Direct method for measuring hell. Pressure measurement. Avoid Common Mistakes When Measuring Blood Pressure

Measuring blood pressure with the help of modern devices does not present any difficulties. Any average person can master the indirect method according to the Korotkov method.

The pressure of blood on the walls of blood vessels is called blood or arterial pressure. This is one of the important indicators of the health of the body, which is determined when examining a patient. Methods for measuring blood pressure are divided into direct and indirect. From the name, the method of measuring blood pressure becomes clear: directly in the vessel or by indirect signs of the passage of blood in the vessels.

Probably, any person will say that the pressure indicator in the vessels of the body is characterized by two numbers. What do they mean? The heart ejects blood with effort from the left ventricle, forcing it to move through the systemic circulation. The contractile movement of the heart muscle is called systole. Accordingly, the pressure that is measured in the vessels at this moment is called systolic.

The moment of relaxation of the myocardium is called "diastole", therefore, the second figure characterizing the level of blood pressure is called diastolic. The gap in the digital values determines, its value also plays an important role in the well-being of the patient.

Since ancient times, doctors have been looking for ways to measure blood pressure, since even then it was clear that the movement of blood plays an important role in stabilizing the patient's condition. Not in vain, several centuries ago, almost all diseases were treated with bloodletting, while noting the positive impact of such procedures on health.

The use of a special apparatus for measuring blood pressure began at the beginning of the last century. This was done with instruments named after the author Riva Rotchi. They used the same principle as today when measuring blood pressure using the Korotkoff method.

Systolic pressure levels of 110-129 mm Hg are considered normal. Art., diastolic - 70 - 99 mm Hg. Art.

All values that differ from these values in one direction or another should be considered as not corresponding to normal and requiring correction with the help of medications, auxiliary measures or a set of measures. Each individual case must be analyzed separately, and this should be done by a doctor. It is strictly forbidden to self-medicate, use the means of therapy on your own.

Ways

Since pressure is a very important indicator not only in everyday life, but in critical situations, it can be measured in several ways. There are the following methods for measuring blood pressure:

In a direct way, you can measure the blood pressure in the artery directly in the bloodstream. To do this, you need to connect the measuring device to a source of pressure - blood. There are devices that consist of a needle connected by a special tube to a manometer (a device that indicates pressure). The needle is inserted directly into the bloodstream, the manometer at this time shows digital values corresponding to the force of pressure on the walls of the bloodstream.

Invasive methods of measuring pressure are used in surgical practice when it is necessary to constantly monitor the level of this indicator. This is the state of the patient when there is no time to put on a cuff, pump up air, and information about the work of the heart and blood vessels plays a vital role.

The method of direct measurement of pressure in the arterial network is, of course, the most objective and truthful. However, it is impossible to monitor the level of this indicator in this way all the time. This requires penetration of the sensor of the measuring device directly into the bloodstream. The role of such a sensor is performed by a needle. This manipulation requires medical skills, is traumatic and painful for the patient.

Methods for measuring pressure in a non-invasive way are widely used:

auscultatory method of Korotkov;
oscillometric method.

From the name auscultatory, the principle of the method is clear. It is based on the auditory fixation of tones that are heard during the passage of the blood flow inside the vessel. A pneumatic cuff is applied over it, pressing it down during the measurement procedure. The mirror of the phonendoscope is superimposed on the artery below the site of clamping. Having fixed the first tone by ear, the doctor simultaneously notes the digital value on the display of the pressure gauge attached to the cuff. This figure characterizes the systolic pressure of the patient.

As the blood flow normalizes, the tones become muffled, then they are not at all noticeable to hearing through a phonendoscope. The last sound heard must also be recorded on the pressure gauge scale - it will correspond to diastolic pressure.

The advantages include the relative simplicity of the procedure, the availability of devices for purchase in the pharmacy network. The auscultatory method does not require a special place or additional equipment. A certain subjectivity can be considered a disadvantage - it depends on the hearing acuity of the person measuring, on the serviceability of the tonometer and the sensitivity of the phonendoscope.

The oscillometric method for measuring blood pressure according to the sorem principle does not differ much from the Korotkoff method described above. Its main difference is the absence of dependence on the state of the auditory system of the measuring.

With the help of a device - an oscilloscope that captures the frequency of blood pulses - the readings are reflected on the display of the tonometer. Sensors that measure the level of fluctuations are located in the cuff, which compresses the artery with the help of pumped air, then gradually deflates, allowing blood to pass more freely through the vessel. These fluctuations are recorded by the device. The first shock, the strongest, corresponds to systolic pressure, the last, which the oscilloscope is able to fix, corresponds to diastolic.

The main advantage of this method of measurement is the independence of the presence of the operator. The patient is able to independently measure pressure. To do this, you need to put on a closed cuff on your shoulder and turn on the device. Inflating air, its descent and fixing the results are carried out automatically, there is no need to listen to the tones with a phonendoscope. In addition, today there is a wide variety of models of such devices on sale. And another plus is that you do not need to have any skills to carry out the procedure.

However, there are also disadvantages that do not allow unequivocally recommending this particular method for determining blood pressure in a wide range of patients. The rather high price of the device compared to mechanical models limits its mass availability. In addition, automatic oscilloscopes are very dependent on the condition of the batteries they run on. With a short service life, the charge drops, which affects the accuracy of the readings.

Measurement of blood pressure is an important diagnostic method of examination. Measurement of blood pressure is considered by doctors as the main pre-medical procedure, which, if necessary, it is important to be able to do it yourself at home.

Apparatus for measuring pressure

For these purposes, a special apparatus for measuring pressure, called a tonometer, is used. It consists of the following elements:

Sphygmomanometer;
Pressure gauge.

The main parts of the sphygmomanometer are a rubber cuff for clamping the artery and a balloon (pump) for injecting air. Manometers are spring and mercury.

Usually, tonometers are used to measure blood pressure using a stethoscope (stethoscope, phonendoscope). The measurement is made according to the auditory Korotkov method.

Basic rules for measuring blood pressure

Blood pressure must be measured, observing the following rules:

1. The room should be warm;

2. The patient should sit comfortably or lie on his back. Before measuring pressure, a person should rest for 10 to 15 minutes. It should be noted that in the supine position, the pressure is usually 5-10 mm lower than when measured in a sitting position;

3. Directly during the measurement of blood pressure, the patient must remain calm: do not talk and do not look at the pressure measuring device itself;

4. The patient's arm should be completely bare, the palm should look up and be located comfortably at the level of the heart. The raised sleeve of clothing should not put pressure on the veins. The patient's muscles must be absolutely relaxed;

5. The rest of the air is carefully expelled from the cuff of the pressure measuring device;

6. Tightly put the cuff on the arm, while not tightening it too much. The lower edge of the cuff should be located 2 - 3 cm above the bend in the elbow. Then the cuff is tightened or connected with Velcro;

7. A stethoscope is attached to the inner dimple on the elbow, tightly, but without pressure. It is best if it is with 2 ears and rubber (polyvinyl chloride) tubes;

8. In complete silence, with the help of a balloon of the device for measuring pressure, air is gradually pumped into the cuff, while the pressure in it is recorded by a manometer;

9. Air is pumped until the tones or noises in the ulnar artery stop, after which the pressure in the cuff is slightly increased by about 30 mm;

10. Now the air injection is stopped. Slowly opens a small tap at the cylinder. The air starts to come out gradually;

11. The height of the mercury column (the value of the upper pressure) is fixed, at which a clear noise is heard for the first time. It is at this point that the air pressure in the pressure measuring device decreases compared to the pressure level in the artery, and therefore a wave of blood can enter the vessel. Thanks to this, a tone is called (by sound it resembles a loud pulsation, a heartbeat). This value of the upper pressure, the first indicator, is an indicator of the maximum (systolic) pressure;

12. As the air pressure in the cuff decreases further, vague noises appear, and then tones are heard again. These tones gradually increase, then become clearer and more resonant, but then suddenly weaken and completely stop. The disappearance of tones (sounds of the heartbeat) indicates an indicator of the minimum (diastolic) pressure;

13. An additional indicator detected when using pressure measurement methods is the magnitude of the pulse pressure amplitude or pulse pressure. This indicator is calculated by subtracting from the maximum value (systolic pressure) the minimum value (diastolic pressure). Pulse pressure is an important criterion for assessing the state of the human cardiovascular system;

14. The indicators obtained using pressure measurement methods are recorded as a fraction separated by a slash. The top number is the systolic pressure, the bottom number is the diastolic pressure.

Features of pressure measurement

When measuring blood pressure several times in a row, you need to pay attention to some features of the body. Thus, the values of indicators during the subsequent measurement, as a rule, turn out to be slightly lower than during the first measurement. Excess of indicators at the first measurement can be caused by the following reasons:

Some mental excitement;
Mechanical irritation of the nervous network of blood vessels.

In this regard, it is recommended to repeat the measurement of blood pressure without removing the cuff from the arm after the first measurement. Thus, applying pressure measurement methods several times, as a result, average indicators are recorded.

The pressure in the right and left hand is often different. Its value may differ by 10 - 20 mm. Therefore, doctors recommend using methods for measuring pressure on both hands, and fixing the average values. Measurement of blood pressure is carried out sequentially on the right and left hands, several times, and the obtained values are then used to calculate the arithmetic mean. To do this, the values of each indicator (separately the upper pressure and separately the lower one) are added and divided by the number of times the measurement was made.

If a person has unstable blood pressure, measurement should be done regularly. Thus, it is possible to catch the connection of changes in its level due to the influence of various factors (sleep, overwork, food, work, rest). All this must be taken into account when applying pressure measurement methods.

Normal values, when using any method of measuring pressure, are pressure indicators at the level of 100/60 - 140/90 mm Hg. Art.

Possible mistakes

It must be borne in mind that sometimes between the upper and lower pressure, the intensity of the tones can weaken, at times significantly. And then this moment can be mistaken for too high pressure. If you continue to release air from the device for measuring pressure, the volume of tones increases, and they stop at the level of the present lower (diastolic) pressure. If the pressure in the cuff is not raised enough, it is easy to make a mistake in the value of the systolic pressure. So, in order to avoid mistakes, you need to correctly use the methods of measuring pressure: raise the pressure level in the cuff high enough to “press”, but releasing air, you need to continue listening to the tones until the pressure drops completely to zero.

Another error is also possible. If you strongly press the brachial artery with a phonendoscope, in some people the tones are heard to zero. Therefore, one should not press the head of the phonendoscope directly on the artery, and the value of the lower, diastolic pressure, must be fixed by a sharp decrease in the intensity of tones.

Arterial (blood) pressure is an important indicator of the state of health, the control of which should be carried out by everyone without exception. The procedure for measuring blood pressure is quite simple and does not require the involvement of medical professionals. But when it requires attention, accuracy, as well as strict adherence to the prescribed rules. Only in this case it is possible to speak about the reliability of the obtained results.

Rules for measuring blood pressure

To measure blood pressure, sphygmomanometers, better known as cuff tonometers, are used. Sphygmomanometry or tonometry is the main method for diagnosing arterial hypertension, high blood pressure. Blood pressure is not a stable (constant) value and often fluctuates throughout the day. True, these fluctuations in healthy people are insignificant.

Accurate diagnosis requires multiple measurements of blood pressure. With slight upward changes in pressure readings, it is necessary to repeat measurements for a long time (from one to several months). This practice will help to accurately determine the blood pressure characteristic only for a given person, familiar to his daily life.

High blood pressure is a risk of injury:

target organs.
Of cardio-vascular system.

Attention! For greater reliability of the result, at least two measurements of blood pressure should be carried out. It is usually impossible to establish a diagnosis only on the basis of patient complaints at the initial examination. Diagnosis of arterial hypertension is carried out only after medical examinations, laboratory and instrumental studies during repeated visits by the patient to a medical institution.

In the modern world, the role of mental stress and malnutrition is increasing. Therefore, hypertension becomes the number one problem for all mankind. According to statistics, hypertension is steadily growing. Even the government programs in many developed countries to combat this problem and the titanic efforts of qualified medical workers do not help.

Under such conditions, it is difficult to overestimate the awareness of the population and the practical acquisition of the necessary skills to measure blood pressure. This will help to maintain your own health to a certain extent.

Moreover, the process of measuring pressure is not a complicated manipulation, and today tonometers of various designs can be bought at any pharmacy.

Important! Pay close attention to the rules for measuring blood pressure. Remember that without following them, you will not get accurate indicators. This means that you will not be able to take effective measures against arterial hypertension, which poses a threat to health and even life.

Blood pressure. Measurement protocol - what is it?

For what reasons is it necessary to follow the measurement protocol?

Important! Please note that the following rules of this protocol apply to measurements by any, including the most modern tonometers.

Under what conditions should blood pressure be measured?

To accurately determine indicators, a number of suitable conditions are required:

calm comfortable environment;
room temperature is about 18 degrees Celsius;
adaptation of the patient to the conditions of the office within seven to ten minutes;
rest for the same time before the procedure in your home;
refusal to eat one and a half to two hours before measuring pressure.

Those patients who smoke, use tonic drinks, alcohol, sympathomimetics (for example, nasal and eye drops) should refrain from taking these medications, bad habits and foods for two hours before the planned procedure. The best option is a complete rejection of the above addictions, since we are talking about factors that significantly increase blood pressure.

Attention! There are many common misconceptions about blood pressure. So, it would be a mistake to assume that it depends on age. Simply, with age, the number of chronic diseases that can contribute to the development of hypertension increases.

Why does blood pressure increase? What is it connected with? Main risk factors.

The factors influencing the increase in pressure include physical and psycho-emotional stress. In some, after such loads, the pressure can increase by several tens of millimeters of mercury.

Why?

The body increases blood flow to the brain and those organs that are important at the time. With blood, oxygen and all the substances necessary for full-fledged work are supplied to them in order to compensate for the energy spent during exercise. In order for the blood flow to increase, the vessels spasm, the strength and frequency of contractions of the heart increase.

Note. However, in healthy people, blood pressure does not rise too high. After a short rest, it returns to its original level.

High blood pressure. When should action be taken?

An indication for the adoption of special medical measures is the factor of a prolonged and significant excess of blood pressure in excess of normal values.

What is the optimal body position for a blood pressure measurement procedure?

There are three positions in which pressure can be measured:

in a sitting position;
lying on your back;
standing pose.

Attention! It is very important to hold your hand correctly. Remember that the middle part of the cuff and the heart must be at the same level! Take this seriously, otherwise the results may be distorted.

We measure blood pressure. Sitting position

Sit in a regular chair or comfortable chair. Behind the back should be felt reliable support. Legs should not be crossed. Calm your breathing, as rapid breathing is a factor that changes readings. Relax your arm and place it in a comfortable position on the table with emphasis on the elbow. The hand must be motionless throughout the procedure. If the table is not high enough, use a special stand for your hand.

Important! Do not allow your arm to sag when measuring pressure.

What should I pay attention to when using an electronic tonometer?

The oscillometric technique has a serious drawback in that the electronic tonometer is extremely sensitive to the slightest fluctuations. Do not move your arm during the procedure and do not press the cuff against you so that the device does not respond to your breathing.

We measure blood pressure. How to choose a cuff?

The size of the arm affects the selection of the cuff. It should be measured in the middle of the shoulder with a centimeter tape. It is allowed to measure pressure with a standard tonometer with a conventional cuff in adults with shoulder volume indicators from 22 to 32 centimeters. If your performance does not meet this standard, order a special non-standard cuff for yourself.

The width and length of the elastic chamber in the cuff are also guided by the volume of the shoulder:

Length - 80% or more of this volume.
Width - at least 40%.

A smaller chamber width overestimates the pressure readings, while a wider one underestimates them.

In ordinary pharmacies, several types of cuffs are sold:

standard (ranging from 20 to 32 centimeters);
children's (from 12 to 20 centimeters);
large size (up to 45 centimeters).

Note. Most tonometers are subject to understaffing.

Try to follow the recommendations below:

Position the cuff a few inches above the crook of your elbow.
Make sure that the connecting tube is placed over the hole in the elbow.
Check if the cuff fits snugly enough and evenly.
Typically, most people's shoulders are conical, meaning they are wider at the top and narrower at the bottom. In view of this, put on the cuff a little obliquely - to ensure a uniform fit of the material on the surface of the arm.
Carry out the procedure for measuring blood pressure using a mechanical tonometer, after releasing your arm from the sleeve - clothing, when rolled up, can compress blood vessels, thereby disrupting blood circulation.
When using electronic blood pressure monitors, it is allowed to put on cuffs on loose clothing, this is their main advantage. Using a modern device, do not forget about its supersensitivity! Put on the cuff correctly and keep your arm in an immobilized position.

What to pay attention to when measuring the pressure of mechanical sphygmomanometers?

When choosing a mechanical sphygmomanometer to measure pressure, remember that it is necessary to adjust the decrease taking into account two millimeters of mercury per second.

If you are measuring blood pressure above 200 millimeters of mercury, you can increase the speed to five millimeters per second.

Advantages of electronic appliances

Electronic blood pressure monitors:

work in automatic or semi-automatic mode;
provide automatic control of the rate of pressure reduction in the cuff;
Contrary to popular belief, they do not always guarantee accurate measurements, even if the measurement rules are strictly followed.

Blood pressure. Method of measurement multiplicity. What's this?

Repeated measurement of blood pressure is allowed within two to three minutes after the previous measurement. This is the time required for the complete resumption of blood flow in the vessels.

Attention! The first visit of the patient to the doctor or the first independent study requires a mandatory measurement of pressure on both the left and right hand.

What to do if persistent and significant asymmetry of indicators is detected?

If we are talking about ten millimeters of mercury column and above for systolic blood pressure or five millimeters of mercury column for diastolic blood pressure, further measurements should be taken on the arm where higher values are diagnosed.

If the results of repeated measurements differ little from each other (the difference is up to five millimeters of mercury), the measurement does not make sense to continue. The indicator is averaged and taken as a basis for taking the necessary therapeutic and preventive measures, if necessary.

An increase in the difference from five millimeters of mercury and more is the basis for a third measurement. It should be compared with the second measurement. If you doubt the correctness of the result, take the measurement a fourth time.

Sometimes a cycle of studies shows a progression of pressure reduction. In this case, give the patient time to rest and calm down.

In the presence of multidirectional pressure fluctuations, it makes no sense to carry out further measurements. For the final diagnosis, the average digital indicator of three measurements is selected. In this case, it is necessary to exclude the values for the maximum and minimum.

Avoid Common Mistakes When Measuring Blood Pressure

There is a certain set of factors, ignorance of which leads to erroneous indicators and often does not allow diagnosing hypertension.

Pay attention to such points:

Don't buy cuffs that don't fit the size of your arm.
Use more time for adaptation before the first measurement.
Be sure to control the asymmetry of pressure on different hands.
Check the position of your body and the hand on which the measurement takes place, using the rules listed above in the text.

You should also take into account the possible inaccuracy of the readings in your pressure measuring device.

Measurement of blood pressure. Important conditions for obtaining reliable results

For the accuracy of the diagnosis and the reliability of the measurement results, three important conditions must be met:

Standardization.
Calibration frequency.
Periodic metrological check of the manometer.

When diagnosing, it should be taken into account that a significant part of the tonometers used in domestic clinics suffer from an error in a fairly wide range from two to fifteen points.

Blood pressure. Accounting for the human factor

There are clear recommendations for health workers and patients, accepted in world medical practice. However, in this matter, a clear and unified algorithm for measuring blood pressure has not yet been developed. This problem is typical not only for "third countries", but also for developed countries, including the United States,

For example, in American clinics, about half of qualified doctors and nurses measure blood pressure in patients in violation of the generally accepted method. The error in this state of affairs averages from fifteen to twenty divisions, corresponding to millimeters of mercury.

Arterial pressure. Factor of individual variability. What's this?

The maximum variability of readings when diagnosing pressure is shown by daily monitoring. Averages with it usually exceed those recorded in clinical conditions by 22 millimeters of mercury.

As one of the reasons, one can point to the so-called "white coat" effect (reaction to the cuff). This is a fairly common phenomenon, characteristic of the majority of patients (about 75%) who get an appointment with a doctor. This effect is more typical for women.

Acquisition of experience in the constant handling of pressure meters. Expert advice

Remember that a single measurement of blood pressure in most cases does not give an accurate picture of the state of affairs, which should be trusted.

In relation to arterial hypertension, overdiagnosis is often allowed - it is diagnosed where it is actually absent. In these cases, the patient at normal pressure takes antihypertensive drugs that reduce this pressure. As a result, health is harmed and the patient's condition deteriorates.

Learn to measure blood pressure correctly! Develop the necessary skills! This will save you from unnecessary medication.

Monitor your blood pressure every day several times.

Additional information for patients

Do not use wrist blood pressure monitors without your doctor's advice. The accuracy of these devices often leaves much to be desired.

Self-measurement of blood pressure is inconvenient and difficult for many. Therefore, it is better to turn to the help of health workers or relatives, acquaintances who have the necessary skills.

It should be borne in mind that blood pressure indicators obtained in different conditions will differ to some extent from each other.

How to make sure that the pressure was normal? Psychological advice

Your health in general and the normal level of blood pressure in particular directly depend on the psychological state. Good-natured and positive-minded people get sick much less than those who are always dissatisfied with everything. Remember that your thoughts shape your overall well-being.

Remember the joyful moments from your life more often and focus less on the negative aspects of life. Be not a bored skeptic but a romantic optimist. It will be much easier for you to endure not only great physical and psychological stress, but also quickly mobilize internal reserves to fight various diseases, it is easier to endure moral or physical pain.

Show love to the world, to strangers and close people. Don't get upset over the little things. What seems important to you now, tomorrow will not be even the slightest cause for concern.

Get creative. Knitting, drawing, reading books lead to contemplation and to a philosophy of calmness. A positive attitude along with good rest contributes to the normalization of blood pressure.

Useful video

Be always happy and healthy!

To measure blood pressure, a tonometer (sphygmomanometer) device is used, which consists of:

cuffs;
pump;
pressure gauge.

Tonometers are spring and electronic. To measure blood pressure with a spring tonometer, you need a stethophonendoscope. Electronic blood pressure monitors are semi-automatic and automatic. In semi-automatic - air is forced into the cuff manually, in automatic - by a compressor built into the pressure gauge. Electronic blood pressure monitors determine not only blood pressure, but also heart rate (pulse).

Rules and methods for measuring blood pressure:

Blood pressure should be measured:
- on the brachial artery of the left hand (tonometers that measure blood pressure on the wrist, even if all the rules are followed, give a large error);
- not earlier than 1 hour after sleeping, eating, drinking coffee, smoking a cigarette, drinking an alcoholic drink, exercising, taking a hot bath, showering, visiting a steam room, staying on the beach under the open sun.
The room where the pressure is measured should not be cold, hot or stuffy.
The tonometer should be at the level of the heart.
Do not talk while taking blood pressure. You need to sit on a chair relaxed, leaning back on the back of the chair, the left hand is relaxed, placed on the table near the tonometer, you should not cross your legs.
Before measuring pressure, it is necessary to determine by palpation (fingers) the point of maximum pulsation of the brachial artery (usually this point is located above the cubital fossa along the inner surface of the shoulder). In this place, during pressure measurement, a stethophonendoscope (if the measurement is performed using a spring tonometer) or a cuff sensor (if the measurement is performed using an electronic tonometer) should be placed. The cuff sensor is located near the rubber tube coming out of the cuff.
The cuff is fixed on the shoulder part of the arm above the cubital fossa with Velcro. When measuring blood pressure using a spring tonometer, the lower edge of the cuff should be placed above the location of the stethophonendoscope (place (point) of maximum pulsation of the brachial artery). The width of the cuff should be such that it covers approximately 2/3 of the length of the arm from the elbow to the shoulder.
In spring tonometers, semi-automatic electronic tonometers, air is pumped into the cuff with a pump in the form of a rubber pear at a speed of 2 mm. rt. Art. per second, focusing on the dial of the pressure gauge until the reading on the pressure gauge scale is 180-200 mm. rt. st.. In electronic tonometers, air is pumped into the cuff by pressing a button located on the pressure gauge, a compressor located in the pressure gauge. The cuff inflates and occludes the brachial artery. Further, the air from the cuff in electronic pressure gauges is automatically released and the measurement result is visible on the screen of the pressure gauge. After that, the rest of the air from the cuff is released using a valve located near the rubber bulb. In spring blood pressure monitors, air is released from the cuff using a valve located near the rubber bulb. At the same time, the appearance of heart tones (Korotkoff sounds) in the form of pulsating taps is listened to with a stethophonendoscope. At the same time it is necessary to look at the pressure gauge scale. The reading of the manometer corresponding to the appearance of Korotkoff's tones will indicate the value of systolic blood pressure. The reading of the manometer, corresponding to the cessation of the audibility of Korotkoff's tones, will indicate the value of diastolic blood pressure.
Note: When the cuff pressure is greater than the systolic pressure, no blood enters the brachial artery. When air leaves the cuff, the pressure in the cuff decreases and at a certain stage, pulsating blood begins to flow into the brachial artery. Turbulence and turbulence occur in the artery, creating a characteristic sound - pulsating Korotkoff tones, which are heard with a stethophonendoscope. These tones continue to be heard as long as the cuff continues to compress the brachial artery and prevents the free flow of blood through the brachial artery as long as the turbulent movement of blood in this area of the artery continues. After the pressure in the cuff decreases so much that it no longer interferes with the free flow of blood through the brachial artery, the Korotkoff sounds cease to be audible (the movement of blood through the artery becomes laminar (uniform)).

The work of the heart and the movement of blood through the vessels are accompanied by rhythmic changes in the volume of arterial vessels and the level of blood pressure. Therefore, knowledge of the level of blood pressure, its pulse fluctuations is very important for assessing the functional state of the circulatory apparatus. For the first time, the measurement of blood pressure in animals was carried out by Gales in 1733. For this purpose, he tied a brass tube into the artery, connected by a rubber hose to a vertically mounted glass tube. The horse's blood rose 8-9 feet, the dog's 4 feet. Poiseuille, assuming that Thales' data was incorrect, used a U-shaped mercury manometer connected to the artery with a rubber hose to measure blood pressure. Since then, blood pressure has been expressed in millimeters of mercury.

For a pressure of 1 mm Hg. Art./cm2 in honor of Torricelli adopted the symbol "torr". Poiseuille found that the blood pressure in a horse is 159 Torr, in a dog 151 Torr (or mm Hg/cm2).

Fig.1.

With the help of a Poiseuille manometer, Febvre in 1856 first measured the blood pressure in a person during amputation of the thigh and found it to be 120 Torr (mm Hg / cm2).

In 1876, Marey (Mareu) proposed an indirect method for determining blood pressure in humans. He placed the subject's forearm in a plethysmograph filled with warm water (Fig. 1). The plethysmograph O was connected to the tank P, suspended on block B and filled with water, and to a mercury manometer M with a float and a scribbler, with the help of which the change in pressure in the plethysmograph was recorded on the smoked tape of the kymograph K.

When the pressure in the oncometer reaches a value corresponding to the minimum pressure, the oscillation amplitude increases and continues to grow. At the so-called average dynamic pressure, the oscillations reach a maximum. Then they begin to gradually decrease until the moment corresponding to the systolic value. At this moment, the amplitude decreases abruptly (Fig. 2a).

Rice. 2 (a and b).
Designations: Mn - minimum, Cp - average, Ks - final systolic pressure; the numbers indicate the pressure in torr, other designations in the text

Marey's method required complex and fragile equipment, but nevertheless at first it seemed promising, since it made it possible to determine the value of the average dynamic pressure. However, the imperfections of the methodology limited the possibilities of using this method, and soon interest in it significantly weakened. The reason was that the method of reading, or decoding, waveforms proposed by Marey gave unsatisfactory results. On fig. Figure 2a shows a typical (according to Marey) oscillogram shape, which, according to Gley and Gomez (1931), was obtained only in 25% of all cases, and in fig. 2b - the most frequently obtained oscillogram, occurring in 75% of cases. It was not possible to decipher the last curve.

A fundamentally new technique for determining blood pressure was proposed by Riva-Rocci (Riva-Rossi, 1896). It consisted in compressing the brachial artery with a special rubber cuff 4-5 cm wide and 40 cm long, enclosed in a silk fabric case. The cuff was connected to a mercury manometer of the original design, and air was injected into it using a balloon. The magnitude of blood pressure was judged by the moment of disappearance and then the appearance of a pulse on the radial artery, respectively, during the rise and fall of pressure in the cuff, taking the average from these readings. As shown by numerous studies, the Riva-Rocci blood pressure values significantly exceeded its true value. According to Recklinghausen (Recklinghausen, 1901), errors in pressure determination decrease with increasing cuff width, and the best results can be obtained with a cuff width of at least 12 cm. According to Riva-Rocci, only systolic pressure was determined. In 1905 N.S. Korotkov, at an interdepartmental meeting of the Military Medical Academy, reported on the sound phenomenon he had discovered that occurs when the brachial artery is squeezed by the cuff. M.V. Yanovsky correctly assessed the practical significance of N.S. Korotkov and subjected him to a comprehensive study.

Thanks to the works of M.V. Yanovsky method N.S. Korotkov received universal recognition and firmly established in clinical practice around the world. The advantage of the sonic method is its simplicity and accessibility, it allows you to determine the value of not only the maximum, but also the minimum pressure.

The works of M.V. Yanovsky and co-authors found that if you raise the pressure in the cuff above the systolic one and then gradually reduce it, then at the moment of falling to a value approximately equal to or slightly less than the systolic one, tones appear in the distal segment of the artery - the first phase of the Korotkov phenomenon. With a further decrease in pressure in the cuff, the tones are replaced by noises - the second phase of "Korotkov" sounds. In the future, loud tones appear again - the third phase of the phenomenon, then their intensity decreases - the fourth phase, and, finally, the sounds disappear - the fifth phase.

A typical alternation of sound phenomena is not always observed. The noise phase is often absent. With increased blood pressure, it is often possible to observe the appearance of tones of the first phase, which then disappear and reappear when the pressure in the cuff decreases by another 10-20 mm Hg. Art. - the phenomenon of "failure". In the future, the sounds change in the usual way.

The sound phenomenon is especially atypical if the pressure in the cuff is gradually increased. Often, a sound, sometimes very faint, appears only at the moment when the pressure in the cuff reaches systolic. If you raise the pressure higher and then lower it, then all phases of the N.S. Korotkov’s sounds can be distinct, i.e., in the same subject, the sound phenomenon may be absent during compression and be well expressed during decompression.

The time during which the measurement of pressure according to N.S. Korotkov, should not be long - no more than one minute.

A large number of experimental and clinical works are devoted to clarifying the question: to what extent is the pressure determined by N.S. Korotkov, corresponds to the true values of blood pressure (Frank, 1930; Bonsdorff and Wolf, 1933; G. I. Kositsky, 1958; Kenner and Gauer, 1962). These studies consisted in comparing the data obtained by the method of direct direct measurement of blood pressure (arteriopuncture), with the data obtained by measuring arterial pressure by the sound method. It should be considered that when determining arterial pressure at rest, the appearance of the “Korotkovsky” sound during decompression quite accurately coincides with the value of the final systolic pressure, exceeding the value of the lateral systolic pressure by 10–15 mm Hg. Art. (torr). With regard to diastolic pressure, the question is still being discussed - whether the true value of diastolic pressure corresponds to the fourth phase of the "Korotkov" sounds, i.e. the moment of transition of loud sounds to quieter ones or the fifth phase, i.e. the disappearance of sounds. The American Heart Association believes that when diastolic pressure is determined at rest, by the moment when loud sounds turn into soft sounds, values \u200b\u200bare obtained that are 7-10 Torr (mm Hg) higher than diastolic pressure. When determined by the moment of disappearance of "Korotkov" sounds, the readings coincide with those obtained by the direct method.

The determination of blood pressure according to Korotkov-Yanovsky requires strict adherence to certain conditions. It should be carried out at rest, in a comfortable position for the study (lying or sitting). The arm should be slightly bent and placed at the level of the heart. Since 1925, the attention of researchers, especially in France and Germany, to the oscillography method proposed by Marey (Frank, 1930; Bromser, 1928; A.I. Yarotsky, 1932) has again increased. However, the imperfection of the technique limited the possibility of using oscillography. Subsequently, all oscilloscopes designed to determine blood pressure were built using the principle of a differential pressure gauge, but they were distinguished by a low natural frequency of the recording system and low sensitivity. The quality factor of the recording system has been significantly improved by using optical recording of mechanical movements. The optical method made it possible to significantly increase the sensitivity of the device.

In 1935 N.N. Savitsky, together with the staff of the Leningrad Institute of Fine Mechanics and Optics, developed a new type of very sensitive optical differential pressure gauge. The merit of N. N. Savitsky is that he developed in detail and scientifically substantiated a completely new method for reading oscillograms. He called the differential oscillogram obtained with the help of the device he created a tachooscillogram (tachus - fast, fast; oscillum - swing, oscillation; gramma - record) to emphasize that it is the first time derivative of the volumetric one. The tachooscillographic method for determining blood pressure differs from other oscillographic methods in that it is not changes in the volume of the vessel located under the cuff that are optically recorded, but the rate of these volumetric changes. In addition, the used optical registration significantly exceeds the sensitivity of other devices available.

The method of tachooscillography has become firmly established in clinical practice. It became available to determine not only diastolic, average dynamic pressure, but also true systolic (or lateral) pressure.