Research methods and indicators of external respiration. Vital capacity of the lungs

Together with the residual volume, i.e. the volume of air remaining in the lungs after the deepest exhalation, vital capacity forms the total lung capacity (TLC). Normally, vital capacity 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. During quiet breathing, a healthy adult uses a small part of vital capacity: inhales and exhales 300-500 ml of air (the so-called tidal volume). In this case, the inspiratory reserve volume, i.e. the amount of air that a person is able to additionally inhale after a quiet inhalation, and the reserve volume of exhalation, equal to the volume of additionally exhaled air after a quiet exhalation, averages approximately 1500 ml each. During physical activity, tidal volume increases due to the use of inhalation and exhalation reserves.

Vital capacity is determined using spirography (Spirography). The value of vital capacity normally depends on the sex and age of a person, his physique, physical development, and when various diseases it can decrease significantly, which reduces the patient’s body’s ability to adapt to physical activity. To assess the individual value of vital capacity, in practice it is customary to compare it with the so-called proper vital capacity (VC), which is calculated using various empirical formulas. So, based on the height of the subject in meters and his age in years (B), VEL (in liters) can be calculated using the following formulas: for men VEL = 5.2×height - 0.029×H - 3.2; for women VEL = 4.9×height - 0.019×H - 3.76; for girls from 4 to 17 years old with a height of 1 to 1.75 m VEL = 3.75 × height - 3.15; for boys of the same age with a height of up to 1.65 m, VEL = 4.53 × height - 3.9, and with a height over 1.65 m - VEL = 10 × height - 12.85.

Exceeding the required VC values of any degree is not a deviation from the norm; in physically developed individuals 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% of VC.

A decrease in the vital capacity of the lungs is 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(Respiratory failure). A decrease in vital capacity 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 percussion of the chest, a limitation in the respiratory excursions of the diaphragm and/or its high standing have been established . As a symptom of certain forms of pathology, a decrease in vital capacity, depending on its nature, has different diagnostic value. It is practically important to distinguish between a decrease in vital capacity due to an increase in residual lung volume (redistribution of volumes in the structure of the lung capacity) and a decrease in vital capacity due to a decrease in the volume of vital capacity.

Due to the increase in residual lung volume, vital capacity decreases with bronchial obstruction with the formation of acute swelling of the lungs (see Bronchial asthma) or pulmonary emphysema (Pulmonary emphysema). To diagnose these pathological conditions a decrease in vital capacity is not a highly significant symptom, but it plays a significant role in the pathogenesis of the respiratory failure that develops with them. With this mechanism for reducing vital capacity, the overall airiness of the lungs and the volumetric capacity, as a rule, are not reduced and can even be increased, which is confirmed by direct measurement of the volumetric capacity using special methods, as well as determined by percussion by the low position of the diaphragm and an increase in the percussion tone above the lungs (up to the “box tone”). » sound), expansion and increase in transparency of the pulmonary fields according to x-ray examination. A simultaneous increase in residual volume and a decrease in vital capacity significantly reduces the ratio of vital capacity to the volume of the ventilated space in the lungs, which leads to ventilation respiratory failure. In these cases, increased breathing could compensate for the decrease in vital capacity, but with bronchial obstruction the possibility of such compensation is sharply limited due to forced prolonged exhalation, therefore, when high degree obstruction, a decrease in vital capacity leads, as a rule, to severe hypoventilation of the pulmonary alveoli and the development of hypoxemia. A decrease in vital capacity due to acute pulmonary inflation is reversible.

The reasons for the decrease in VC due to a decrease in TLC can be either a decrease in the capacity of the pleural cavity (thoracodiaphragmatic pathology), or a loss of 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 impaired, because the ratio of vital capacity 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). Of the thoracodiaphragmatic pathologies, a decrease in VC and TEL is most often caused by a high standing diaphragm, for example, with Ascites, obesity (see Pickwick syndrome), massive pleural effusion (with Hydrothorax, Pleurisy, pleural mesothelioma (Pleura)) and extensive pleural adhesions, Pneumothorax, severe kyphoscoliosis . The range of lung diseases accompanied by restrictive respiratory failure is small and includes mainly severe forms pathologies: pulmonary fibrosis with berylliosis, Sarcoidosis, Hammen-Rich syndrome (see Alveolitis), diffuse diseases connective tissue(Diffuse connective tissue diseases), pronounced focal-diffuse pneumoosclerosis (Pneumosclerosis), absence of a lung (after pneumonectomy) or part of it (after lung resection).

A decrease in TLC is the main and most reliable functional diagnostic symptom of pulmonary restriction. However, before measuring TLC, which requires special equipment that is rarely used in clinics and district hospitals, the main indicator of restrictive breathing disorders is a decrease in vital capacity as a reflection of a decrease in TLC. The latter should be considered when a decrease in vital capacity is detected in the absence pronounced violations bronchial obstruction, as well as in cases when 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 position of the lower borders of the lungs. Diagnosis is facilitated if the patient has inspiratory dyspnea characteristic of restriction with short, difficult inhalation and rapid exhalation at an increased respiratory rate.

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

See also Forced vital capacity (Forced vital capacity).

index external respiration, which is the volume of air leaving the respiratory tract during the maximum exhalation produced after the maximum inhalation.

due (JEL) - calculated indicator to assess the actual J. e. l., determined from data on the age and height of the subject using special formulas.

forced (FVC) - J. e. l., determined with the fastest possible exhalation; Normally it is 90-92% F. e. l., determined in the usual way.

See the meaning of Vital Capacity of the Lungs in other dictionaries

1. The ability to contain a certain amount of something; capacity. E. vessel. Three liter bottle. The astronauts' food is packaged in tubes.

Kuznetsov's Explanatory Dictionary

operations: 1. General

the amount of insurance coverage available in a particular market (e.g.

region, country or world) by type of insurance or.

Document Capacity, Information - the amount of information contained in the document, calculated based on the summation of the weights of semantic descriptors - words and phrases.

livestock that can feed themselves on the land without deteriorating its condition.

operations: 1. Potential insurance

capacity for a certain type of insurance activity of those insurers who usually do not specialize.

sales volume of a certain

goods on the market for a given period

period depending on

demand for goods, price levels, general conditions.

Market Capacity Monetary - a value reflecting the amount of money that can be absorbed by those offered on the market

services; limited by the size of services and the level of production.

Storage Capacity - The maximum possible storage space in a manufacturing warehouse.

Insurance Market Capacity - the volume of sales of insurance policies over a certain period of time, usually a year.

Capacity of the Commodity Market is the volume of goods sold on the market during the year in physical or value terms.

Market Money Capacity is a value that reflects the amount of money that can be absorbed by goods offered on the market, securities and services. Limited by the size of services and the level of production.

Market Capacity - Aggregate consumer demand for goods under certain conditions and for a certain period of time (Order of the Ministry of Trade dated December 14, 1995 N 80)

A specific Life Situation is an element of the mechanism of criminal behavior, including the spatio-temporal objective and personal circumstances of a specific crime.

Large medical dictionary

Actinomycosis of the Lungs - (a. pulmonum) a form of thoracic A., characterized by the development of infiltrates in the lungs, which usually undergo suppuration and decay with the formation of fistulas.

Large medical dictionary

Artificial Ventilation Device - (syn.: A. respiratory, A. artificial respiration, respirator) A. for conducting controlled or auxiliary artificial ventilation of the lungs by forced ventilation.

Large medical dictionary

Pulmonary aspergillosis - (a. pulmonum) visceral A. with damage to the lungs, manifested by hemoptysis, pulmonary hemorrhages, and the formation of aspergillomas.

Large medical dictionary

Blastomycosis of the Lungs - (b. pulmonum) damage to the lungs in the visceral form of Gilchrist's blastomycosis, which has the character focal pneumonia with a tendency to necrosis and suppuration of lung tissue.

Large medical dictionary

Difficult Life Situation - a situation that objectively disrupts the life of a citizen (disability, inability to self-care due to old age, illness, orphanhood.

Brown Lung Compaction - (induratio fusca pulmonum: synonym brown lung induration) diffuse proliferation of connective tissue in the lung with focal deposits of iron-containing brown pigment and abundance.

Large medical dictionary

Lung Ventilation Artificial - (syn. artificial respiration) a method of maintaining gas exchange in the body by periodic artificial movement of air or other gas mixture into the lungs and back into the environment.

Large medical dictionary

Lung Ventilation Artificial Automatic - Ventilation of the lungs, which automatically maintains a given level of carbon dioxide tension in the blood.

Large medical dictionary

Lung ventilation Artificial Asynchronous - V. l. i., in which during the inhalation phase of one lung the exhalation phase of the other lung occurs.

Large medical dictionary

Lung ventilation Artificial Assisted - V. l. And. when the rhythm is maintained, but the volume of natural breathing is insufficient, when an additional volume of gas mixture (air) is pumped into the lungs during inhalation.

Large medical dictionary

Lung ventilation Artificial Electrostimulation - V. l. i., in which inhalation is caused by electrical stimulation of the phrenic nerves or respiratory muscles.

Large medical dictionary

Lung Ventilation Maximum - (mvl) an indicator of the level of respiratory functionality, equal to the maximum minute volume of pulmonary ventilation (i.e. at the highest frequency and depth of respiratory movements).

Large medical dictionary

See more words:

View the Wikipedia article for Vital Capacity of the Lungs

Online dictionaries and encyclopedias in electronic form. Search, meanings of words. Online translator text.

Function of external respiration in chronic bronchitis

Currently clinical physiology breathing is one of the fastest growing scientific disciplines with its inherent theoretical foundations, methods and tasks. The numerous research methods, their increasing complexity and rising costs make it difficult for them to be adopted by practical healthcare. Many new methods for studying various breathing parameters are still under investigation; There are no clear indications for their use, or criteria for quantitative and qualitative assessment.

IN practical work The most common are spirography, pneumotachometry and methods for determining residual lung volume. Complex use These methods allow one to obtain quite a lot of information.

When analyzing a spirogram, tidal volume (TV) is assessed - the amount of inhaled and exhaled air during quiet breathing; respiratory rate per minute (RR); minute volume of respiration (MOV = DO x RR); vital capacity (VC) - the volume of air that a person can exhale after a maximum inhalation; curve of forced vital capacity (FVC), which is recorded when performing a full exhalation with maximum effort from the position of maximum inspiration at high recording speed.

From the FVC curve, the forced expiratory volume in the first second (FEV 1) and maximum pulmonary ventilation (MVL) are determined when breathing with an arbitrary maximum depth and frequency. R. F. Clement recommends performing MVL at a given respiratory volume, not exceeding the volume of the straight part of the FVC curve, and with a maximum frequency.

Measurement of functional residual capacity (FRC) and residual lung volume (RLV) significantly complements spirography, allowing one to study the structure of total lung capacity (TLC).

A schematic representation of the spirogram and the structure of the total lung capacity is shown in the figure.

Schematic representation of the spirogram and structure of the OEL

OEL - total lung capacity; FRC - functional residual capacity; E air - air capacity; ROL - residual lung volume; Vital capacity - vital capacity of the lungs; RO ind - inspiratory reserve volume; RO exhalation reserve volume; DO - tidal volume; FVC - forced vital capacity curve; FEV 1 - one-second forced expiratory volume; MVL - maximum ventilation.

Two relative indicators are calculated from the spirogram: the Tiffno index (the ratio of FEV 1 to VC) and the air velocity index (APSV) - the ratio of MVL to VC.

The analysis of the obtained indicators is carried out by comparing them with the proper values, which are calculated taking into account height in centimeters (P) and age in years (B).

Note. When using the SG spirograph, the required FEV 1 decreases in men by 0.19 l, in women by 0.14 l. In persons aged 20 years, vital capacity and FEV are approximately 0.2 l less than at the age of 25 years; for persons over 50 years of age, the coefficient when calculating the proper international level is reduced by 2.

For the FRC/FLC ratio, a general standard has been established for persons of both sexes, regardless of age, equal to 50 ± 6% [Kanaev N. N. et al., 1976].

The use of the given standards of TLC/TLC, FRC/TLC and VC allows us to determine the proper values of TLC, FRC and TLC.

With the development of obstructive syndrome, there is a decrease in absolute speed indicators (FEV 1 and MVL), exceeding the degree of decrease in VC, as a result of which relative speed indicators (FEV/VC and MVL/VC) decrease, characterizing the severity of bronchial obstruction.

The table shows the normal limits and gradations of deviations in external respiration indicators, which allow you to correctly evaluate the data obtained. However, with severe disturbances of bronchial obstruction, a significant decrease in vital capacity is also observed, which complicates the interpretation of spirography data and the differentiation of obstructive and mixed disorders.

A natural decrease in vital capacity as bronchial obstruction intensifies was demonstrated and substantiated by B. E. Votchal and N. A. Magazanik (1969) and is associated with a decrease in the lumen of the bronchi due to a weakening of the elastic traction of the lungs and a decrease in the volume of all pulmonary structures. The narrowing of the lumen of the bronchi and especially the bronchioles during exhalation leads to such an increase in bronchial resistance that further exhalation is impossible even with maximum effort.

It is clear that the smaller the lumen of the bronchi during exhalation, the sooner they will collapse to a critical level. In this regard, in case of severe disturbances of bronchial obstruction great importance acquires an analysis of the structure of TLC, revealing a significant increase in TLC along with a decrease in VC.

Domestic authors attach great importance to the analysis of the structure of OEL [Dembo A. G., Shapkaits Yu. M., 1974; Kanaev N.N., Orlova A.G., 1976; Clement R.F., Kuznetsova V.I., 1976, etc.] The ratio of FRC and inspiratory capacity (E ind) to a certain extent reflects the ratio of the elastic forces of the lung and chest, since the level of quiet exhalation corresponds to the equilibrium position of these forces. An increase in the FRC in the structure of the TLC in the absence of bronchial obstruction indicates a decrease in the elastic traction of the lungs.

Obstruction of small bronchi leads to changes in the structure of the TLC, primarily an increase in the TLC. Thus, an increase in TRL with a normal spirogram indicates obstruction of the peripheral airways. The use of general plethysmography makes it possible to detect an increase in TBL with normal bronchial resistance (R aw) and to suspect obstruction of small bronchi earlier than determining TBL using the helium mixing method [Kuznetsova V.K., 1978; KriStufek P. et al., 1980].

However, V. J. Sobol, S. Emirgil (1973) point out the unreliability of this indicator for early diagnosis obstructive pulmonary diseases due to large fluctuations in normal values.

Depending on the mechanism of bronchial obstruction, changes in vital capacity and speed indicators have their own characteristics [Kanaev N. N., Orlova A. G., 1976]. When the bronchospastic component of obstruction predominates, TLC increases, despite the increase in TLC, vital capacity decreases slightly compared to speed indicators.

With the predominance of bronchial collapse on exhalation, there is a significant increase in TLC, which is not usually accompanied by an increase in TLC, which leads to sharp decline Vital vital capacity along with a decrease in speed indicators. Thus, we obtain the characteristics of a mixed version of ventilation disorders due to the characteristics of bronchial obstruction.

To assess the nature of ventilation problems, the following rules apply.

Rules used to assess options for ventilation problems [according to Kanaev N.N., 1980]

The assessment is made according to the indicator that is reduced to a greater extent in accordance with the gradations of deviation from the norm. The first two of the presented options are more common in chronic obstructive bronchitis.

With pneumotachometry (PTM), peak (maximum) air flow velocities are determined, which are called pneumotachometric power of inhalation and exhalation (M and M in). Assessing PTM indicators is difficult because the study results are very variable and depend on many factors. Various formulas have been proposed to determine the proper values. G. O. Badalyan proposes to consider the due M equal to 1.2 vital capacity, A. O. Navakatikyan - 1.2 due vital capacity.

PTM is not used to assess the degree of ventilation impairment, but is important for studying patients over time and conducting pharmacological tests.

Based on the results of spirography and pneumotachometry, a number of other indicators are determined, which, however, have not found widespread use.

Gensler air flow speed index: ratio of MVL to proper MVL, %/ratio of vital capacity to proper vital capacity, %.

Amatuni index: Tiffno index/Ratio of vital capacity to vital capacity, %.

Indicators Mvyd/VC and Mvyd/VC, corresponding to the indicators obtained from the analysis of the spirogram FEV 1/VC and FEV 1/VC [Amatuni V. G., Akopyan A. S., 1975].

A decrease in M eq FEV 1 and an increase in R characterize damage to large bronchi (the first 7 - 8 generations).

"Chronic nonspecific lung diseases"

N.R.Paleev, L.N.Tsarkova, A.I.Borokhov

Detection of isolated obstruction peripheral parts bronchial tree is an important problem functional diagnostics breathing, because modern ideas the development of obstructive syndrome begins precisely with damage to the peripheral bronchi and pathological process at this stage we will still reversible. For these purposes, a number of functional methods are used: study of the frequency dependence of lung compliance, volume...

On a regular radiograph chronic bronchitis As a rule, it is not possible to detect symptoms characterizing the actual damage to the bronchi. These negative radiological data are confirmed by morphological studies indicating that inflammatory changes in the bronchial wall are not sufficient to make the bronchi, previously invisible on the radiograph, become visible. However, in a number of cases, it is possible to identify radiological changes associated with...

A diffuse increase in the transparency of the lung fields is considered the most important radiological sign of pulmonary emphysema. B. E. Votchal (1964) emphasized the extreme unreliability of this symptom due to its extreme subjectivity. Along with this, large emphysematous bullae and locally pronounced swelling of individual areas of the lung may be detected. Large emphysematous bullae with a diameter of more than 3 - 4 cm have the appearance of a limited field of increased transparency...

With the development of pulmonary hypertension and chronic cor pulmonale, certain radiological signs appear. The most important of them is a decrease in the caliber of small peripheral vessels. This symptom develops as a result of generalized vascular spasm caused by alveolar hypoxia and hypoxemia, and is a fairly early symptom of impaired pulmonary circulation. Later, the already indicated expansion of the large branches of the pulmonary artery is noted, which creates a symptom...

Bronchographic examination significantly expands the possibilities for diagnosing chronic bronchitis. The frequency of detection of signs of chronic bronchitis depends on the duration of the disease. In patients with a disease duration of more than 15 years, symptoms of chronic bronchitis are detected in 96.8% of cases [Gerasin V. A. et al., 1975]. Bronchographic examination is not mandatory for chronic bronchitis, but is of great importance in diagnosing it...

Ask the doctor!

Diseases, consultations, diagnosis and treatment

External respiration function: research methods

(FVD) – one of the main directions instrumental diagnostics pulmonary diseases. It includes methods such as:

In a narrower sense, the study of physical function is understood as the first two methods, carried out simultaneously using an electronic device - a spirograph.

In our article we will talk about indications, preparation for the listed studies, and interpretation of the results obtained. This will help patients with respiratory diseases to navigate the need for one or another diagnostic procedure and better understand the data obtained.

A little about our breathing

Breathing – life process, as a result of which the body receives oxygen necessary for life from the air and releases carbon dioxide formed during metabolism. Breathing has the following stages: external (with the participation of the lungs), the transfer of gases by red blood cells and tissue, that is, the exchange of gases between red blood cells and tissues.

Gas transfer is studied using pulse oximetry and blood gas analysis. We will also talk a little about these methods in our topic.

The study of the ventilation function of the lungs is available and is carried out almost everywhere for diseases of the respiratory system. It is based on measuring lung volumes and air flow rates during breathing.

Tidal volumes and capacities

Vital capacity of the lungs (VC) is the largest volume of air exhaled after take a deep breath. In practice, this volume shows how much air can “fit” into the lungs during deep breathing and participate in gas exchange. When this indicator decreases, they speak of restrictive disorders, that is, a decrease in the respiratory surface of the alveoli.

Functional vital capacity (FVC) is measured like vital capacity, but only during rapid exhalation. Its value is less than vital capacity due to the decrease at the end of rapid exhalation of the part airways, as a result of which some volume of air remains “unexhaled” in the alveoli. If FVC is greater than or equal to VC, the test is considered as incorrectly performed. If FVC is less than VC by 1 liter or more, this indicates a pathology of small bronchi that collapse too early, preventing air from leaving the lungs.

While performing the rapid exhalation maneuver, another very important parameter is determined - forced expiratory volume in 1 second (FEV1). It decreases with obstructive disorders, that is, with obstacles to the exit of air into the bronchial tree, in particular, with chronic bronchitis and severe bronchial asthma. FEV1 is compared with the proper value or its ratio to vital capacity (Tiffenau index) is used.

A decrease in the Tiffno index of less than 70% indicates severe bronchial obstruction.

The indicator of minute ventilation of the lungs (MVL) is determined - the amount of air passed through the lungs during the fastest and deepest breathing per minute. Normally it is 150 liters or more.

Pulmonary function test

It is used to determine lung volumes and velocities. Additionally, they are often prescribed functional tests, recording changes in these indicators after the action of any factor.

Indications and contraindications

The study of respiratory function is carried out for any diseases of the bronchi and lungs, accompanied by impaired bronchial obstruction and/or a decrease in the respiratory surface:

The study is contraindicated in the following cases:

children under 4–5 years of age who cannot correctly follow the nurse’s commands;
acute infectious diseases and fever;
severe angina, acute period myocardial infarction;
high numbers blood pressure, recent stroke;
congestive heart failure, accompanied by shortness of breath at rest and with slight exertion;
mental disorders that do not allow you to correctly follow instructions.

How the research is carried out

The procedure is carried out in a functional diagnostics room, in a sitting position, preferably in the morning on an empty stomach or no earlier than 1.5 hours after a meal. As prescribed by the doctor, bronchodilators that the patient is constantly taking can be discontinued: short-acting beta2 agonists - 6 hours, long-acting beta2 agonists - 12 hours, long-acting theophyllines - a day before the examination.

Pulmonary function test

The patient's nose is closed with a special clip so that breathing is carried out only through the mouth, using a disposable or sterilizable mouthpiece (mouthpiece). The subject breathes calmly for some time, without focusing on the breathing process.

Then the patient is asked to take a calm maximum inhalation and the same calm maximum exhalation. This is how vital capacity is assessed. To assess FVC and FEV1, the patient takes a calm, deep breath and exhales all the air as quickly as possible. These indicators are recorded three times at short intervals.

At the end of the study, a rather tedious registration of MVL is carried out, when the patient breathes as deeply and quickly as possible for 10 seconds. During this time, you may feel slightly dizzy. It is not dangerous and goes away quickly after stopping the test.

Many patients are prescribed functional tests. The most common of them:

test with salbutamol;
exercise test.

Less often a test with methacholine is prescribed.

When conducting a test with salbutamol, after recording the initial spirogram, the patient is asked to inhale salbutamol, a short-acting beta2 agonist that dilates spasmodic bronchi. After 15 minutes, the study is repeated. You can also use inhalation of the M-anticholinergic ipratropium bromide, in which case the test is repeated after 30 minutes. Administration can be carried out not only using a metered dose aerosol inhaler, but in some cases using a spacer or nebulizer.

A test is considered positive when the FEV1 indicator increases by 12% or more while simultaneously increasing its absolute value by 200 ml or more. This means that the initially identified bronchial obstruction, manifested by a decrease in FEV1, is reversible, and after inhalation of salbutamol, bronchial patency improves. This is observed in bronchial asthma.

If, with an initially reduced FEV1 value, the test is negative, this indicates irreversible bronchial obstruction, when the bronchi do not respond to drugs that dilate them. This situation is observed in chronic bronchitis and is not typical for asthma.

If, after inhalation of salbutamol, the FEV1 indicator decreases, this is a paradoxical reaction associated with bronchospasm in response to inhalation.

Finally, if the test is positive against the background of an initial normal FEV1 value, this indicates bronchial hyperreactivity or hidden bronchial obstruction.

When conducting a load test, the patient performs an exercise on a bicycle ergometer or treadmill for 6–8 minutes, after which a repeat test is performed. When FEV1 decreases by 10% or more, they speak of a positive test, which indicates exercise asthma.

To diagnose bronchial asthma in pulmonology hospitals, a provocative test with histamine or methacholine is also used. These substances cause spasm of the altered bronchi in a sick person. After inhalation of methacholine, repeated measurements are taken. A decrease in FEV1 by 20% or more indicates bronchial hyperresponsiveness and the possibility of bronchial asthma.

How are the results interpreted?

Basically, in practice, the doctor of functional diagnostics focuses on 2 indicators - vital capacity and FEV1. Most often they are assessed according to the table proposed by R. F. Clement et al. Here is a general table for men and women, which shows percentages of the norm:

For example, with a vital capacity of 55% and an FEV1 of 90%, the doctor will conclude that there is a significant decrease in the vital capacity of the lungs with normal bronchial patency. This condition is typical for restrictive disorders in pneumonia and alveolitis. In chronic obstructive pulmonary disease, on the contrary, vital capacity may be, for example, 70% (slight decrease), and FEV1 – 47% (sharply decreased), while the test with salbutamol will be negative.

We have already discussed the interpretation of tests with bronchodilators, exercise and methacholine above.

Another method of assessing external respiration function is also used. With this method, the doctor focuses on 2 indicators - forced vital capacity (FVC) and FEV1. FVC is determined after a deep breath with a sharp full exhalation, lasting as long as possible. In a healthy person, both of these indicators are more than 80% of normal.

If FVC is more than 80% of normal, FEV1 is less than 80% of normal, and their ratio (Genzlar index, not Tiffno index!) is less than 70%, they speak of obstructive disorders. They are associated primarily with impaired bronchial patency and the exhalation process.

If both indicators are less than 80% of the norm, and their ratio is more than 70%, this is a sign of restrictive disorders - lesions of the lung tissue itself that prevent full inspiration.

If the values of FVC and FEV1 are less than 80% of normal, and their ratio is less than 70%, these are combined disorders.

To assess the reversibility of obstruction, look at the FEV1/FVC value after inhalation of salbutamol. If it remains less than 70%, the obstruction is irreversible. This is a sign of chronic obstructive pulmonary disease. Asthma is characterized by reversible bronchial obstruction.

If irreversible obstruction is identified, its severity must be assessed. For this purpose, FEV1 is assessed after inhalation of salbutamol. When its value is more than 80% of the norm, we speak of mild obstruction, 50–79% – moderate, 30–49% – severe, less than 30% of the norm – severe.

Pulmonary function testing is especially important to determine the severity of bronchial asthma before treatment. In the future, for self-monitoring, patients with asthma should perform peak flow measurements twice a day.

Peak flowmetry

This is a research method that helps determine the degree of narrowing (obstruction) of the airways. Peak flowmetry is carried out using a small device - a peak flow meter, equipped with a scale and a mouthpiece for exhaled air. Most Applications Peak flowmetry was used to control the course of bronchial asthma.

How is peak flowmetry performed?

Each patient with asthma should perform peak flow measurements twice a day and record the results in a diary, as well as determine the average values for the week. In addition, he must know his best result. A decrease in average indicators indicates a deterioration in control over the course of the disease and the onset of an exacerbation. In this case, it is necessary to consult a doctor or increase the intensity of therapy if the pulmonologist explained in advance how to do this.

Daily peak flow chart

Peak flowmetry shows maximum speed achieved during exhalation, which correlates well with the degree of bronchial obstruction. It is carried out in a sitting position. First, the patient breathes calmly, then takes a deep breath, takes the mouthpiece of the device into his lips, holds the peak flow meter parallel to the floor surface and exhales as quickly and intensely as possible.

The process is repeated after 2 minutes, then again after 2 minutes. The best of the three indicators is recorded in the diary. Measurements are taken after waking up and before going to bed, at the same time. During the period of selection of therapy or if the condition worsens, additional measurements can be taken during the daytime.

How to interpret the data

Normal values for this method are determined individually for each patient. At the beginning of regular use, subject to remission of the disease, the best indicator of peak expiratory flow (PEF) for 3 weeks is found. For example, it is equal to 400 l/s. Multiplying this number by 0.8, we get the minimum limit of normal values for of this patient– 320 l/min. Anything above this number is in the “green zone” and indicates good asthma control.

Now we multiply 400 l/s by 0.5 and get 200 l/s. This upper limit“red zone” - a dangerous decrease in bronchial patency when necessary urgent help doctor PEF values between 200 l/s and 320 l/s are within the “yellow zone” when therapy adjustment is necessary.

It is convenient to plot these values on a self-monitoring graph. This will give you a good idea of how well your asthma is controlled. This will allow you to consult a doctor in time if your condition worsens, and with long-term good control it will allow you to gradually reduce the dosage of the medications you receive (also only as prescribed by a pulmonologist).

Pulse oximetry

Pulse oximetry helps determine how much oxygen is carried by hemoglobin in arterial blood. Normally, hemoglobin captures up to 4 molecules of this gas, while the saturation of arterial blood with oxygen (saturation) is 100%. As the amount of oxygen in the blood decreases, saturation decreases.

To determine this indicator, small devices are used - pulse oximeters. They look like a kind of “clothespin” that is put on your finger. Available for sale portable devices of this type, they can be purchased by any patient suffering from chronic pulmonary diseases to monitor their condition. Pulse oximeters are also widely used by doctors.

When is pulse oximetry performed in a hospital:

during oxygen therapy to monitor its effectiveness;
in intensive care units for respiratory failure;
after severe surgical interventions;
if you suspect obstructive syndrome sleep apnea– periodic cessation of breathing during sleep.

When can you use a pulse oximeter yourself:

during exacerbation of asthma or other pulmonary disease to assess the severity of your condition;
if sleep apnea is suspected - if the patient snores or is obese, diabetes, hypertension or decreased thyroid function - hypothyroidism.

The oxygen saturation rate of arterial blood is 95–98%. If this indicator, measured at home, decreases, you should consult a doctor.

Blood gas study

This study is carried out in a laboratory and examines the patient's arterial blood. It determines the content of oxygen, carbon dioxide, saturation, and the concentration of some other ions. The study is carried out in severe respiratory failure, oxygen therapy and other emergency conditions, mainly in hospitals, primarily in intensive care units.

Blood is taken from the radial, brachial or femoral artery, then the puncture site is pressed with a cotton ball for several minutes; when puncturing a large artery, a pressure bandage is applied to avoid bleeding. Monitor the patient’s condition after puncture; it is especially important to notice swelling and discoloration of the limb in time; The patient should inform the medical staff if he experiences numbness, tingling or other discomfort in a limb.

Normal blood gas values:

A decrease in PO 2, O 2 ST, SaO 2, that is, oxygen content, in combination with an increase in the partial pressure of carbon dioxide can indicate the following conditions:

weakness of the respiratory muscles;
depression of the respiratory center in brain diseases and poisoning;
airway obstruction;
bronchial asthma;
emphysema;
pneumonia;
pulmonary hemorrhage.

A decrease in these same indicators, but with normal carbon dioxide content, occurs in the following conditions:

Decrease in O 2 ST indicator at normal pressure oxygen and saturation are characteristic of severe anemia and a decrease in circulating blood volume.

Thus, we see that both the conduct of this study and the interpretation of the results are quite complex. An analysis of the blood gas composition is necessary to make a decision on serious medical procedures, in particular, artificial ventilation. Therefore, do it in outpatient setting doesn't make sense.

To learn how to study the function of external respiration, watch the video.

Each breathing 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 inhalation, 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 - adds up to an average of 3500 ml. The vital capacity of the lungs is the volume of air exhaled after intense inhalation and deep exhalation. It can be measured with a spirometer - special device. 3000-5000 ml.

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

The vital capacity of the lungs, determined by a spirometer, is an indicator of restrictive diseases (for example,

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

Breathing process

During quiet 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 respiratory tract. Under the influence of work, the body increases oxidative processes, and the amount of air turns out to be insufficient, i.e., the need for oxygen consumption and carbon dioxide release increases. The vital capacity of the lungs must be increased under these conditions. For normal pulmonary ventilation, the body must increase the respiratory rate and the volume of inhaled air. With a sharp increase in breathing, it becomes shallow, and only small part air reaches the pulmonary alveoli. Deep breathing improves pulmonary ventilation and proper gas exchange occurs.

Prevention of lung diseases

Sufficient vital capacity of the lungs is a very important factor that helps maintain human health and good performance. Correctly developed to a certain extent ensures normal breathing, so it is very important morning exercises, sports, physical education. They contribute to the harmonious physical development of the body and the 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 indoor spaces, saturated with water vapor and carbon dioxide, has a Negative influence on the breathing process. The same can be said about smoking, inhaling dust and contaminated particles.

Health-improving measures include landscaping cities and residential areas, paving and watering streets, installing smoke extractors in enterprises, and ventilation absorbing devices in homes.

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

What affects lung capacity?

The level of filling of the lungs with air is influenced by certain circumstances. Men have a larger average organ volume than women. U tall people with a large body constitution, the lungs can hold more air when inhaling than those of short and thin people. With age, the amount of air inhaled decreases, which is a physiological norm.

Systematic smoking reduces lung capacity. Low filling capacity is typical for hypersthenics (short people with a rounded body and short, wide-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 thin, low-density air.

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 and puts pressure on the diaphragm. On general state women are not affected by this, as they turn on compensatory mechanisms. Due to accelerated ventilation, they prevent the development of hypoxia.

Average lung volumes

Lung volume is measured in liters. Average values are calculated during normal breathing at rest, without deep inhalations and full exhalations.

The average figure is 3-4 liters. In physically developed men, the volume during moderate breathing can reach up to 6 liters. The normal number of respiratory acts is 16-20. With active physical activity and nervous strain, these numbers increase.

Vital capacity, or vital capacity of the lungs

The vital capacity is the greatest capacity of the lung during maximum inhalation and exhalation. In young people healthy men the indicator is 3500-4800 cm 3, for 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.

Taking into account the phases of lung ventilation, the following types of volume are divided:

respiratory - air that circulates freely through the bronchopulmonary system at rest;
reserve during inhalation - air filled with the organ during maximum inhalation after a quiet exhalation;
exhalation reserve - the amount of air removed from the lungs during a sharp exhalation after a calm inhalation;
residual - air remaining in the chest after maximum exhalation.

Airway ventilation refers to gas exchange for 1 minute.

The formula for determining it is:

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

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

Table of indicators of the average lung volume:

The air that is located 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”, which is 150-200 cm 3 .

Vital capacity measurement method

External respiratory function is examined using a special test - spirometry (spirography). The method records not only the capacity, but also the speed of air flow circulation.
For diagnostics, digital spirometers are used, which replaced mechanical ones. The device consists of two devices. Sensor for recording air flow and electronic device, which converts measurement indicators into a digital formula.

Spirometry is prescribed to patients with disorders respiratory function, bronchopulmonary diseases chronic form. Calm and forced breathing are assessed, and functional tests are performed with bronchodilators.

Digital data of vital fluid during spirography are distinguished by age, gender, anthropometric data, and the absence or presence of chronic diseases.

Formulas for calculating individual vital capacity, 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 a height of up to 165 cm – 4.53×P – 3.9; with height over 165 cm – 10×P – 12.85;
for girls from 4 to 17 years old the swarm grows from 100 to 175 cm - 3.75×P - 3.15.

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

Diagnostics are not prescribed if it is physically impossible to carry out the test:

neuromuscular disease with fatigue striated facial muscles (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 vital capacity indicators

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

Respiratory function is considered impaired if a person’s lung capacity is less than 80%. This is the first signal of insufficiency of the bronchopulmonary system.

External signs of pathology:

breathing problems during active movements;

change in chest amplitude.

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 cases of pulmonary emphysema and bronchial asthma. During the course of the disease, swelling of the lungs is formed. Therefore, for diagnostic purposes, percussion is performed (low position of the diaphragm, specific “boxy” sound), chest x-ray (more transparent lung fields, expansion of boundaries).

Factors reducing vital capacity:

reduction in the volume of the pleural cavity due to the development of the cor pulmonale;
rigidity of the organ parenchyma (hardening, limited mobility);
high position of the diaphragm with ascites (accumulation of fluid in abdominal cavity), obesity;
pleural hydrothorax (effusion in the pleural cavity), pneumothorax (air in the pleural layers);
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 an organ).

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

Questions at the beginning of the paragraph.

Question 1. How is the condition of the respiratory system determined?

When you inhale and exhale, the chest rises and falls, and therefore its girth changes. In the state of inhalation it is greater, in the state of exhalation it is less. The change in chest circumference during inhalation and exhalation is called chest excursion. The larger it is, the more the chest cavity can be enlarged, and the lungs can take in more air.

Question 2. What does the vital capacity of the lungs indicate?

Question 3. How can tuberculosis and lung cancer be detected at an early stage of the disease?

Tuberculosis and lung cancer on early stages can be detected using fluorography. Every person should undergo fluorography at least once every two years. Persons whose work involves people, as well as students, must undergo fluorography annually.

Question 4. What should be done if the victim has trouble breathing?

Suffocation can occur when the throat is compressed or the tongue retracts. The latter often happens with fainting, when a person suddenly loses consciousness. Therefore, first of all, you need to listen to his breathing. If it is accompanied by wheezing or stops altogether, it is necessary to open the victim’s mouth and pull his tongue forward or change the position of his head, throwing it back. It's good to give it a sniff ammonia. This stimulates the respiratory center and helps restore breathing.

Questions at the end of the paragraph.

Question 1. What is the vital capacity of the lungs? What does this indicator mean?

The vital capacity of the lungs is the largest amount of air that a person can exhale after taking the deepest breath. It is approximately equal to 3500 cm3. The vital capacity of the lungs is greater in athletes than in untrained people, and depends on the degree of development of the chest, gender and age. Under the influence of smoking, the vital capacity of the lungs decreases. Even after the maximum exhalation, there is always some air left in the lungs, which is called residual volume (about 1000 cm3).

Question 2. What lung diseases can be detected using fluorography?

Using fluorography, it is possible to detect tuberculosis and lung cancer.

Question 3. How does pulmonary tuberculosis manifest? How is Koch's bacillus, the causative agent of tuberculosis, spread?

When the causative agent of tuberculosis, Koch's bacillus, enters the lungs, a primary focus of inflammation develops, which is expressed in the appearance of symptoms of normal inflammation. But unlike a banal infection inflammatory process with tuberculosis it develops very slowly (this chronic infection, lasting for years) and is prone to necrosis of the primary focus of inflammation. The complaints of patients are very diverse. Conventionally, they can be divided into nonspecific: malaise, weakness, fever, poor appetite, weight loss, pale skin and others; and specific (mainly characteristic of tuberculosis): sweating at night and in the morning (as manifestations of intoxication that debilitate the patient), temperature ranges between morning and evening by no more than 0.5 degrees, obsessive prolonged cough, etc. Mycobacterium tuberculosis ( Koch bacillus) is transmitted mainly by airborne droplets, entering the respiratory system from a sick person to a healthy one.

Question 4: What factors contribute to lung cancer? What is this disease expressed in?

Most important factor, contributing to the emergence lung cancer, is smoking. IN tobacco smoke contained a large number of carcinogenic substances. Smoking causes lung cancer in approximately 90% of cases. Long-term exposure to carcinogens during long-term smoking leads to disruption of the structure and function of the bronchial epithelium, transformation of columnar epithelium into multilayered squamous epithelium and contributes to the occurrence of a malignant tumor. The tumor grows, which leads not only to obvious negative local impact, but also a depressing effect on the vital functions of the body as a whole, leading to its extreme exhaustion and can be fatal.

Question 5. What are the first aid techniques for rescuing a drowning person?

After removing a drowning person from the water, his respiratory tract must be cleared of water. To do this, the victim is placed with his stomach on his knee and his stomach and chest are squeezed with sharp movements. Then, if necessary, apply artificial respiration.

Question 6. What consequences can occur if the victim is covered with earth? What first aid should he receive?

Victims who are covered in earth may experience suffocation when their throats are compressed and soil enters their nose and mouth. After removing a person from the rubble, it is necessary to restore his breathing: clear his mouth and nose of dirt, perform artificial respiration, and indirect cardiac massage. It is important to warm the patient by rubbing the skin, wrapping him in warm clothes, and drinking hot drinks.

Question 7. Why are lightning and technical electric shock combined into one concept - “electrical injury”?

Lightning and technical electric shock are combined into one concept - “electrical injury”, since they have the same nature and cause similar disturbances.

Question 8. What is the difference between biological and clinical death?

Biological death is associated with brain death and is irreversible, while clinical death is reversible, since with it the human brain still functions, even if breathing stops and the patient’s heart stops.

Question 9. How is artificial respiration performed using mouth-to-mouth and mouth-to-nose methods?

Artificial respiration using the mouth-to-mouth method. The victim is placed face up on a hard surface, with a cushion placed under the neck. It is necessary to kneel near the victim’s head, holding it in the maximum backward position with one hand, thumb pull the other hand lower jaw. The one who provides assistance takes a deep breath, then directly or through gauze tightly covers the victim’s mouth with his lips and exhales sharply. The victim's nose is covered with the fingers of the hand on the forehead. Exhalation is performed by passively reducing the volume of the victim’s chest. The duration of inhalation should be 2 times less than the time required for exhalation. The frequency of oxygen injection into the victim’s lungs is 12–14 times per minute.

Artificial respiration using the mouth-to-nose method. This method is used when the victim’s jaws are tightly clenched or the required expansion of the chest does not occur when using the mouth-to-mouth method. The victim’s head is also tilted back as much as possible and is held with one hand, which lies on the crown of the victim; the other hand should cover the mouth. The person providing assistance takes a deep breath and covers the victim’s nose with his lips and blows. If the chest does not fall enough when exhaling, then it is necessary to open the victim’s mouth slightly.

Indicators of the effectiveness of artificial respiration are expansion of the chest and the appearance of a pink tint to the skin.

Question 10. How is indirect cardiac massage performed?

The victim is placed on a hard surface - the floor, the ground, a table. The person providing assistance is positioned to the side of the victim. Places his palms (overlaid on one another) on the lower part of the victim’s chest (two fingers above the xiphoid process of the sternum). Your arms should be straight at the elbows. Due to the weight of his body, he presses on the victim’s chest, trying to bend it towards the spine by 4–5 cm. Then he leans back and repeats the push-like pressure again. Pressing frequency is 50–70 times per minute.

One of the main methods for assessing the ventilation function of the lungs, used in the practice of medical and labor examination, is spirography, which allows one to determine statistical lung volumes - vital capacity of the lungs (VC), functional residual capacity (FRC), residual lung volume, total lung capacity, dynamic pulmonary volumes - tidal volume, minute volume, maximum ventilation.

Vital capacity of the lungs (VC)- the amount of air that can be exhaled after taking the deepest breath possible. The test is repeated at short intervals (15 seconds) at least three times after one or two test exhalations. Usually the highest value obtained is recorded. Some authors recommend using the average of three measurements.

Vital capacity of the lungs, in addition to height, with which it increases linearly, it also depends on age, with which it decreases linearly, as well as gender and training. Therefore the absolute values vital capacity are not very representative due to large individual differences.

When estimating the value vital capacity, as well as many other respiratory indicators, they use the “proper” values that are obtained when processing the examination results healthy people and establishing correlations with age, height and other factors. The definition of the proper value according to Anthoni is widespread, which is based on the determination of the proper exchange, the value of which is multiplied by the corresponding coefficients.

However vital capacity does not adjust for body weight, which is taken into account when determining basal metabolic rate. More accurate are the formulas proposed N.N. Kanaev:

JEL(BTPS) = 0.52 x height - 0.028 x age - 3.20 (for men);

JEL(BTPS) = 0.049 x height –– 0.019 x age –– 3.76 (for women).

vital capacity expressed as a percentage of normal values. Values vital capacity according to most authors, fluctuate within ±20%, while some authors believe vital capacity pathological only when the value is below 70%.

Decline vital capacity practically can be observed in various lung diseases. vital capacity reduced with emphysema, pneumonia, shrinkage of the lungs, pleural cords, and plastic surgery.

The reason for the decline vital capacity There may be extrapulmonary factors:

- left heart failure(due to venous stagnation in the pulmonary capillaries and loss of elasticity of the lung tissue),

- chest rigidity, insufficiency of the respiratory muscles.

The components that make up vital capacity, are tidal volume (TI), inspiratory reserve volume (IR ind) And expiratory reserve (RO exhalation).

The reserve volume is about half vital capacity, together with tidal volume - about 75% vital capacity. The inspiratory reserve volume decreases when the lungs lose elasticity or chest. Normal expiratory reserve volume is about 25% vital capacity, a strong decrease is observed in emphysema.