Determination of the presence and frequency of respiration. Normal respiratory rate in an adult per minute is normal

Counting respiratory movements is a standard point in examining a child by a pediatrician. Despite the apparent simplicity and obviousness of this manipulation, NPV can provide important information about how healthy the baby is and whether everything is okay with him. Since the number of breaths per minute in children is much higher than in adults, a special table of respiratory rate norms has been developed for them.

The respiratory system of babies and its features

The first opening of the lungs in a newborn occurs immediately after the baby is born. By this time, the child’s respiratory system is not yet fully developed and has a number of features. Thus, babies have narrow and short nasal passages, which cannot always cope with full breathing. The respiratory system tailored for breastfeeding does not allow children to breathe through their mouths, so they may develop shortness of breath and blockage of the nasal passages.

A small child is not yet able to independently clear the nasal passages by blowing his nose, so for normal breathing he especially needs the care and attention of an adult.

Interesting: During sleep, babies may hold their breath during the transition from REM sleep to slow sleep and back, this is completely normal.

How to calculate NPV correctly

This is the simplest procedure that can be done at home. It only requires a stopwatch and the baby at rest, otherwise the data will be unreliable. The ideal time to calculate NPV would be sleep, since crying or restlessness of the child can distort the results of the study.

You can measure the baby's respiratory rate visually, by movements of the chest, or by placing your palm on it. An older child can be held by the wrist (under the base of the thumb) and, watching the pulse, count the number of inhalations and exhalations.

Normal respiratory rate in children

The table shows the average values of normal respiratory rate in children from 0 to 12 years old. In the future, the norm of the child’s respiratory rate coincides with the norm of an adult.

The table clearly shows that respiratory rate decreases with age, while the breathing rate does not depend on a person’s gender. This is due to the fact that with age the respiratory system gradually strengthens, changing at each stage of development.

What does the NPV data say?

If, after correctly measuring the respiratory rate, you find that the child’s breathing is rapid or difficult, you should immediately consult a doctor. This may indicate both disorders in the respiratory system and the presence of an infectious disease.

At the same time, increased breathing during physical activity, increased emotionality, or a child’s enthusiasm for some activity is completely normal and does not require contacting a specialist.

Indications:

Healthy people to assess the state of the respiratory system;

Respiratory diseases.

Contraindications: No.

Equipment:

Clock with second hand or stopwatch

Temperature sheet

Pen with a blue rod.

Patient preparation:

The calculation of respiratory rate is carried out without informing the patient about the respiratory rate study.

Nurse training and workplace safety:

Specialist. clothing: robe, cap, second shoes

Personal protective equipment: gloves, mask (during a flu epidemic)

Manipulation progress:

1. Wash and dry your hands.

2. Place the patient in a comfortable sitting or lying position so that you can see the upper chest.

3. Hold the patient's hand as you would for a radial pulse so that the patient thinks you are examining the pulse.

4. Look at the chest: you will see how it rises and falls. If this is not visible, then place your hand on the chest (for thoracic breathing) or epigastric region (for abdominal breathing) of the patient, simulating a pulse examination.

5. Count the frequency for 1 minute (only the number of breaths) using a stopwatch.

7. Explain to the patient that his respiratory rate has been calculated and inform the patient of the results of the study.

8. Record your result on the temperature sheet.

Processing of the workplace and tools: No.

Nurse safety precautions after the end of the manipulation: Wash and dry your hands.

Complications: No.

Assessment of achieved results: The pulse is calculated and the data is entered into the temperature sheet.

Remember:

Normally, the respiratory rate is 16–20 per minute, with women 2–4 breaths more often than men. When body temperature rises by 1 degree, breathing becomes more frequent by an average of 4 respiratory movements.

Increased NPV – tachypnea.

Decrease in NPV – Bradypnea.

Stopping breathing - apnea.

In a healthy person, three physiological factors can be distinguished: type of breathing depending on gender: abdominal breathing – more common in men; chest breathing - in women, mixed breathing - in children.

Distinguish between breathing superficial And deep . The superficial may be inaudible at a distance or slightly audible. It is often combined with a pathological increase in breathing. Deep breathing, audible from a distance, is often associated with a pathological decrease in breathing.

When the rhythm and depth of breathing is disturbed, shortness of breath occurs. Dyspnea – subjective feeling of lack of air.

1. Physiological– in healthy people after physical activity;

2. Pathological– for various diseases:

A) inspiratory– difficulty breathing

b) expiratory– difficulty exhaling

V) mixed– difficulty inhaling and exhaling.

Rapidly developing shortness of breath is called suffocation.

Pathological types of breathing:

1. Kussmaul breathing – rare, deep, noisy, observed in deep coma.

2. Biotta's Breath - periodic breathing, in which there is a correct alternation of periods of shallow respiratory movements and pauses of equal duration (from several seconds to a minute).

3. Cheyne-Stokes breathing – characterized by a period of increasing frequency and depth of breathing, which reaches a maximum on the 5th-7th breath, followed by a period of decreasing frequency and depth of breathing and another long pause of equal duration (from several seconds to a minute). During the pause, patients are poorly oriented in the environment or lose consciousness, which is restored when breathing movements are resumed.

Related information:

B. A prism absorbs white light of one wavelength and emits light of different wavelengths. D. A prism absorbs white light of one frequency and emits light of different frequencies.

We think you don't often pay attention to how many breaths you take per minute. For healthy adults, such a value as respiratory rate is not very relevant. What cannot be said about newborns: it is not for nothing that the respiratory rate in children is one of the most important indicators of well-being and development, allowing one to monitor and respond in a timely manner to various diseases and pathologies.

How and why should NPV be calculated?

Let's start with the fact that during any therapeutic examination, doctors check the newborn's respiratory rate along with the pulse: that's how important this value is in assessing the condition of babies. The fact is that the baby will not be able to tell you that something is wrong with him, and sometimes a deviation in the breathing rate is the only sign of a developing disease. But before you draw any conclusions about the health of your baby, you need to learn how to collect this information.

When calculating the respiratory rate of an infant, it is important to observe several points so that the data is reliable, but otherwise the procedure is elementary and will take literally a minute.

Count your breathing rate only at rest. If the child is actively spinning, crawling or walking, breathing will be rapid. If the baby is nervous, overexcited or crying, the breathing rate will also increase. It will be easiest to determine the value in a dream, when nothing will distort the information.
Count the number of breaths per minute. If you count the breaths over 30 seconds and multiply by 2, the information may be incorrect due to the arrhythmic breathing characteristic of newborns.
When counting, you do not need to use any additional devices. In infants, the movements of the chest and diaphragm are clearly visible, so you can calculate the respiratory rate in a newborn without even touching him.

Having received the data, you may panic: there are unrealistic numbers, arrhythmia, and incomprehensible delays in breathing! Should I sound the alarm and go to the doctor or is the situation developing within normal limits?

Ideal layout

Of course, there is a certain established norm of breathing rate for different ages, which we will present below in the form of a table, and it is from this information that you can build on when assessing the baby’s condition. So, if a newborn up to one year old has a respiratory rate of 50 breaths per minute, then there is no need to worry, but if we are talking about a two-year-old child at rest, then this is no longer normal.

But proper breathing includes not only a quantitative, but also a qualitative factor, which is usually not included in the table. It is believed that optimal breathing is mixed: this is when a child can switch from chest to abdominal type and back. This way the lungs are ventilated as much as possible, which prevents the establishment of an environment favorable for the proliferation of harmful microorganisms. It’s just worth considering that for newborns, breathing with the diaphragm is more typical than breathing with the chest, so panic in case of insufficient manifestation of the latter will be unjustified.

In addition, we are accustomed to the fact that breathing correctly means taking a deep, smooth breath and exhaling measuredly, and, of course, this arrangement is ideal for babies. But due to the peculiarities of the body of newborns, such a picture is quite rare, and deviations from the norm “deep inhalation - smooth exhalation” make parents worry and worry. But is it worth it?

The nasal passages in newborns are narrow and easily clogged, and babies cannot breathe through their mouths, which leads to shortness of breath, sniffling and wheezing, especially during sleep. This is why it is so important to clean babies’ noses from dust and dirt and to prevent severe swelling of the mucous membrane.

Is periodic breathing dangerous?

Cheyne-Stokes syndrome, or periodic breathing, is typical for premature babies, although it is also common in those born at term. With this respiratory process, the baby breathes rarely and shallowly, then moves on to more frequent and deep breaths, after reaching peak inhalation, he again breathes less frequently and shallowly, and then there is a short delay. From the outside it may seem that this is some kind of attack, and the child urgently needs help, but if you move away from the concept of the “adult” norm, it turns out that there is nothing terrible here. Usually this type of breathing levels out somewhat by the month, and by the year there is no trace left of it. But how many nerves periodic breathing takes away from unprepared parents!

Even when there is no health problem, rapid breathing in a newborn means that the baby is breathing shallowly, which means that the lungs are not ventilated thoroughly enough.

Risks of rapid, infrequent breathing and pauses

If frequent, abdominal and even arrhythmic breathing in children is the norm, then how can you understand that a problem has arisen and not miss the moment?

Rapid breathing (tachypnea) will be considered critical if it deviates from the age norm by 20%. This condition may indicate a number of diseases: from colds, flu, false croup and bronchitis to serious infections, as well as pulmonary and cardiac pathologies. In most cases, the rapid breathing that you should be concerned about will be accompanied by shortness of breath or wheezing from your baby.

Slow breathing (bradypnea) is unusual for infants. If you count fewer breaths than normal, this may be a sign of developing meningitis, but most likely your baby is growing and the baby's breathing rate is decreasing because of this. Again, we can talk about a slowdown only if the indicators are 20% below the age norm.

Holding your breath (apnea) is an absolutely normal phenomenon, especially when it comes to periodic breathing, but it should not exceed 10-15 seconds. If the baby does not breathe for more than 20 seconds and the attack is accompanied by pallor, an arrhythmic pulse and blue discoloration of the fingertips and lips, then you should immediately call an ambulance: this situation is far from normal, and the child needs an examination.

If a child was born premature, it is better to immediately learn how to act in case of apnea, so as not to fall into a stupor when he stops breathing for a while. If you do not place your baby on his back during sleep and know basic techniques for provoking inhalation, such as a simple massage or sprinkling with cold water, such moments will not cause much trouble for either the baby or you.

How many breaths your baby takes per minute should definitely be monitored on a regular basis. Of course, only you will have to decide whether you can handle it yourself or call a doctor, but we hope the information in the article will help you make the right decision.

Breathing is a physiological marker of the state of our body. As adults, we don’t pay much attention to it, but it’s a different matter if it’s a child or a newborn baby.

Every child is subject to difficulties inherent to his age. Runny nose, colds, and bronchopulmonary diseases at this age often develop unnoticed, because the baby often cannot say that something is bothering him or hurting somewhere.

However, many diseases can be detected in the early stages if you pay attention to the baby’s breathing.

Features of the process in children

In infancy and childhood, almost all body systems differ markedly from those of an adult.

When a baby is born, his lungs and chest have different proportions than those of an adult. The baby's chest grows faster than the lungs, and only in an adult does it acquire the size at which fully expanded lungs fit into a relaxed chest.

In children, the lungs do not fully expand even when the chest is fully raised during inhalation. In order for the child’s body to receive the required amount of oxygen, the body is forced to breathe at an increased frequency. Therefore, the respiratory rate in newborns is the highest among all age groups.

Another feature of infants’ breathing: about 70% of them, up to the age of 3-6 weeks, breathe only through the nose. And only 30% immediately breathe through their nose and mouth. This doesn't mean that children who breathe through their noses can't breathe through their mouths, just that they don't do it in their normal, calm state.

In the first months of a baby’s life, his nasal passages are anatomically narrow, and the mucous surfaces of the respiratory tract are supplied with blood to a much greater extent than in adults. This property of the mucous membrane is very useful for the baby, because it allows cold and dry air to enter the lungs already warmed and moistened, cleared of dust and harmful microbes.

But besides the advantages, breathing through the nose also has its disadvantages. The narrowness of the nasal passages due to inflammation, swelling of the mucous membranes or nasal congestion does not allow the child to take a full breath. Any speck that gets into the nose can cause sneezing and mucus accumulation. The baby's breathing becomes difficult, becomes shallow and frequent, and his sleep and feeding are disrupted. The baby becomes restless and begins to scream, thereby ensuring the required amount of air enters the lungs.

The functioning of a newborn's pulmonary system largely depends on the functioning of its diaphragm. This muscle separates the chest cavity from the abdominal cavity and, due to its contractions, ensures the respiratory movements of the lungs. Therefore, problems with the gastrointestinal tract, as well as tight swaddling of the baby, which limits the mobility of his diaphragm, affect the frequency of his respiratory movements.

At an older age, children already breathe largely due to the intercostal muscles and abdominal muscles.

Sometimes infants have a type of breathing in which regular inhalations and exhalations alternate with irregular ones. This is the norm for this age.

A baby's unusual breathing in itself should not be a cause for concern. Shallow, jerky breaths with wheezing or an unstable rhythm are a fairly common phenomenon, although they are some kind of deviation.

Normal frequency

Knowing the child's breathing standards, parents can pay closer attention to his health. The normal respiratory rate in children gradually decreases by age as the baby grows.

Below is a table showing what the normal breathing rate is for children of different ages.

For comparison, in adults the breathing rate is approximately 12-20 breaths per minute.

If your child's breathing rate falls within the range noted above, there is no reason to worry. If breathing becomes faster, this may be an indication of problems and is a reason to immediately consult a doctor.

Possible causes of problems with the respiratory system:

1. Infection;
2. Respiratory distress syndrome;
3. Transient tachypnea of newborns;
4. Other problems (pneumonia, lung malformation, etc.).

Dependence on body temperature

Research shows that the heart rate of babies 2 months and older increases by approximately 10 beats per minute for every degree Celsius increase in body temperature. In children under 2 months of age, this does not occur due to insufficient activation of nervous system regulators to adequately respond to elevated temperature.

Increased temperature stimulates the respiratory muscles and causes increased work of the pulmonary system. Frequent inhalations and exhalations allow heat to be more actively removed through pulmonary gas exchange.

The breathing rate of children under 12 months of age increases by 7-11 breaths per minute for every degree Celsius increase in body temperature. For children under 2 years of age, this figure decreases and is already 5-7 breaths per minute per 1 degree Celsius.

It should be noted that body temperature has a moderate, albeit significant effect on respiratory status, regardless of age group. The application of the obtained data in clinical practice is limited, since the nature of the relationship between respiratory rate and body temperature is not linear.

The entire complex process can be divided into three main stages: external respiration; and internal (tissue) respiration.

External breathing- gas exchange between the body and the surrounding atmospheric air. External respiration involves the exchange of gases between atmospheric and alveolar air, as well as pulmonary capillaries and alveolar air.

This breathing occurs as a result of periodic changes in the volume of the chest cavity. An increase in its volume provides inhalation (inspiration), a decrease - exhalation (expiration). The phases of inhalation and subsequent exhalation are . During inhalation, atmospheric air enters the lungs through the airways, and when exhaling, some of the air leaves them.

Conditions necessary for external respiration:

chest tightness;
free communication of the lungs with the surrounding external environment;
elasticity of lung tissue.

An adult takes 15-20 breaths per minute. The breathing of physically trained people is rarer (up to 8-12 breaths per minute) and deeper.

The most common methods for studying external respiration

Methods for assessing respiratory function of the lungs:

Pneumography
Spirometry
Spirography
Pneumotachometry
Radiography
X-ray computed tomography
Ultrasonography
Magnetic resonance imaging
Bronchography
Bronchoscopy
Radionuclide methods
Gas dilution method

Spirometry- a method of measuring the volume of exhaled air using a spirometer device. Various types of spirometers with a turbimetric sensor are used, as well as water ones, in which exhaled air is collected under a spirometer bell placed in water. The volume of exhaled air is determined by the rise of the bell. Recently, sensors sensitive to changes in volumetric air flow velocity connected to a computer system have been widely used. In particular, a computer system such as “Spirometer MAS-1”, produced in Belarus, etc., operates on this principle. Such systems make it possible to carry out not only spirometry, but also spirography, as well as pneumotachography).

Spirography - a method of continuously recording the volumes of inhaled and exhaled air. The resulting graphical curve is called spirophamma. Using a spirogram, you can determine the vital capacity of the lungs and tidal volumes, respiratory rate and voluntary maximum ventilation of the lungs.

Pneumotachography - method of continuous recording of the volumetric flow rate of inhaled and exhaled air.

There are many other methods for studying the respiratory system. Among them are plethysmography of the chest, listening to sounds produced when air passes through the respiratory tract and lungs, fluoroscopy and radiography, determination of the oxygen and carbon dioxide content in the exhaled air flow, etc. Some of these methods are discussed below.

Volume indicators of external respiration

The relationship between lung volumes and capacities is presented in Fig. 1.

When studying external respiration, the following indicators and their abbreviations are used.

Total lung capacity (TLC)- the volume of air in the lungs after the deepest possible inspiration (4-9 l).

Rice. 1. Average values of lung volumes and capacities

Vital capacity of the lungs

Vital capacity of the lungs (VC)- the volume of air that a person can exhale with the deepest, slowest exhalation made after a maximum inhalation.

The vital capacity of the human lungs is 3-6 liters. Recently, due to the introduction of pneumotachographic technology, the so-called forced vital capacity(FVC). When determining FVC, the subject must, after inhaling as deeply as possible, make the deepest forced exhalation possible. In this case, exhalation should be made with an effort aimed at achieving the maximum volumetric speed of the exhaled air flow throughout the entire exhalation. Computer analysis of such forced exhalation makes it possible to calculate dozens of indicators of external respiration.

The individual normal value of vital capacity is called proper lung capacity(JEL). It is calculated in liters using formulas and tables based on height, body weight, age and gender. For women aged 18-25, the calculation can be made using the formula

JEL = 3.8*P + 0.029*B - 3.190; for men of the same age

Residual volume

JEL = 5.8*P + 0.085*B - 6.908, where P is height; B—age (years).

The value of the measured VC is considered reduced if this decrease is more than 20% of the VC level.

If the name “capacity” is used for the indicator of external respiration, this means that the composition of such a capacity includes smaller units called volumes. For example, TLC consists of four volumes, vital capacity - of three volumes.

Tidal volume (TO)- this is the volume of air entering and leaving the lungs in one respiratory cycle. This indicator is also called the depth of breathing. At rest in an adult, the DO is 300-800 ml (15-20% of the VC value); one month old baby - 30 ml; one year old - 70 ml; ten years old - 230 ml. If the depth of breathing is greater than normal, then such breathing is called hyperpnea- excessive, deep breathing, but if DO is less than normal, then breathing is called oligopnea- insufficient, shallow breathing. At normal depth and frequency of breathing it is called eupnea- normal, sufficient breathing. The normal resting respiratory rate in adults is 8–20 breaths per minute; a month-old baby - about 50; one year old - 35; ten years old - 20 cycles per minute.

Inspiratory reserve volume (IR ind)- the volume of air that a person can inhale with the deepest breath taken after a calm breath. The normal PO value is 50-60% of the VC value (2-3 l).

Expiratory reserve volume (ER ext)- the volume of air that a person can exhale with the deepest exhalation made after a calm exhalation. Normally, the RO value is 20-35% of vital capacity (1-1.5 l).

Residual lung volume (RLV)- air remaining in the respiratory tract and lungs after a maximum deep exhalation. Its value is 1-1.5 l (20-30% of TEL). In old age, the value of TRL increases due to a decrease in the elastic traction of the lungs, bronchial patency, a decrease in the strength of the respiratory muscles and the mobility of the chest. At the age of 60 years, it is already about 45% of the TEL.

Functional residual capacity (FRC)- air remaining in the lungs after a quiet exhalation. This capacity consists of residual lung volume (RVV) and expiratory reserve volume (ERV).

Not all atmospheric air entering the respiratory system during inhalation takes part in gas exchange, but only that which reaches the alveoli, which have a sufficient level of blood flow in the capillaries surrounding them. In this regard, there is something called dead space.

Anatomical dead space (AMP)- this is the volume of air located in the respiratory tract to the level of the respiratory bronchioles (these bronchioles already have alveoli and gas exchange is possible). The size of the AMP is 140-260 ml and depends on the characteristics of the human constitution (when solving problems in which it is necessary to take into account the AMP, but its value is not indicated, the volume of the AMP is taken equal to 150 ml).

Physiological dead space (PDS)- the volume of air entering the respiratory tract and lungs and not participating in gas exchange. The FMP is larger than the anatomical dead space, since it includes it as an integral part. In addition to the air in the respiratory tract, the FMP includes air that enters the pulmonary alveoli, but does not exchange gases with the blood due to the absence or reduction of blood flow in these alveoli (this air is sometimes called alveolar dead space). Normally, the value of functional dead space is 20-35% of the tidal volume. An increase in this value above 35% may indicate the presence of certain diseases.

Table 1. Indicators of pulmonary ventilation

In medical practice, it is important to take into account the dead space factor when designing breathing devices (high-altitude flights, scuba diving, gas masks), and carrying out a number of diagnostic and resuscitation measures. When breathing through tubes, masks, hoses, additional dead space is connected to the human respiratory system and, despite the increase in the depth of breathing, ventilation of the alveoli with atmospheric air may become insufficient.

Minute breathing volume

Minute respiration volume (MRV)- volume of air ventilated through the lungs and respiratory tract in 1 minute. To determine the MOR, it is enough to know the depth, or tidal volume (TV), and respiratory frequency (RR):

MOD = TO * BH.

In mowing, MOD is 4-6 l/min. This indicator is often also called pulmonary ventilation (distinguished from alveolar ventilation).

Alveolar ventilation

Alveolar ventilation (AVL)- the volume of atmospheric air passing through the pulmonary alveoli in 1 minute. To calculate alveolar ventilation, you need to know the value of the AMP. If it is not determined experimentally, then for calculation the volume of AMP is taken equal to 150 ml. To calculate alveolar ventilation, you can use the formula

AVL = (DO - AMP). BH.

For example, if a person’s breathing depth is 650 ml, and the respiratory rate is 12, then AVL is equal to 6000 ml (650-150). 12.

AB = (DO - WMD) * BH = DO alv * BH

AB - alveolar ventilation;
DO alve - tidal volume of alveolar ventilation;
RR - respiratory rate

Maximum ventilation (MVL)- the maximum volume of air that can be ventilated through a person’s lungs in 1 minute. MVL can be determined by voluntary hyperventilation at rest (breathing as deeply as possible and often at a slant is permissible for no more than 15 seconds). With the help of special equipment, MVL can be determined while a person is performing intense physical work. Depending on the constitution and age of a person, the MVL norm is within the range of 40-170 l/min. In athletes, MVL can reach 200 l/min.

Flow indicators of external respiration

In addition to lung volumes and capacities, so-called flow indicators of external respiration. The simplest method for determining one of them, peak expiratory flow rate, is peak flowmetry. Peak flow meters are simple and quite affordable devices for use at home.

Peak expiratory flow rate(POS) - the maximum volumetric flow rate of exhaled air achieved during forced exhalation.

Using a pneumotachometer device, you can determine not only the peak volumetric flow rate of exhalation, but also inhalation.

In a medical hospital, pneumotachograph devices with computer processing of the received information are becoming increasingly common. Devices of this type make it possible, based on continuous recording of the volumetric velocity of the air flow created during exhalation of the forced vital capacity of the lungs, to calculate dozens of indicators of external respiration. Most often, POS and maximum (instantaneous) volumetric air flow rates at the moment of exhalation are determined as 25, 50, 75% FVC. They are called respectively indicators MOS 25, MOS 50, MOS 75. The definition of FVC 1 is also popular - the volume of forced expiration for a time equal to 1 e. Based on this indicator, the Tiffno index (indicator) is calculated - the ratio of FVC 1 to FVC expressed as a percentage. A curve is also recorded that reflects the change in the volumetric velocity of the air flow during forced exhalation (Fig. 2.4). In this case, the volumetric velocity (l/s) is displayed on the vertical axis, and the percentage of exhaled FVC is displayed on the horizontal axis.

In the graph shown (Fig. 2, upper curve), the vertex indicates the value of PVC, the projection of the moment of exhalation of 25% FVC on the curve characterizes MVC 25, the projection of 50% and 75% FVC corresponds to the values of MVC 50 and MVC 75. Not only flow velocities at individual points, but also the entire course of the curve are of diagnostic significance. Its part, corresponding to 0-25% of the exhaled FVC, reflects the air patency of the large bronchi, trachea, and the area from 50 to 85% of the FVC - the patency of the small bronchi and bronchioles. A deflection in the descending section of the lower curve in the expiratory region of 75-85% FVC indicates a decrease in the patency of the small bronchi and bronchioles.

Rice. 2. Stream breathing indicators. Note curves - the volume of a healthy person (upper), a patient with obstructive obstruction of the small bronchi (lower)

Determination of the listed volume and flow indicators is used in diagnosing the state of the external respiration system. To characterize the function of external respiration in the clinic, four variants of conclusions are used: normal, obstructive disorders, restrictive disorders, mixed disorders (a combination of obstructive and restrictive disorders).

For most flow and volume indicators of external respiration, deviations of their value from the proper (calculated) value by more than 20% are considered to be outside the norm.

Obstructive disorders- these are obstructions in the patency of the airways, leading to an increase in their aerodynamic resistance. Such disorders can develop as a result of increased tone of the smooth muscles of the lower respiratory tract, with hypertrophy or swelling of the mucous membranes (for example, with acute respiratory viral infections), accumulation of mucus, purulent discharge, in the presence of a tumor or foreign body, dysregulation of the patency of the upper respiratory tract and other cases.

The presence of obstructive changes in the airways is judged by a decrease in POS, FVC 1, MOS 25, MOS 50, MOS 75, MOS 25-75, MOS 75-85, the value of the Tiffno test index and MVL. The Tiffno test rate is normally 70-85%; a decrease to 60% is regarded as a sign of a moderate disorder, and to 40% as a severe disorder of bronchial obstruction. In addition, with obstructive disorders, indicators such as residual volume, functional residual capacity and total lung capacity increase.

Restrictive violations- this is a decrease in the expansion of the lungs when inhaling, a decrease in respiratory excursions of the lungs. These disorders can develop due to decreased compliance of the lungs, damage to the chest, the presence of adhesions, accumulation of fluid, purulent contents, blood in the pleural cavity, weakness of the respiratory muscles, impaired transmission of excitation at neuromuscular synapses and other reasons.

The presence of restrictive changes in the lungs is determined by a decrease in vital capacity (at least 20% of the proper value) and a decrease in the MVL (nonspecific indicator), as well as a decrease in lung compliance and, in some cases, an increase in the Tiffno test score (more than 85%). With restrictive disorders, total lung capacity, functional residual capacity, and residual volume are reduced.

The conclusion about mixed (obstructive and restrictive) disorders of the external respiration system is made with the simultaneous presence of changes in the above flow and volume indicators.

Lung volumes and capacities

Tidal volume - this is the volume of air that a person inhales and exhales in a calm state; in an adult it is 500 ml.

Inspiratory reserve volume- this is the maximum volume of air that a person can inhale after a quiet breath; its size is 1.5-1.8 liters.

Expiratory reserve volume - this is the maximum volume of air that a person can exhale after a quiet exhalation; this volume is 1-1.5 liters.

Residual volume - this is the volume of air that remains in the lungs after maximum exhalation; The residual volume is 1 -1.5 liters.

Rice. 3. Changes in tidal volume, pleural and alveolar pressure during lung ventilation

Vital capacity of the lungs(VC) is the maximum volume of air that a person can exhale after the deepest breath. Vital capacity includes inspiratory reserve volume, tidal volume and expiratory reserve volume. The vital capacity of the lungs is determined by a spirometer, and the method for determining it is called spirometry. Vital capacity in men is 4-5.5 l, and in women - 3-4.5 l. It is greater in a standing position than in a sitting or lying position. Physical training leads to an increase in vital capacity (Fig. 4).

Rice. 4. Spirogram of pulmonary volumes and capacities

Functional residual capacity(FRC) is the volume of air in the lungs after a quiet exhalation. FRC is the sum of expiratory reserve volume and residual volume and is equal to 2.5 liters.

Total lung capacity(OEL) - the volume of air in the lungs at the end of a full inspiration. TLC includes residual volume and vital capacity of the lungs.

Dead space is formed by air that is located in the airways and does not participate in gas exchange. When you inhale, the last portions of atmospheric air enter the dead space and, without changing its composition, leave it when you exhale. The dead space volume is about 150 ml, or approximately 1/3 of the tidal volume during quiet breathing. This means that out of 500 ml of inhaled air, only 350 ml enters the alveoli. By the end of a quiet exhalation, the alveoli contain about 2500 ml of air (FRC), so with each quiet breath, only 1/7 of the alveolar air is renewed.