Oscillometric method for measuring blood pressure. The correctness of the oscillometric method of measuring blood pressure with a tonometer from a medical point of view

Many people may not be aware of abnormalities in the functioning of the heart muscle. Often, with arrhythmia, the patient does not feel pain or discomfort, but if such a diagnosis is made, it is necessary to constantly monitor the pulse and blood pressure using a tonometer. However, only a tonometer with special functions is suitable for this purpose.

Pulse and blood pressure during arrhythmia: tonometer readings

To monitor heart function at home, check your pulse daily. By measuring it, deterioration of the condition in MA is detected. With this heart disease, the pulse has the following characteristics:

Lack of rhythm.
Pulse does not match heart rate.
Different content of the pulse wave.

Among all the characteristic features, the most indicative is considered to be a pulse deficiency, which determines hemodynamics.

Important! To improve myocardial contractility, glycoside therapy is performed.

Learning to control the condition of the heart muscle is not difficult. You need to consult with your doctor, who will explain the main points.

With MA, patients experience low blood pressure. Hypertension causes many problems and discomfort for patients. Therefore, if there is a diagnosis of atrial fibrillation, it is necessary to control blood pressure.

With self-measurement, not only the condition is determined, but also the reason that caused the decrease in blood pressure. Having learned the factors that led to a decrease in blood pressure, the patient will be able to eliminate the threat of a hypertensive crisis.

It will be great if the patient buys a tonometer with a function for detecting atrial fibrillation, because this diagnosis has practically no manifestations in the initial stages.

To raise blood pressure with medications, it is strongly recommended to check your blood pressure with a tonometer, because many rely only on symptoms of low blood pressure. With MA, it is important to measure pulse and pressure several times during the day, since this is a serious disease that requires accurate ongoing diagnosis.

Tonometers

Not all devices are capable of automatically detecting arrhythmia; in particular, oddly enough, automatic tonometers have a high probability of misdiagnosis.

A qualified specialist measures blood pressure with a sphygmomanometer, relying on auscultation. However, even a qualified physician may have difficulty recognizing Korotkoff sounds in AF because the initial attenuation occurs due to this pathology.

It is impossible to check blood pressure yourself in this way, and relatives will not be able to do this either. Based on considerations of ease of use, most tonometers are semi- or automatic.

According to manufacturers, they allow you to monitor your pulse, but not all models are able to detect MA and accurately measure blood pressure. Therefore, it is not worth buying cheap samples.

The choice of a tonometer must be approached responsibly, so even the recommendations of the attending physician must be taken into account. Below are some good models.

Omron M3 Family

This model is automatic and can simultaneously memorize the readings of two people. The shoulder cuff has a fan type and a correct position indicator, which will help you measure your blood pressure accurately. The display of the device is large, with large numbers. There is an arrhythmia indicator, but operating the device is quite difficult, which often causes difficulties for older people.

Omron M2 Basic

It is also an automatic version of the tonometer, which can be purchased at a low price. The good news is that it is easy to use, which is why many people choose this particular model. The device has no additional functions (there is no arrhythmia icon on the tonometer), but is only intended to measure blood pressure. The shoulder cuff is medium size. Can be used for daily blood pressure monitoring, but if the patient has atrial fibrillation, the results may be erroneous.

Little Doctor LD1

The semi-automatic device will accurately determine the pressure status, and it has simple controls. The cuff is filled with air using a bulb, and a special button is used to deflate the air. The result obtained is displayed on the display and recorded in the memory, which is designed for 60 measurements. To accurately determine the pressure during atrial fibrillation, there is an automatic function to find the average value of the last 3 measurements.

Tensoval duo control

This tonometer is considered professional because it can be used to correctly measure blood pressure at home, even with atrial fibrillation. After conducting clinical studies, it was found that the device has invasive measurement accuracy. A tonometer with a function for diagnosing arrhythmia, working in combination with two methods - auscultatory and oscillometric.

The video tells which tonometer is effective for atrial fibrillation, and which one is used to measure pressure without pathologies in the heart.

Rules for choosing a tonometer

Choosing a tonometer is not difficult - it may seem so to many, but finding a high-quality device with high accuracy is not so easy. To ensure that the purchased device is of high quality, pay attention to the following requirements:

If there is a display, it must be protected from moisture and dust, and the numbers must be large.
The accuracy of the measurement will depend on the fit of the cuff around the arm circumference.
Voice notification will be a great feature for visually impaired people.
Function for detecting cardiac arrhythmia. Simple blood pressure monitors are ineffective for atrial fibrillation.

Attention! Simple blood pressure monitors rely on pulse wave detection, which does not remain stable during MA.

The tonometer shows atrial fibrillation: what to do?

Low blood pressure is considered less dangerous than high blood pressure, but it is better if blood pressure is within the normal range.

To effectively raise blood pressure during MA, it is best to follow your doctor’s instructions. It is strictly forbidden to self-medicate, since an increase in pressure during MA in most cases leads to an increase in heart rate, so you need to be careful in choosing medications.

If the patient has found out for a sufficiently long time the reasons causing the decrease in blood pressure, then therapy must begin with the elimination of these causes.

Doctors do not recommend using stimulants right away. Strong coffee in large quantities, increased physical activity and various medications can be harmful. The first step is to try to eliminate the cause and take a sedative.

What is used to increase blood pressure?

If a patient complains to the attending physician about a frequent decrease in blood pressure, the doctor will prescribe appropriate therapy. In rare cases of low blood pressure, the use of drugs with strong effects is not recommended because side effects may occur.

Among the permitted sedatives for normalizing blood pressure are the following:

Aralia tincture will gently increase blood pressure. This herbal stimulant will have a general strengthening effect, toning the heart muscle.
Ginseng tincture. It has the same principle of action as Aralia tincture, but with less severity.
Caffeamine. Used to increase blood pressure. Cardiotonic effects can occur with an increase in heart rate, so caffeine is rarely prescribed for atrial fibrillation.
Korglykon is a good remedy for restoring heart rhythm in MA. Helps eliminate myocardial oxygen deficiency.
Ethmozin. Brings heart rate to a normal level and increases blood pressure, stabilizing the membranes of cardiomyocytes. It is not recommended to use this product on your own without medical supervision.

Attention! If blood pressure tends to decrease, then to normalize it you can resort to feasible physical activity.

Restoring heart rate in atrial fibrillation

When atrial fibrillation is detected, one cannot assume that it is atrial fibrillation, because other somatic pathologies could also be the cause of fibrillation.

In any case, the rhythm in atrial fibrillation needs to be stabilized. This is done through special therapy, which includes several groups of drugs:

beta blockers;
calcium ion blockers;
cardiac glycosides;
amiodarone group.

Before starting therapy to restore the heart rhythm, the patient must undergo several examinations that will reveal the general condition of not only the cardiovascular system, but also the kidneys and the endocrine system, since they also affect the functioning of the heart muscle.

Any cardiac arrhythmia poses a danger to health and life, so surgical treatment is necessary. If attacks of MA occur, the disease must be stopped. The mild stage can be easily treated with medication at home, while prolonged arrhythmia can be treated in a hospital.

The patient should understand that atrial fibrillation will not allow him to lead his previous lifestyle. You will need to constantly see a doctor, take medications, improve your diet, get proper rest and avoid stressful situations.

Why is daily blood pressure monitoring performed?

An important characterizing factor of human health is blood pressure. It is what determines well-being and quality of life. Today, everyone can purchase an electric automatic device for measuring blood pressure at home and obtain information about it at any time, but there are situations when it is necessary to measure this indicator more than once. In this case, 24-hour blood pressure monitoring (ABPM) is used.

Indications for the procedure
ECG and blood pressure Holter monitoring
24-hour blood pressure monitoring with the BiPiLAB system
Patient instruction

Today, three methods of measuring blood pressure are used in medicine: auscultatory, oscillometric and invasive. Most often, monitoring devices are used that incorporate oscillometric and auscultatory methods, which, in combination with each other, allow one to obtain a more complete picture of the disease.

Indications for the procedure

Persons who are suspected of having symptomatic hypertension.
Persons with “white coat” syndrome. We are talking about those who experience increased pressure within the walls of a medical institution when measured by a nurse.
Persons with “borderline” blood pressure readings, which were detected after repeated changes by the Korotkoff method.
Persons with increased blood pressure at work.
Persons suffering from concomitant diseases, which include heart failure, metabolic disorders, syncope, etc.
Persons with high blood pressure lability. We are talking about those whose blood pressure fluctuates too much from minimum to maximum values.
Elderly people over 60 years of age.
Persons with nocturnal hypertension.
Persons with bad heredity.
Persons with severe arterial hypertension that is difficult to treat.
Persons who need to obtain a prognosis for the further development of the disease.
Women who are pregnant.
Persons with disorders of the autonomic system.
Persons with type 1 diabetes mellitus.

It must be said that it will not be possible to obtain accurate data by independently measuring blood pressure, because diagnostics cannot be carried out at night, because for this a person needs to wake up, and this will inevitably increase blood pressure and distort the results. In addition, the performance of different devices may differ significantly from each other.

It is believed that the most accurate data can be obtained by measuring using the Korotkoff method. In this case, experts recommend using semi-automatic devices with automatic air injection. The manual pumping process may increase the pressure for a short time.

Devices that measure pressure on the wrist or finger are less accurate. In addition, it is better if they run on mains power rather than on batteries.

ECG and blood pressure Holter monitoring

Daily monitoring of blood pressure and ECG allows you to get a more complete picture of the disease, especially when there are hidden forms of heart disease that do not manifest themselves clinically, but are diagnosed on an ECG in a state of movement.

The American scientist Holter developed an instrumental diagnostic method, which is based on recording the electrical activity of the heart muscle, which occurs during life and changes depending on the presence of certain heart diseases. In this case, electrodes are installed on the patient’s chest, which read information about the operation of the main “motor” of the body and send it to a connected portable device.

In it, the data is processed programmatically and recorded in the form of electrocardiograms, which are stored in the device’s memory. With this method, they can simultaneously apply a cuff to the upper arm and thus carry out 24-hour blood pressure monitoring using the oscillometric method. In case of any ambiguities, the diagnosis can be extended up to 7 days.

This method has a lot of advantages and disadvantages over a standard ECG, which does not always allow recording myocardial ischemia and paroxysmal rhythm changes. This method of measuring blood pressure is almost the only one for those patients whose heart function worsens with minimal movement.

This research technique is indicated for those patients who complain of pressing or burning pain behind the chest and in the heart area, which may or may not radiate under the shoulder blade and arm from the side of the main “motor”. Pain in the left side of the chest, especially at night, is also a reason for the procedure.

This also applies to those who suffer from shortness of breath with a suffocating cough, suffer from lack of air, a feeling of a sinking heart, frequent dizziness, fainting and periodic failures in the functioning of the main “motor” of the body. The procedure has no contraindications, except in cases where it is technically impossible to perform, for example, in case of severe obesity, body burns, etc.

24-hour blood pressure monitoring with the BiPiLAB system

This device records the patient's systolic, diastolic, mean BP and pulse rate in an automatic, non-invasive manner. The oscillometric method will allow you to obtain accurate data on the patient’s health status in case of weak Korotkoff sounds, hypotension, and in cases where the auscultatory method did not produce results. In this case, a cuff is placed on the patient’s arm, which does not worsen the patient’s quality of life and does not make noise, which is very important for comfortable sleep.

The device connects to the computer programmatically, that is, through special software and a communication cable. It is often combined with Holter monitoring of ECG and blood pressure. Subsequently, data from both devices is processed in one program and the results are combined in a common report.

Patient instruction

To achieve good results and achieve a minimum number of erroneous measurements, the patient is instructed. He is introduced to the rules of behavior during monitoring, here they are:

While the device is operating, the arm with the cuff must be extended along the body and relaxed.
During the entire diagnostic period, it is not recommended to engage in physical labor and sports.
If the device starts measuring while moving, you need to stop, relax and only after finishing its work continue further actions.
It is not recommended to monitor the readings of the device during measurement, since anxious anticipation can distort further results.
At night, try to fall asleep without thinking about the operation of the device.
Keep a diary and, during monitoring, reflect in it your well-being and all your actions.

Korotkoff method

This method, developed by the Russian surgeon N.S. Korotkov in 1905, provides a very simple tonometer for measuring blood pressure, consisting of a mechanical pressure gauge, a cuff with a bulb and a phonendoscope. The method is based on complete compression of the brachial artery with a cuff and listening to the sounds that occur when air is slowly released from the cuff.

Advantages: recognized as the official standard for non-invasive blood pressure measurement for diagnostic purposes and for verification of automatic blood pressure meters; high resistance to hand movements.

Disadvantages: depends on the individual characteristics of the person making the measurement (good vision, hearing, coordination of the “hands-vision-hearing” system); sensitive to noise in the room, the accuracy of the location of the phonendoscope head relative to the artery; requires direct contact of the cuff and microphone head with the patient's skin; technically complex (increases the likelihood of erroneous indicators during measurement) and requires special training.

This is a method that uses electronic blood pressure monitors. It is based on recording with a tonometer air pressure pulsations that occur in the cuff as blood passes through a compressed section of the artery.

Advantages: does not depend on the individual characteristics of the person making the measurement (good vision, hearing, coordination of the “hands-vision-hearing” system); resistance to noise loads; allows you to determine blood pressure with a pronounced “auscultatory failure”, “endless tone”, weak Korotkoff sounds; allows you to take measurements without loss of accuracy through thin clothing fabric; no special training is required.

Disadvantage: when measuring, the hand must be motionless.

Mechanical (aneroid) and electronic meters are currently used to measure blood pressure. Mechanical meters based on the use of the Korotkoff method are mainly used in professional medicine, since without special training errors in indicators are allowed. Semi-automatic and automatic electronic blood pressure monitors are most suitable for home use. Their use does not require any prior training and, subject to simple guidelines, allows you to obtain accurate blood pressure data by pressing one button. Modern digital semi-automatic tonometers allow you to limit yourself to only a set of pressure (until a sound signal), further release of pressure, registration of systolic and diastolic pressure, sometimes - pulse and arrhythmia, the device carries out itself. Automatic blood pressure monitors themselves pump air into the cuff; sometimes they can produce data in digital form for transmission to a computer or other devices.

Work order

1. Sit at the table so that your hand rests on its surface while measuring blood pressure. The place where the cuff is applied should be approximately at the same height as the heart and the forearm should lie freely on the table and not move.

2. Place the cuff on your left arm first, with the tubes facing toward your palm. Wrap the cuff around your arm so that the bottom edge of the cuff is 2–3 cm from the elbow.

3. Fasten the cuff so that it fits snugly around your arm, but is not too tight.

4. Turn on the device and, when it is ready for measurement, inflate the cuff by pressing the bulb to a pressure of 30 - 40 mmHg. Art. higher than your expected systolic (upper) pressure. The pressure in the cuff is constantly displayed on the device screen.

5. When the required cuff pressure is reached, stop inflating the cuff. The pressure will begin to decrease. At the end of the measurement, pressure (systolic and diastolic) and pulse readings will appear on the screen, which must be recorded in the table. 6.1.

6. Release any remaining pressure in the cuff by pressing the pressure release valve. To re-measure, begin inflating the cuff again.

7. Blood pressure and pulse measurements must be taken three times on the left hand and three times on the right hand. The interval between measurements should be at least 15 seconds, and the difference in pressure readings on the hands can be significant.

8. Then, in accordance with the rules for processing the results of direct measurements, find the average values of upper and lower pressure, pulse and absolute confidence error Δ R according to the algorithm of direct multiple measurements according to the formula:

9. Record the results. Compare your data with the table data and analyze the result. Diagnose yourself.

Table 6.1.

measurement number	Pv, mm. Hg Art.	Pn, mm. Hg Art.	N

Control questions

1. In what units is blood pressure measured and why in such units? Are these units of measurement consistent with the SI system?

2. What does systolic and diastolic blood pressure indicate?

3. What danger does high and low blood pressure pose to the body?

4. What is the main role of blood circulation?

5. What methods of measuring blood pressure are there? What are their disadvantages and advantages?

6. Does atmospheric pressure affect blood pressure?

High blood pressure is one of the most common diseases in the world. Long-term arterial hypertension inevitably leads to arteriosclerosis, resulting in a risk of myocardial infarction or cerebral stroke. These so-called "vascular accidents" have unfortunately become commonplace in modern society.

Brain stroke affects approximately 420,000 patients each year in the United States, 100,000 in the UK, and 125,000 in Germany. About 50% of patients who have had a stroke become unable to work.

45% of deaths in Western countries are caused by cerebral strokes and myocardial infarction.

It is necessary to control cholesterol levels in the blood, stop smoking, and avoid prolonged increases in blood pressure. After all, high blood pressure is a very common phenomenon.

20% of the population in developed countries suffers from hypertension, which is approximately 56 million people in the United States, 13 million people in the UK and about 16 million in Germany.

Modern medicine, fortunately, offers a wide range of therapeutic measures, including diet, physical activity, and medication. However, any type of therapy requires, first of all, a correct diagnosis of blood pressure.

The diagnosis can be made in a doctor's office. However, in many cases this is not feasible. First, the results of the doctor's measurements are distorted by the so-called "white coat effect", which leads to an artificial increase in the patient's blood pressure. Second, it is difficult for working patients to visit their physicians frequently.

To assess blood pressure status on a daily basis, the patient must provide his or her own measurements to the physician. Blood pressure readings can be taken using a blood pressure monitor at patients' workplaces and/or at home. These readings should be recorded and provided to doctors during treatment.

There are currently two methods for measuring blood pressure. Patients can use automatic (electronic) blood pressure monitors, which are based on the so-called “oscillometer” method, or choose devices based on the “auscultatory” method (mechanical tonometers) for measuring blood pressure.

The auscultatory method, known as the Korotkoff/Riva-Rossi method, is based on complete clamping of the brachial artery with a cuff and listening to the sounds that occur as air is slowly released from the cuff.

Most auscultatory tonometers– manual. This means that the patient must use a stethoscope to identify the pulse tones and determine the systolic and diastolic pressure readings from the audio signals.

This method, however, can only be used properly by patients who do not have hearing or vision loss. Unfortunately, many patients suffering from arterial hypertension are elderly people susceptible to age-related hearing loss. This prevents them from using the auscultatory method.

This method also requires skills in interpreting the audio signal, so patients without special training and experience also cannot use mechanical tonometers to measure blood pressure.

Today, there are still several models of automatic tonometers on the market that use the auscultatory method of measuring blood pressure. Such tonometers turned out to be too sensitive to artificial interference and artifacts, since the microphone used in them picks up a large amount of extraneous noise.

About 10 years ago, oscillometric blood pressure measurement technology was introduced to the home blood pressure monitor market. This technology is also based on the application of a cuff to the limb. Use at home tonometers for measuring blood pressure at the upper arm or for measuring blood pressure at the wrist. Tonometers that measure arterial pressure on the upper arm provide more accurate measurement results.

The oscillometric method is based on recording with a tonometer air pressure pulsations that occur in the cuff as blood passes through a compressed section of the artery.

The main advantages of the oscillometric method are that the accuracy of the results does not depend on the hearing and vision of the person making the measurement; such tonometers are resistant to extraneous noise, allow blood pressure to be determined with weak Korotkoff sounds, and allow blood pressure to be accurately measured through thin clothing. To measure blood pressure with this tonometer, no special training is required.

Only a few specific conditions must be met: measurements must be taken at rest, you cannot move or talk during the measurement, and the cuff must be at heart level.

Today, patients are offered a wide range of tonometers for measuring blood pressure using the oscillometric method. These blood pressure monitors are quite accurate.
However, there are some points due to the structural and design features of such tonometers that still affect the accuracy of the readings. Manufacturers pay special attention to this:

reducing the influence of random movements;
the ability to accurately measure blood pressure during arrhythmia;
measuring blood pressure in patients with low pulse blood supply;
measuring the blood pressure of patients with very low or very high blood pressure.

Typically, the patient measuring blood pressure is not completely at rest. Thus, pressure readings obtained from repeated measurements differ from each other. This is not due to the inaccuracy of the blood pressure monitor, but due to the physiological variability of a person's blood pressure.

Because patients' blood pressure can change dynamically, single measurements should not be taken. To determine the actual blood pressure value, it is recommended to perform a series of repeated measurements.

It is very important that patients undergoing antihypertensive therapy record their self-reported blood pressure readings and provide them to their prescribers. These results are extremely necessary for monitoring and adjusting therapeutic prescriptions.

Summary

The oscillometric method of measuring pressure is quite reliable for assessing the level blood pressure patients suffering hypotension or hypertension.

When using this technology, there are no technological or physiological restrictions that cause significant damage to the medical value of the results obtained.

Klaus Forstner. Therapist, doctor of medicine, certified engineer.
Institute for Clinical Research of Medical Technology.
Germany, Tamm, May 16, 2002

Capacitive vessels

Capacitive vessels are mainly veins. Due to their high extensibility, they are able to accommodate or eject large volumes of blood.

In a closed vascular system, changes in the capacity of any department are necessarily accompanied by a redistribution of blood volume. Therefore, changes in the capacity of the veins that occur during contraction of smooth muscles affect the distribution of blood throughout the entire circulatory system and thereby the general parameters of blood circulation.

Some veins, mainly superficial veins, have an oval lumen at low intravascular pressure, and therefore they can accommodate some additional volume of blood without stretching, but only acquiring a more cylindrical shape.

The veins of the liver, large veins of the celiac region and the veins of the subpapillary plexus of the skin are especially capacious as a blood depot. The total volume of these veins may increase by 1 liter compared to the minimum. Short-term deposition or release of large quantities of blood can be carried out by the pulmonary veins, which are connected to the systemic circulation in parallel. This changes the venous return to the right heart and/or the output of the left heart.

Capacitance vessels regulate the filling (“priming”) of the heart pump, and therefore cardiac output. They dampen sudden changes in the volume of blood sent to the vena cava, for example, during orthoclinostatic movements of a person, carry out temporary (by reducing the speed of blood flow in the capacitive vessels of the region) or long-term (spleen sinusoids) blood deposition, regulate the linear speed of organ blood flow and blood pressure in the capillaries microregions, i.e. influence the processes of diffusion and filtration.

Blood flow - The constant movement of blood through the vessels of the circulatory system. The driving force of blood flow is the difference in blood pressure between the proximal and distal parts of the vascular bed. Blood pressure is created by the pressure of the heart and depends on the elastic properties of blood vessels. Linear blood flow velocity

in the veins, as in other parts of the vascular bed, depends on the total cross-sectional area, therefore it is smallest in venules (0.3-1.0 cm/s), largest in the vena cava (10-25 cm/s). The flow of blood in the veins is laminar, but at the point where two veins flow into one, vortex flows arise that mix the blood, its composition becomes homogeneous.

4SPHIGMOGRAPHY is a method for studying hemodynamics and diagnosing some forms of pathology of the cardiovascular system, based on graphical recording of pulse oscillations of the wall of a blood vessel. Sphygmography is carried out using special attachments to an electrocardiograph or other recorder, which make it possible to convert mechanical vibrations of the vessel wall perceived by the pulse receiver (or accompanying changes in the electrical capacitance or optical properties of the body area under study) into electrical signals, which, after preliminary amplification, are fed to the recording device. To determine the speed of propagation of the pulse wave, two sphygmograms (pulse curves) are simultaneously recorded: one pulse sensor is installed above the proximal and the other above the distal parts of the vessel. Since it takes time for the wave to propagate along the area of the vessel between the sensors, it is calculated by the delay of the wave of the distal area of the vessel relative to the wave of the proximal one. By determining the distance between the two sensors, the speed of propagation of the pulse wave can be calculated.

5 Blood pressure is the pressure of blood in the large arteries of a person. There are two indicators of blood pressure:

Systolic (upper) blood pressure is the level of blood pressure at the moment of maximum contraction of the heart.
Diastolic (lower) blood pressure is the level of blood pressure at the moment of maximum relaxation of the heart.

§ Mean arterial pressure should not be understood as the arithmetic mean between the maximum and minimum pressure.

§ If we take the average of all variable pressure values on the central pulse curve, then this will be the value of the average dynamic pressure. Normally, the average pressure is 80-90 mmHg. Art.

pulse pressure- indicator of hemodynamic status: the difference between systolic and diastolic blood pressure

Oscillometric method

This is a method that uses electronic blood pressure monitors. It is based on registration tonometer pulsations of air pressure that occur in the cuff as blood passes through a compressed section of the artery.

Technique for determining blood pressure in the brachial artery using the oscillometric method:

This method consists of observing the oscillations of the needle of a spring pressure gauge. Here, air is also pumped into the cuff until the brachial artery is completely compressed. Then the air begins to be gradually released, opening the valve, and the first portions of blood, entering the artery, give oscillations, i.e. oscillations of the arrow, indicating systolic blood pressure. The oscillations of the pressure gauge needle first intensify and then suddenly decrease, which corresponds to the minimum pressure. Spring pressure gauges are quite convenient for transportation, but, unfortunately, the springs soon weaken, do not give accurate vibrations and quickly fail.

Korotkoff method

This method, developed by the Russian surgeon N.S. Korotkov in 1905, provides for measuring blood pressure a very simple tonometer consisting of mechanical pressure gauge, bulb cuff and phonendoscope. The method is based on complete compression of the brachial artery with a cuff and listening to the sounds that occur when air is slowly released from the cuff.

Technique for determining blood pressure in the brachial artery using the Korotkov method:

A cuff is loosely placed on the bare shoulder of the patient’s left arm, 2-3 cm above the elbow, and secured so that only one finger passes between it and the skin. The subject's hand is positioned comfortably, palm up. The brachial artery is found in the elbow bend and a phonendoscope is applied to it tightly, but without pressure. Then the balloon is gradually pumped with air, which flows simultaneously into both the cuff and the pressure gauge. Under pressure air, mercury in the manometer rises into the glass tube. The numbers on the scale will show the level pressure air in the cuff, i.e. the force with which the artery in which the measurement is being measured is compressed through the soft tissue pressure. When injecting air, care is required, since under strong pressure the mercury can be thrown out of the tube. Gradually pumping air into the cuff, record the moment when the sounds of pulse beats disappear. Then they begin to gradually reduce pressure in the cuff, slightly opening the valve at the cylinder. At the moment when the back pressure in the cuff reaches the systolic value pressure, a short and rather loud sound is heard - a tone. The numbers at the level of the mercury column at this moment indicate the systolic pressure. With a further drop in pressure in the cuff, the sounds weaken and gradually disappear. At the moment the tones disappear pressure in the cuff corresponds diastolic pressure.

Indirect blood pressure measurement (auscultatory method), if performed correctly, is safe, relatively painless and provides reliable information. The diagnosis of hypertension in children and adolescents is based solely on the accuracy of blood pressure measurements using this method.

Equipment

Blood pressure is usually measured using a sphygmomanometer (mercury or aneroid) and a phonendoscope (stethoscope). The scale divisions of a sphygmomanometer (mercury or aneroid) should be 2 mm Hg. The readings of a mercury manometer are estimated at the upper edge (meniscus) of the mercury column. A mercury manometer is considered the "gold standard" among all devices used to measure blood pressure, as it is the most accurate and reliable tool. Mercury pressure gauges should be checked once a year. An aneroid pressure gauge consists of metal bellows that expand as the air pressure in the cuff increases, and the pressure value is estimated by the mark on the scale, which is indicated by the pressure gauge needle. If the aneroid sphygmomanometer readings differ from the mercury manometer by ≥ 3 mm, then it must be calibrated.

A phonendoscope (stethoscope) must have an attachment with a bell or membrane for listening to low-frequency sounds. The phonendoscope (stethoscope) headphones must fit the examiner's external ear canal and block external noise.

7
Internal energy can change only under the influence of external influences, that is, as a result of imparting an amount of heat to the system Q and doing work on it ( - A ):

. (11)

The basis for measuring the energy consumed by the human body and the energy of food consumed is the same unit of measurement - the joule or calorie. This made it possible to solve the important problem of establishing the correspondence of human nutrition to the energy costs it produces.

A diet in which the calorie content of the daily diet does not cover the energy expenditure produced during the day causes the occurrence of a negative energy balance. The latter is characterized by the mobilization of all the body's resources for maximum energy production to cover the resulting energy deficit as much as possible.

In this case, all nutrients, including protein, are used as a source of energy. The predominant consumption of protein for energy purposes to the detriment of its direct plastic purpose can be considered as the main unfavorable factor of negative energy balance. At the same time, not only the protein supplied in food is consumed for energy purposes, but also tissue protein, which, with a long-term negative energy balance, begins to be widely used for energy needs, causing the occurrence of protein deficiency in the body.

No less serious negative consequences are characterized by a pronounced positive energy balance, when for a long time the energy value of the diet significantly exceeds the energy expenditure produced. Excess body weight, obesity, atherosclerosis, and hypertension largely progress and develop on the basis of a long-term positive energy balance.

Thus, both negative and pronounced positive energy balance adversely affects the physical state of the body, leading to significant metabolic disorders, functional and morphological changes in various body systems.

Physiologically normal conditions are created when energy balance is ensured, i.e. when a more or less close correspondence between energy intake and expenditure during the day is achieved.

82law of thermodynamics - The process in which work is converted into heat without any other changes in the system is irreversible, that is, it is impossible to convert all the heat taken from a source with a uniform temperature into work without making other changes in the system. The temperature threshold for human tissue functioning is approximately 45 °C. The higher the temperature of the external source, the less time is needed for the interstitial temperature to rise above the threshold of vital activity. The temperature threshold for the vital activity of human tissues and the degree of skin damage, depending on the type of thermal agent, its heat capacity and the duration of the high temperature. The effect of electric current on the body and cold damage.

9The relative role of heat transfer components is different for different

animals. Based on the fundamental features of heat transfer, two types are distinguished:

large ecological groups of animals: poikilothermic and homeothermic

A characteristic feature of the heat exchange of poikilo-thermal animals is that, due to the relatively low level of metabolism, the main source of thermal energy in animals is

them is external heat. It is this circumstance that explains the direct dependence of the body temperature of poikilothermic animals on the temperature of the environment, more precisely on the influx of heat from the outside, since terrestrial poikilothermic animals also use radiation heating.

Strictly speaking, complete correspondence of body temperature to temperature

environment is observed quite rarely. In most cases, there is a certain discrepancy between these indicators, and in the range of low and moderate environmental temperatures, the body temperature of animals turns out to be slightly higher, and in very hot conditions – lower. The reason is that even with a low level of metabolism, the body always produces

generates some amount of heat; It is this endogenous heat that causes an increase in body temperature.

P fundamental The difference between the heat exchange of homeothermal animals and the heat exchange of poikilothermic animals is that adaptations to environmental temperature conditions developed not along the lines of passive resistance to temperature influences, but in the direction of maintaining thermal homeostasis of the “internal environment” with the active participation of regulatory systems at the level the whole organism. Thus, homeothermy is a form

heat exchange, in which, due to maintaining the relative constancy of the “internal environment” of the body, biochemical and physiological processes always occur under optimal temperature conditions.

The homeothermic type of heat exchange is determined primarily by a high level of metabolism. The metabolic rate of birds and mammals is one to two orders of magnitude higher than that of poikilothermic animals at optimal environmental temperatures.

A high level of metabolism leads to the fact that in homeothermic

Animals' heat balance is based on the use of their own heat production. For this reason, birds and mammals are classified as endothermic animals, in contrast to ectothermic animals, which include all other (poikilothermic) animals. Endothermy is an important property: it leads to a significant reduction in the dependence of energy exchange between birds and mammals.

powered by ambient temperature. An equally important feature of homeothermic animals is the perfect development of the body’s regulatory systems and, first of all, the central nervous system. This opens up the possibility of fine regulation of the processes of heat production and heat transfer in accordance with environmental conditions and functional state

body.

Isothermia - constancy of body temperature

10CHEMICAL THERMOREGULATION

regulation mechanism heat generation, which consists in maintaining heat balance, or homeostasis, by changing heat production due to changes in metabolic rate. From an energetic point of view, this method of maintaining temperature homeostasis compared to physical thermoregulation quite wasteful. An increase in heat production by increasing metabolic intensity requires compensation through a corresponding influx of energy from the outside (i.e., increased nutrition). For example, if in a severe winter cold an animal is unable to obtain a sufficient amount of food in a short day, then a huge disproportion will arise between the loss of thermal energy and its replenishment. In harsh winters, you can often see the corpses of starved (due to the depletion of internal fat reserves) and frozen birds.

Physical thermoregulation is the regulation of heat transfer. Its mechanisms ensure that body temperature is maintained at a constant level both in conditions where the body is in danger of overheating and when cooling.

Physical thermoregulation is carried out by changes in heat transfer by the body. It acquires particular importance in maintaining a constant body temperature while the body is in conditions of elevated ambient temperature.

Heat transfer is carried out by heat radiation (radiation heat transfer), convection, i.e. movement and mixing of air heated by the body, heat conduction, i.e. heat transfer from a substance in contact with the surface of the body. The nature of heat loss from the body changes depending on the metabolic rate.

11 dosimetry - a set of measurement and (or) calculation methods doses ionizing radiation, based on the quantitative determination of changes produced in matter by radiation (radiation effects). There are direct (absolute) calorimetric. D.'s method, based on the direct measurement of radiation energy absorbed in the form of heat released in the working fluid of the calorimeter, and indirect (relative) methods, in which radiation is measured. effects proportional to the absorbed dose.

Absorbed dose

fundamental dosimetric quantity.; absorbed radiation energy per unit mass of a substance. It is measured in joules divided by kilogram (J(kg-1) and has a special name - gray (Gy). The previously used non-system unit rad is equal to 0.01 Gy.

Relative biological efficiency coefficient

(syn. coefficientOBE)

a value showing how many times the biological effect of ionizing radiation of a given type is greater or less than the effect of standard radiation; represents the ratio of absorbed doses of a given and standard radiation that cause the same biological effect.

Equivalent dose is the product of the absorbed dose of radiation in a biological tissue and the quality factor of this radiation in a given biological tissue. The SI unit of equivalent dose is the sievert (Sv). 13в = J/kg, i.e. A sievert is equal to the equivalent dose at which the product of the absorbed dose in biological tissue of standard composition and the average quality factor is 1 J/kg. Derived units are also used: mSv – millisievert (a thousand times less than Sv); µSv – microsievert (a million times less than Sv).

12UHF therapy- a method of physiotherapy, which is based on the effect on the patient’s body of a high-frequency magnetic field with a wavelength of 1-10 meters. During the interaction of the magnetic field emitted by the physiotherapeutic device and the patient’s body, an ultra-high frequency magnetic field is formed. In this case, the patient feels the thermal effects of the influence of this magnetic field on him. The standard frequency of electromagnetic oscillations for this therapy technique is 40.68 MHz.

This technique is widely used in physiotherapy. The basis of its effect is the improvement of microcirculation at the site of exposure to the magnetic field. As a result, repair and regeneration processes are accelerated and inflammation is reduced. Also, an alternating magnetic field reduces the sensitivity of nerve endings receptors, which leads to a decrease in the intensity of pain.

Indications [edit]

Acute inflammatory processes of the skin and subcutaneous tissue (especially purulent).

Inflammatory diseases of the musculoskeletal system.

Inflammatory diseases of the ENT organs.

Inflammatory lung diseases.

Gynecological diseases of an inflammatory nature.

Diseases of the peripheral nervous system.

Inflammatory diseases of the gastrointestinal tract

13Amplipulse therapy

Amplipulse therapy is a therapeutic technique in which areas of the body are exposed to sinusoidal simulated currents (SMC). They represent currents of alternating direction with a frequency from 2 to 5 kHz, modulated in amplitude from 10 to 150 Hz. SMTs are widely used in various fields of medicine, including cosmetology. They easily pass through the skin, penetrate deeply into tissues, and stimulate nerve endings and muscle fibers.

Due to its analgesic, anti-inflammatory, absorbable, decongestant, vasodilator, hypotensive and other effects of sinusoidal currents, amplipulse therapy is used to treat the following ailments:

diseases of the nervous system;
vegetative-vascular and trophic disorders;
diseases of the gastrointestinal tract, respiratory organs, joints, genitourinary system;
diabetes mellitus, etc.

During the procedure, special electrodes are placed and fixed in the problem area. Depending on the disease and individual characteristics, the doctor determines the size of the electrodes, their mode, modulation frequency, duration of sendings, intensity of exposure, number of procedures and their frequency. Typically, the course of treatment ranges from 8 to 15 sessions, several times a week, sometimes even 2 times a day.

14Darsonvalization- physiotherapeutic effects on the surface tissues and mucous membranes of the body with high-frequency pulsed currents. The method is named after its author, French physiologist and physicist Arsène d’Arsonval. Darsonvalization is used to treat disorders in superficial tissues and mucous membranes, as well as hair. In addition, darsonvalization is used for cosmetic procedures. Currently, Darsonvalization is successfully used in dermatology, cosmetology, surgery, urology, gynecology, neuropathology, treatment of diseases of internal organs, etc.

Thanks to the use of the Darsonval apparatus, blood circulation improves, biochemical metabolic processes in the skin and under it are activated, tissue nutrition and oxygen supply are enhanced, and the sensitivity threshold of pain receptors to external irritations is lowered, which provides an analgesic effect.

With regular use of the Darsonval apparatus, the activity of the central nervous system improves, in particular sleep and performance; vascular tone is normalized; headaches and fatigue go away; the body's immunity increases.

The main operating factors of the Darsonval apparatus are high-frequency current, high-voltage corona discharge, heat generated in the tissues of the body and in the area of the corona discharge, a small amount of ozone and nitrogen oxides, weak ultraviolet radiation generated by the corona discharge, weak mechanical vibrations of the supra-tonal frequency in the tissues (oscillatory effect ).

The oscillometric method of measuring blood pressure is widely used nowadays. In medicine, two more types of blood pressure measurement are used - invasive and non-invasive.

Measurement methods

All methods of measuring pressure that exist today were finally developed in the 20th century.

The invasive method, also called the direct method, involves inserting a special probe into a person’s artery, onto which a pressure sensor is installed. From it, readings are transmitted to a special device, which processes the data and displays arterial blood pressure values on the monitor in real time. The advantage of the method is the high accuracy of measurements, which does not depend on the condition of the blood vessels, the presence of arrhythmia and other pathologies of the human body. But measuring blood pressure in vessels in this way is only possible in a hospital setting, since the patient requires constant monitoring. If the probe falls out of the artery, there will be severe bleeding and possible infection. This technique is used during surgical interventions, in intensive care and intensive care wards.

In 1905, the outstanding Russian surgeon Nikolai Sergeevich Korotkov, with a report at the Imperial Military Academy, revolutionized the practice of measuring blood pressure, proposing a new, completely non-traumatic technique, which was called the Korotkoff tone method.

Non-invasive method

The sound (auscultatory, Korotkoff sound method) method is extremely simple: a sphygmomanometer connected to a cuff and a bulb is used. At the same time, air was pumped into the cuff and the phonendoscope.
He puts a cuff on the shoulder, air is pumped into it, and the arteries are pinched. The phonendoscope is applied to the bend of the radial artery. The air from the cuff is slowly released. As soon as the first sample of blood in the artery is heard in the phonendoscope, the systolic pressure value is visually recorded on the sphygmomanometer; as soon as the sounds fade, the diastolic pressure is recorded.
This method is officially recognized by the World Health Organization as a reference method. Despite its simplicity, this technique has disadvantages:

dependence on the characteristics of the person conducting the measurement (vision and hearing);
Special skills required;
dependence on external noise.

The device for measuring blood pressure is called a tonometer.

With the development of electronics, the Omron Corporation developed the oscillometric method for measuring pressure in 1976. This is the next stage in the development of the Korotkoff tone method, only fully automated. Its essence lies in the fact that air is released from the cuff in stages, where at each stage the pulsation in the cuff is analyzed. The most powerful pulsation is systolic pressure, the attenuation is diastolic. This method is used in most automatic and semi-automatic devices for measuring blood pressure. The range of manufactured devices is extremely wide.

Simplicity and precision

Now anyone can take measurements at home without contacting a specialist. Thus, the oscillometric method is completely automated and does not depend on the user’s skills. For simplicity, we will use the term electronic tonometer.

There is a huge range of tonometers on the market: from miniature models that measure pressure on the wrist to large stationary devices for mass measurements.

Wrist blood pressure monitors are suitable for those under 30 years of age; they are less accurate. They are more suitable for those who lead an active and healthy lifestyle, play sports and serve to monitor blood pressure before and after training, adjusting the load accordingly.

Blood pressure monitors with a shoulder cuff are suitable for absolutely everyone. They come in 2 types:

semi-automatic - air is pumped into the cuff manually using a bulb, then the process is automated;
automatic - just put on the cuff and press the button.

Engineers are developing models suitable for almost all categories of citizens. There are tonometers that reliably determine blood pressure in the presence of various pathologies.

The cost of such devices is higher.

Advantages of these devices:
Anyone can use the device;
suitable for those who have arrhythmia;
low dependence on external noise;

independence from the human factor.

Myths about electronics

The pressure must be measured at rest: if you are worried or come from somewhere, you need 20 minutes. relax.

1. Measurements are taken in a sitting position, the cuff should be at heart level. When using tonometers that measure pressure at the wrist, the hand with the tonometer should be in the area of the heart.

The interval between measurements should not be less than 20 minutes. Or you need to take 3 consecutive measurements with an interval of no more than 15 seconds. and calculate the average value, discarding obviously false ones.
It is advisable to measure pressure either on a bare arm or through thin clothing.

Find out your risk level for heart attack or stroke

The oscillometric method is one of the successfully used non-invasive methods for measuring blood pressure. It is mainly used in semi-automatic and automatic devices for measuring pressure - tonometers, as well as devices for long-term recording of indicators - blood pressure monitors.

It was first proposed by the French physiologist Marey in 1876, but for a long time the method was not in demand due to the complexity of performing the study.

Now this technique has been very well studied; the obtained indicators are analyzed using special programs and converted into numbers that we see on the monitor. Manufacturers keep these programs secret and constantly improve them, trying to get rid of the main drawback that the oscillometric method has - the dependence of the accuracy of the readings on the patient’s movement during the measurement.

Principle of the method

Arterial oscillography records changes in tissue volume under conditions of dosed compression and decompression of a blood vessel. This change in volume is associated with an increase in arterial blood supply to the tissue during the pulse impulse. Compression and decompression of the limb in which the artery passes is carried out using a cuff.

In this case, the inner surface of the cuff becomes the sensor that registers changes in the volume of the limb, imperceptible to the eye. The change in pressure in the cuff is the main indicator that this method analyzes. Through the cable, the information is transmitted to the device, which processes it using an analog-to-digital converter and a microprocessor with a program for calculating indicators and turns it into an image - pressure numbers on the display.

If the rhythm is disturbed, the pulse fluctuations become irregular, which is also detected by the sensitive cuff. Information about a missed or premature heartbeat is perceived and reflected on the display as an arrhythmia.

It is clear that oscillography also records the pulse, the measurement results of which are also visible on the tonometer screen.

How is the measurement carried out?

The blood pressure cuff is designed in such a way that air can be injected into it in measured doses and then released. In the first phase, compression (compression) of the limb occurs, and in the second phase, relaxation (decompression) occurs. The oscillometric method assumes that it simultaneously serves as a receiver of pulse oscillations (unlike the Korotkov method).

The cuff is placed and fixed on the shoulder. The compression in it, using an automatic or manual pump, is raised to a level slightly higher than the systolic pressure in the brachial artery. In automatic blood pressure monitors, the required compression in the cuff is determined automatically. In semi-automatic devices, the patient himself orients himself to the desired degree of compression of the limb. After this, a smooth stepwise decrease in pressure in the cuff is performed - decompression.

In the very first arterial oscilloscopes, all measurements were made on paper tape. During decompression, when the pressure in the cuff became equal to systolic, an abrupt increase in oscillations, that is, deviations of the recording from a straight line, appeared on the arterial oscillogram. Oscillations stopped at the moment when the level of compression in the cuff became equal to diastolic. The cuff stopped detecting changes in shoulder volume during pulse waves.

The blood pressure measurement method used in modern machines is based on the same principle. At each stage of decompression, the device determines how pronounced the vibrations inside the cuff are. When these fluctuations sharply increase, systolic pressure is recorded, and when they stop, diastolic pressure is recorded.

The method determines the pressure, which is usually slightly higher than when using Korotkoff sounds, listened to with a phonendoscope. However, these indicators differ slightly, and in arterial hypertension they are almost equal.

Advantages and disadvantages

The main disadvantage of the oscillometric method is the need for immobility of the limb during measurement.

The method also has advantages over measuring blood pressure using Korotkoff sounds:

the accuracy of the results does not depend on the person conducting the research;
the ability to correctly measure with weak tones, an “endless” tone or an “auscultatory failure”, when the usual sound characteristics are changed using a phonendoscope;
the ability to apply the cuff to a thin layer of clothing;
unnecessary special training.

The oscillometry method is also used in devices for analyzing arterial and peripheral vascular resistance, stroke and cardiac output and other characteristics of blood circulation.

The oscillometric method of measuring blood pressure is widely used nowadays. In medicine, two more types of blood pressure measurement are used - invasive and non-invasive.

Measurement methods

All methods of measuring pressure that exist today were finally developed in the 20th century.

Non-invasive method

dependence on the characteristics of the person conducting the measurement (vision and hearing);
Special skills required;
dependence on external noise.

The device for measuring blood pressure is called a tonometer.

Simplicity and precision

There is a huge range of tonometers on the market: from miniature models that measure pressure on the wrist to large stationary devices for mass measurements.

Blood pressure monitors with a shoulder cuff are suitable for absolutely everyone. They come in 2 types:

semi-automatic - air is pumped into the cuff manually using a bulb, then the process is automated;
automatic - just put on the cuff and press the button.

Engineers are developing models suitable for almost all categories of citizens. There are tonometers that reliably determine blood pressure in the presence of various pathologies.

The cost of such devices is higher.

Advantages of these devices:
Anyone can use the device;
suitable for those who have arrhythmia;
low dependence on external noise;

independence from the human factor.

Myths about electronics

The pressure must be measured at rest: if you are worried or come from somewhere, you need 20 minutes. relax.

1. Measurements are taken in a sitting position, the cuff should be at heart level. When using tonometers that measure pressure at the wrist, the hand with the tonometer should be in the area of the heart.

The interval between measurements should not be less than 20 minutes. Or you need to take 3 consecutive measurements with an interval of no more than 15 seconds. and calculate the average value, discarding obviously false ones.
It is advisable to measure pressure either on a bare arm or through thin clothing.

Find out your risk level for heart attack or stroke

Take a free online test from experienced cardiologists

Brain stroke affects approximately 420,000 patients each year in the United States, 100,000 in the UK, and 125,000 in Germany. About 50% of patients who have had a stroke become unable to work.

45% of deaths in Western countries are caused by cerebral strokes and myocardial infarction.

It is necessary to control cholesterol levels in the blood, stop smoking, and avoid prolonged increases in blood pressure. After all, high blood pressure is a very common phenomenon.

20% of the population in developed countries suffers from hypertension, which is approximately 56 million people in the United States, 13 million people in the UK and about 16 million in Germany.

There are currently two methods for measuring blood pressure. Patients can use automatic (electronic) tonometers, which are based on the so-called “oscillometer” method, or choose devices based on the “auscultatory” method (mechanical tonometers) for measuring blood pressure.

This method also requires skills in interpreting the audio signal, so patients without special training and experience also cannot use mechanical tonometers to measure blood pressure.

Today on the market there are still several models of automatic tonometers that use the auscultatory method of measuring blood pressure. Such tonometers turned out to be too sensitive to artificial interference and artifacts, since the microphone used in them picks up a large amount of extraneous noise.

The oscillometric method is based on recording with a tonometer air pressure pulsations that occur in the cuff as blood passes through a compressed section of the artery.

Only a few specific conditions must be met: measurements must be taken at rest, you cannot move or talk during the measurement, and the cuff must be at heart level.

reducing the influence of random movements;
the ability to accurately measure blood pressure during arrhythmia;
measuring blood pressure in patients with low pulse blood supply;
measuring the blood pressure of patients with very low or very high blood pressure.

Summary

The oscillometric method of measuring pressure is quite reliable for assessing the level blood pressure patients suffering hypotension or hypertension.

When using this technology, there are no technological or physiological restrictions that cause significant damage to the medical value of the results obtained.

Klaus Forstner. Therapist, doctor of medicine, certified engineer.
Institute for Clinical Research of Medical Technology.
Germany, Tamm, May 16, 2002

Capacitive vessels

Capacitive vessels are mainly veins. Due to their high extensibility, they are able to accommodate or eject large volumes of blood.

5 Blood pressure is the pressure of blood in the large arteries of a person. There are two indicators of blood pressure:

Systolic (upper) blood pressure is the level of blood pressure at the moment of maximum contraction of the heart.
Diastolic (lower) blood pressure is the level of blood pressure at the moment of maximum relaxation of the heart.

§ Mean arterial pressure should not be understood as the arithmetic mean between the maximum and minimum pressure.

§ If we take the average of all variable pressure values on the central pulse curve, then this will be the value of the average dynamic pressure. Normally, the average pressure is 80-90 mmHg. Art.

pulse pressure- indicator of hemodynamic status: the difference between systolic and diastolic blood pressure

Oscillometric method

Technique for determining blood pressure in the brachial artery using the oscillometric method:

Korotkoff method

Technique for determining blood pressure in the brachial artery using the Korotkov method:

Equipment

7
Internal energy can change only under the influence of external influences, that is, as a result of imparting an amount of heat to the system Q and doing work on it ( - A ):

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