The vital capacity of the lungs is the largest amount of air. What is VC (vital capacity)

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 procedures

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; based on 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 allows you to find possible violations of bronchial conduction, assess the severity and extent of the identified 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 in 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 intended mainly for the evaluation 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 indications 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 indicators are entered in the diary as a point corresponding to the best of 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 of 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.

Clean the mouthpiece of the spirometer with cotton soaked in alcohol. Let it dry. Set the scale of the dry spirometer to zero.

After 2-3 normal breathing movements, take a maximum breath, pinch your nose and exhale evenly as deeply as possible into the spirometer. Try to stay straight without slouching. Repeat the measurement three times, fix the maximum value of VC.

5. Determine the tidal volume (to) of the lungs using a spirometer

Make a light calm exhalation into the spirometer after a normal breath. For accurate results, repeat the measurements three times and calculate the average value.

At rest, DO ranges on average from 300 to 800 ml.

6. Determine the expiratory reserve volume (RRV) using a spirometer

After the next calm exhalation, exhale as deeply as possible into the spirometer. Repeat the definition three times and calculate the average value.

The average value of ROvyd. equal to 1500 ml.

7. Calculate the inspiratory reserve volume (IRV) using the formula:

Raboutvd. \u003d VC - (DO + ROvyd.)

The average value of ROVD. equal to 1500 - 2500 ml.

8. Calculate the proper lung capacity (DCL) of a student (extra) using the formulas by Ludwig's formula

JEL (female) \u003d 40 × R + 10 × B - 3800;

JEL (male) \u003d 40 × R + 30 × B - 4400

where: JEL- due vital capacity of the lungs, ml,

R- height, cm,

AT– body weight, kg.

For children from 4 to 17 years old, JEL is calculated according to the formula of I.S. Shiryaev and B.A. Markova (1973):

For boys:

JEL (in liters) \u003d 4.53xR - 3.9(with growth up to 1.64 m);

JEL (in liters) =10,00 xp– 3,15 (with growth above 1.64).

For girls:

JEL (in liters) \u003d 3.75xR - 3.15(with growth from 1.00 to 1.75).

R - growth.

9. Calculate the percentage of actual zhel to zhel by the formula:

Normally, the value of the life index (LI) for women is from 45 to 55 ml/kg, for men - 55–60 ml/kg.

The higher the indicator, the better developed the respiratory function of the chest. Lower values indicate either insufficient VC or overweight.

TASKS

TESTS

Question 1. Systolic pressure is ...

The pressure of blood on the walls of blood vessels during ventricular systole.

Blood pressure on the walls of blood vessels during ventricular diastole.

Both options are correct.

Question 2. Optimal-normal systolic blood pressure for adults…

120 - 129 mm. rt. Art.

130 - 139 mm. rt. Art.

100 - 120 mm. rt. Art.

Question 3. Arterial hypertension is observed in systolic blood pressure

100 or less mm. rt. Art.

140 or more mm. rt. Art.

130 - 139 mm. rt. Art.

Question 4. Arterial pulse is ...

Vibrations of the vessel walls during ventricular systole.

Vibrations of the vessel walls during ventricular diastole.

Both options are correct.

Question 5. The duration of the cardiac cycle is ...

Time from one systole to another sitole.

duration of one systole.

The duration of one diastole.

Question 6. The minute volume of blood is ...

The amount of blood ejected by the ventricles at rest.

The amount of blood ejected by the ventricles during exercise.

Question 7. The average value of the IOC for adults ...

2500 - 3000 ml.

4500 - 5000 ml.

Over 6000 ml.

Question 8. Systolic volume is ...

The amount of blood ejected by the ventricles in 1 minute.

The amount of blood ejected by the ventricles in one contraction.

Both options are correct.

Question 9. Pulse pressure is ...

Difference between systolic and diastolic pressure.

Difference between blood pressure in arteries and veins.

Blood pressure in the arteries during ventricular diastole.

Question 10. Diastolic blood pressure is ...

Blood pressure in the arteries during ventricular contraction.

Blood pressure in the arteries during relaxation of the ventricles.

Both options are correct.

Question 11. The vital capacity of the lungs is ...

The maximum volume of air exhaled after a maximum inspiration.

Exhaled volume of air during quiet breathing.

Exhaled volume of air after a quiet exhalation.

Question 12. Tidal volume is ...

The volume of air in the lungs after maximum inspiration.

The volume of air that moves during a quiet inhalation and exhalation.

Exhaled volume of air at maximum exhalation.

Question 13: Inspiratory reserve volume is...

The volume of air inhaled in excess of normal inspiration.

The volume of air exhaled during maximum exhalation.

The volume of air exhaled during a quiet exhalation.

Question 14. Breathing rate is ...

The number of respiratory cycles in 1 hour.

The number of breaths in 1 minute.

Both options are correct.

Question 15. The pulse in people over 18 years old is equal at rest in the room ...

60 - 80 min.

50 - 94 min.

16 - 20 per min.

Question 16. Resting rate at rest in adults is normal ...

20 - 30 per min.

16 - 20 per min.

60 - 80 min.

Literature

Vorobieva E. A., Gubar A. V., Safyannikova E. B. Anatomy and Physiology. – M.: Medicine, 1981. – S. 183–202.

THEME 3.METABOLISM AND ENERGY. FOOD

Sample questions for the lesson

Nutrition is the most important factor in human growth, development and health.

The concept of metabolism and energy.

Features of metabolism and energy in different age groups.

Proteins and protein metabolism.

Fat exchange.

carbohydrate metabolism.

Water and mineral exchange.

Vitamins.

Food industry. Preservatives, food additives, flavorings.

Practical work No. 1
Definition of the main exchange according to the tables

1. Draw table number 1 in a notebook. Complete the table by completing the following tasks of laboratory work No. 1, No. 2 and No. 3.

2. Using a stadiometer and medical scales, determine the height and weight of the body(you can use data from previous completed laboratory work ).

3. Using the Harris-Benedict tables (Tables 2 and 3), determine the basal metabolic rate. Why in part BUT find the desired body weight with the value of the corresponding number of kilocalories of energy. Then in part B find the age horizontally and height vertically, at the intersection of the age and height columns, find the number of kilocalories corresponding to them. Sum these two numbers and get the average statistical value of the normal basal metabolism of the subject of a given age, gender, height, body weight.

When diagnosing pathologies of the respiratory system, a variety of features and indicators are studied. One of these indicators is lung capacity. Otherwise, this indicator is called lung capacity.

This characteristic allows you to understand how the functioning of the chest is implemented. Lung capacity refers to the amount of air that passes through this organ during respiration.

It should be understood that the concept of lung volume includes several other individual indicators. This term is the largest value that characterizes the activity of the chest and lungs, but not all the air that this organ can contain is used by a person in the process of life.

Lung capacity can vary depending on:

age;
gender;
diseases present
his type of employment.

When talking about the volume of the lungs, it means the average value, which doctors usually focus on, comparing the measurement results with it. But, upon detection of deviations, one cannot immediately assume that a person is sick.

It is necessary to take into account many features, such as the circumference of his chest, lifestyle features, past illnesses and other characteristics.

Key indicators and measurement targets

The concept of total lung capacity is characterized by the amount of air that can fit into the lungs of a person. This value is the largest indicator that describes the work of the chest and respiratory organs. But not all air is involved in metabolic processes. For this, a small part of it is enough, the rest turns out to be a reserve.

The value of the total lung capacity is represented by the sum of two other indicators (vital capacity and residual air). Vital capacity is a value that reflects the amount of air that a person exhales when breathing as deeply as possible.

That is, the patient must take a very deep breath and then exhale forcefully to establish this criterion. Residual air is the amount of air that remains in the lungs after an active exhalation.

In other words, in order to find out the total volume of the lungs, it is necessary to find out two quantities - VC and RH. But they are not final either. The value of vital capacity is made up of three more indicators. It:

tidal volume (exactly the air that is used for breathing);
inspiratory reserve volume (his person inhales during active inspiration in addition to the main tidal volume);
expiratory reserve volume (expired during maximum expiration after the main tidal volume has been removed).

If a person breathes calmly and shallowly, then the reserve amount of air is stored in his lungs. It, as well as residual air, is included in an indicator called the functional residual capacity. Only taking into account all these values, it is possible to draw conclusions about the state of the chest and its organs.

These indicators must be known to make the correct diagnosis. An excessive increase or decrease in lung capacity leads to dangerous consequences, so this indicator must be monitored. Especially if there are suspicions of the development of cardiovascular diseases.

Insufficient volume or improper functioning of the respiratory system leads to oxygen starvation, which negatively affects the entire body. If this deviation is not detected in time, irreversible changes may occur, which will greatly complicate the life of the patient.

These indicators allow you to find out how effective the chosen method of treatment is. If the medical effect is correct, these characteristics will improve.

Therefore, performing measurements of this kind is very important in the treatment process. However, one should not think of pathological phenomena only in terms of deviations in these values. They can differ greatly depending on many circumstances that must be taken into account in order to draw the right conclusions.

Features of measurements and indicators

The main method for determining lung volume is spirography. This procedure is performed using a special device that allows you to find out the main characteristics of breathing. Based on them, the specialist can draw conclusions about the patient's condition.

No complex preparation for spirography is required. It is advisable to do it in the morning, before meals. It is necessary that the patient does not take drugs that affect the breathing process in order for the measurements to be accurate.

In the presence of respiratory diseases, such as bronchial asthma, measurements should be taken twice - first without medication, and then after taking them. This will allow you to establish the features of the influence of drugs and the effectiveness of treatment.

Since the patient will have to actively inhale and exhale during the measurement process, he may experience side effects such as headache, weakness. It may also begin to whine the chest. This should not be scary, because it does not pose a danger and passes quickly.

It is very important to know that the volume of the lungs in an adult can be different, and this does not mean that he has a disease. This may be due to his age, characteristics of life, hobbies, etc.

In addition, even under the same circumstances, different people can have different lung volumes. Therefore, in medicine, an average of each studied quantity is provided, which may vary depending on the circumstances.

The average lung capacity of adults is 4100-6000 ml. The value of VC on average ranges from 3000 to 4800 ml. Residual air can occupy a volume of 1100-1200 ml. Certain limits are also provided for other measured quantities. However, going beyond them does not mean the development of the disease, although the doctor may prescribe additional tests.

With regard to these features in men and women, some differences are also observed. The magnitude of these features in females is usually somewhat lower, although this does not always happen. With active sports, lung volume may increase, as a result of measurement, a woman may demonstrate data that is not typical for women.

VITAL CAPACITY

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

Together with the residual volume, i.e. the volume of air remaining in the lungs after the deepest exhalation, the VC forms the total lung capacity (TLC). Normally, VC is about 3/4 of the total lung capacity and characterizes the maximum volume within which a person can change the depth of his breathing. With calm breathing, a healthy adult uses a small part of the VC: inhales and exhales 300-500 ml air (called tidal volume). At the same time, the inspiratory reserve volume, i.e. the amount of air that a person is able to inhale additionally after a quiet breath, and the expiratory reserve volume, equal to the volume of additionally exhaled air after a quiet exhalation, averages about 1500 ml each. During exercise, tidal volume increases by using the inspiratory and expiratory reserves.

VC is determined using spirography. The value of VC normally depends on the sex and age of a person, his physique, physical development, and with various diseases it can significantly decrease, which reduces the ability of the patient's body to adapt to physical activity. 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 using various empirical formulas. So, based on the height of the subject in meters and his age in years (B), JEL (in liters) can be calculated using the following formulas: for men, JEL \u003d 5.2´ height - 0.029´ B - 3.2; for women JEL = 4.9´ height - 0.019´ B - 3.76; for girls from 4 to 17 years old with height from 1 to 1.75 m JEL \u003d 3.75´ height - 3.15; for boys of the same age with growth up to 1.65 m JEL \u003d 4.53´ growth - 3.9, and with growth over 1.65 m-JEL \u003d 10´ height - 12.85.

Exceeding the proper VC values of any degree is not a deviation from the norm; in physically developed people involved in physical education and sports (especially swimming, boxing, athletics), individual VC values sometimes exceed VC by 30% or more. VC is considered reduced if its actual value is less than 80% VC.

Decreased lung capacity most often observed in diseases of the respiratory system and pathological changes in the volume of the chest cavity; in many cases, it is one of the important pathogenetic mechanisms of development respiratory failure . A decrease in VC should be assumed in all cases when the patient's performance of moderate physical activity is accompanied by a significant increase in breathing, especially if the examination reveals a decrease in the amplitude of respiratory oscillations of the chest walls, and according to chest percussion, respiratory excursions of the diaphragm are limited and (and) its high standing . As a symptom of certain forms of pathology, a decrease in VC, depending on its nature, has a different diagnostic value. In practice, it is important to distinguish between a decrease in VC due to an increase in the residual volume of the lungs (redistribution of volumes in the structure of the TEL) and a decrease in VC due to a decrease in the TRL.

Due to the increase in the residual volume of the lungs, VC decreases with bronchial obstruction with the formation of acute pulmonary distention (see. Bronchial asthma ) or emphysema . For the diagnosis of these pathological conditions, a decrease in VC is not a highly significant symptom, but it plays a significant role in the pathogenesis of respiratory failure developing in them. With this mechanism of reducing VC, the total airiness of the lungs and TFR, as a rule, are not reduced and can even be increased, which is confirmed by direct measurement of TFR using special methods, as well as determined percussion by a low position of the diaphragm and an increase in percussion tone above the lungs (up to the “box” » sound), expansion and increase in the transparency of the lung fields according to X-ray examination. A simultaneous increase in residual volume and a decrease in VC significantly reduce the ratio of VC to the volume of ventilated space in the lungs, which leads to ventilation respiratory failure. Increased respiration could compensate for the decrease in VC in these cases, but with bronchial obstruction, the possibility of such compensation is sharply limited due to forced prolonged expiration, therefore, with a high degree of obstruction, a decrease in VC, as a rule, leads to severe hypoventilation of the pulmonary alveoli and the development of hypoxemia. Decreased VC due to acute pulmonary distention is reversible.

The reasons for the decrease in VC due to a decrease in the TEL can be either a decrease in the capacity of the pleural cavity (thoracophrenic pathology), or a decrease in the functioning lung parenchyma and pathological rigidity of the lung tissue, which formulates a restrictive, or restrictive, type of respiratory failure. Its development is based on a decrease in the area of diffusion of gases in the lungs due to a decrease in the number of functioning alveoli. The ventilation of the latter is not significantly disturbed, because the ratio of VC to the volume of the ventilated space in these cases does not decrease, but more often increases (due to a simultaneous decrease in the residual volume); increased breathing is accompanied by hyperventilation of the alveoli with signs of hypocapnia (see. Gas exchange ). From thoracophrenic pathology, a decrease in VC and HL most often cause a high standing of the diaphragm, for example, with ascites obesity (see pickwickian syndrome ), massive pleural effusion (with hydrothorax , pleurisy , mesothelioma pleura ) and extensive pleural adhesions, pneumothorax pronounced kyphoscoliosis. The range of lung diseases accompanied by restrictive respiratory failure is small and includes mainly severe forms of pathology: pulmonary fibrosis in berylliosis, sarcoidosis , Hammen-Rich syndrome (see. Alveolitis ), diffuse connective tissue diseases , pronounced focal-diffuse pneumosclerosis , the absence of a lung (after pulmonectomy) or part of it (after lung resection).

A decrease in TL is the main and most reliable functional and diagnostic symptom of pulmonary restriction. However, prior to the measurement of RCL, which requires special equipment rarely used in polyclinics and district hospitals, the main indicator of restrictive respiratory disorders is a decrease in VC as a reflection of a decrease in RCL. The latter should be considered when a decrease in VC is detected in the absence of pronounced violations of bronchial patency, as well as in cases where it is combined with signs of a decrease in the total air capacity of the lungs (according to percussion and X-ray examination) and a high standing of the lower borders of the lungs. Diagnosis is facilitated if the patient has inspiratory dyspnea, characteristic of restriction, with a short labored inhalation and rapid exhalation at an increased respiratory rate.

In patients with reduced VC at certain intervals, it is advisable to repeat its measurements in order to monitor the dynamics of respiratory functions and evaluate the treatment.