the lungs and an increase in residual volume.

The measurement of VC is carried out using spirometry, spirography (see), volumemetry and other methods. However, it is more informative to measure VC simultaneously with the measurement of other lung volumes. For this purpose, general plethysmography (see), nitrogenography, the method of diluting helium in a closed system, the radioisotope method, etc. are used. saturation of the atmosphere with water vapor at the time of measurement).

Bibliography: Votchal B. E. and Magazanik N. A. Vital lung capacity and bronchial patency, Klin, medical, t. 47, No. 5, p. 21, 1969; To about mr about DG, etc. Lungs, Clinical and functional tests, the lane with English. from English, M., 1961; Organizational and methodological issues of clinical physiology of respiration, ed. A. D. Smirnova, L., 1973; Rosenblat V. V., Mezenina L. B. and Shmelkova T. M. O due values for assessing the vital capacity of the lungs, Klin, medical, t. 95, 1967; Physiology of respiration, ed. L. JI. Shika et al., p. 4, L., 1973; Functional studies of respiration in pulmonological practice, ed. H. N. Kanaeva, L., 1976; Khasis G. L. Indicators of external respiration of a healthy person, part 1-2, Kemerovo, 1975; Cotes, J. E, Lung function, Oxford-Edinburgh, 1968; Handbook of physiology, ed. by W. O. Fenn a. H. Rahn, sect. 3 - Respiration, v. 1-2, Washington, 1964-1965.

I. S. Shiryaeva.