Can a mechanical tonometer show the wrong pressure. Why can the tonometer show the wrong pressure? The accuracy of determining blood pressure is affected

Electronic blood pressure monitors are used constantly due to their simplicity. The main problem of electronic devices is an unexpected reset of readings. Let's figure out why the tonometer does not show pressure and resets the available readings.

The principle of operation of the electronic tonometer

All tonometers have a similar principle of operation. It consists in measuring pressure by determining fluctuations in the cuff of the device, which occurs when "listening" to the blood passing through the veins. A special device is installed in the cuff, which is put on the arm in the area of the artery.

This principle of operation is the oscillometric method. Further, the obtained indicators are displayed on the second part of the tonometer - a mechanical pressure gauge or the main unit of the electronic version.

Device structure

As for the operation of the electronic device, the vibrations occurring in the cuff are analyzed by an automatic system, which translates them into digital values. Depending on the available functions, the electronic tonometer can display the following data:

indicators of upper and lower blood pressure;
heart rate;
determination of the presence of arrhythmias and other possible pathologies.

Automatic blood pressure monitor

In electronic varieties, you can use the previous saved data. Some models remember blood pressure readings up to 20-30 measurements.

The automatic blood pressure monitor has significant disadvantage in the form of an unexpected data reset. Such a nuisance can develop during the use of the device, and previously fixed indicators are also often “lost”.

Reasons for dropping indicators

If the electronic blood pressure monitor resets during use, we can talk about a serious malfunction. But often users themselves make mistakes. Therefore, among all possible causes The presented problem can be distinguished:

The device does not show all the data

complete malfunction of the device;
an error in the oscillometric method of measurement - there is a malfunction in the cuff;
the user jerked his hand, which caused a failure in the measurement of blood flow;
the user has arrhythmia - at this time the heart works irregularly, so the automatic system does not have time to measure the indicators and interpret them into numerical values;
other features of the user's body;
detachment of the cable of the main unit, which causes incorrect display of numbers on the display.

The features of the body include various disorders in cardiovascular system which is often seen in the elderly. In most cases, the tonometer shows different indicators, but may even reset values.

How to fix it?

Before correcting an existing malfunction, it is necessary to determine its cause. If it is a matter of incorrect pressure measurement, it is necessary to read the instructions again with recommendations for use. The basic rule in this case is not to move the hand on which the pressure is measured.

The user's actions in repairing the device depend on the cause of the malfunction:

Cable detachment requires soldering contacts

In order to avoid trouble or for subsequent possible free repairs, it is recommended that you choose to purchase devices from those brands that have their own service centers at the user's place of residence.

“Please help me sort out the situation! - A letter came to the editorial office of the Web Journalist the other day. My mother is already 79 years old. She often "jumps" blood pressure. I have been thinking about buying an electronic blood pressure monitor for a long time. Finally made up my mind last week. And what would you think? The first impression is that the thing is stylish, comfortable and very necessary. But ... The tonometer shamelessly "lies"! It was worth putting a cuff on the mother's wrist, as he showed 178/135. Horror! All the household members were jokingly alarmed. I had to call an ambulance...

Medics arrived, took out an ordinary blood pressure monitor with a “pear”, put a cuff on his shoulder. The pressure turned out to be… 125/90! He was measured again, and again ... Everything was normal! Why, then, did the readings of an electronic device (by the way, produced by a well-known Japanese company) go off scale? The doctor just shrugged… The next day I went to the pharmacy to exchange the device. But they assured me that everything was in order. Say, we measured incorrectly. Strange ... Tell me, how to be in such a situation? And is there a special service in Minsk that would check the accuracy of tonometers?..”

The question, of course, is interesting ... And very relevant! Today, about 15-20 models of blood pressure monitors are sold in shops and pharmacies in Minsk various types. These are not only traditional "pears" with a phonendoscope and a dial gauge. AT last years imported "machines" came into fashion. They are produced by AND, Microlife, Marshall, Nissei, Omron, etc. The measurement process, at first glance, will not cause any special problems. It is enough to press the button - and the tonometer will do everything by itself, and the result will be displayed on the LCD display. Comfortable? Of course! But, it turns out, not everything is so simple! ...

I have heard more than once that the spread in the readings of imported "automatic" and "semiautomatic" is very large. Let's say now the device shows 120/80, and after a few minutes - 135/95. How can this be? Unclear. Moreover, there is an opinion that devices that measure pressure on the wrist are not very accurate. But they are not cheap! Some hypertensive patients do not recognize imported electronic "toys" at all, preferring to measure blood pressure in the traditional way. Consumer fears are unfounded. All electronic blood pressure monitors, regardless of the manufacturer, model and design features, are highly accurate. Their error does not exceed plus/minus 3 mmHg. Then what's the matter?!

There are several reasons why the readings on the tonometer display are incorrect. Firstly, their dispersion arises from various interferences created by the movements of the hand or body (for example, knocking on the table). Secondly, the sensitive sensor responds to slightest change air pressure in the cuff (during the measurement, you can’t even talk!). Thirdly, great importance has the emotional state of the patient. Fourth, you must be able to properly apply the cuff. Finally, the measurement accuracy in some cases is affected by the type of this very cuff ...

Before buying a tonometer, consider the following. Devices that measure pressure on the wrist are not recommended for people over 50 years of age (vessels lose elasticity with age), as well as for patients who are too “obese”. The lower the pressure is measured on their arm, the greater the likelihood of inaccuracies. This is due to the unequal blood pressure in the arteries in the region. elbow joint and wrists due to different distances from the heart, as well as with the variability of the diameter of the vessels.

In addition, during the measurement it is very important to place the cuff exactly at the level of the heart. This is especially important when measuring blood pressure at the wrist. So, if the device is below the heart, then the result will be overestimated. And one more important point. Many people measure pressure several times in a row, and then determine the average result. This is not entirely correct. The break between measurements should be at least 7-10 minutes. This allows the blood vessels to regain elasticity. Never measure blood pressure with your arm in the air. Do not cuff your clothing or roll up your sleeves, otherwise the fabric will compress the skin, which will distort the result.

The correct selection of the cuff is another condition for the accuracy of measurements. All of them are equipped with Velcro fasteners for fastening on the shoulder or wrist, and are made of synthetic materials. The average arm circumference of an adult in the shoulder area is from 23 to 32 cm. The width of the cuff should be about 40% of this value (about 12-14 cm). It is also necessary that the length of the cuff pneumatic chamber is not less than 80% of the circumference of the limb (about 18-26 cm). Short and narrow cuffs can lead to higher readings.

Let's assume that you follow all the recommendations, but the tonometer still "lies". How to be? If desired, it can be verified in the metrological laboratory. Tonometers that are used in hospitals and clinics must be calibrated annually. As for home blood pressure monitors, this must be done once every three to five years. The reason for incorrect readings on the instrument display lies either in individual characteristics a person (some people generally “can’t stand” automatic blood pressure monitors), or that you are taking measurements incorrectly. Before buying a tonometer, check whether it has passed the pre-sale metrological control of the accuracy of the readings.

A tonometer is a device for measuring blood pressure. In order for the numbers of the device to be accurate, it is necessary to check the electronic tonometer, set it up, and also know the intricacies of its work. Such an adaptation should find its place not only among people suffering from hypertension, but in general should be in every family.

Correct pressure measurement

To measure pressure, you need to put a special cuff on your arm. It should be above the inner bend of the elbow by 1-2 centimeters. The cuff must fit the person in size. She should not strongly squeeze the hand, but also not “hang” on it. After that, independently or with outside help, air is pumped with a special rubber bulb. After that, the pressure will become known.

Enter your pressure

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Avoiding errors in readings when measuring pressure

Sometimes the tonometer can give incorrect data, so you always need to monitor its accuracy. First of all, you need to know that there are several types of devices:

Mechanical tonometer. It is more difficult for them to measure pressure - this should be done by a doctor or a person with very good eyesight and hearing, which can accurately recognize the sound of the pulse in the headphones and the desired indicator on the dial.
Electronic or automatic blood pressure monitor. This is a modern device that everyone can use - you just need to use it correctly, and it will display the pressure on the screen.

It is impossible to say which of these devices is more accurate. At correct application they both show the correct indicator. But in both cases, errors are possible. An electronic device will most likely fail when the battery is low. It is also impossible to get the correct result if the bulb, electronic unit or cuff is faulty. Calibration of the mechanical apparatus is also necessary. To avoid mistakes, before measuring pressure, you should refrain from drinking alcohol, coffee and strong tea, smoking, physical activity. You can not talk and measure the pulse in a state of excitement. To obtain accurate indicators, it is better to measure the pulse in the morning and evening three times, with breaks of 5-10 minutes. The lowest score will be the most accurate.

Setting up a tonometer at home

There are several tips on how to test the mechanism for serviceability at home. There is a special setting that shows a certain pulse and breathing of a person, which it imitates. The tonometer is calibrated according to these data. But such an installation is very expensive and not available to everyone at home. The second way is to connect two blood pressure monitors to one cuff, one of which will be fine-tuned by a medical technician.

The reference tonometer can be set up in a pharmacy, after which you can calibrate your technique according to these data. An accurate device is necessary in the house, because its indicators can help pay attention to the problem in time. It is necessary to check the equipment for malfunctions, and always observe the correctness of the correct pressure measurement.

It is no secret that blood pressure is an important indicator for the functioning of the heart, blood vessels, the entire body system and human viability. There will always be at least one person in the family who suffers from hypertension. Therefore, the house should have a tonometer for regular monitoring of the main indicator of health. Especially the apparatus is required by the elderly and those engaged in heavy physical labor. As a rule, devices are prone to breakdowns, especially often break mechanical types tonometers. Therefore, the problem of how to repair a tonometer with your own hands is quite relevant.

Device types

The considered devices are divided into three types. Each has certain modifications, and also differs from others in the principle of operation. All types have positive and negative sides. Mechanical offers high accuracy and low cost. But it takes skill to learn how to use it yourself. The semi-automatic is much easier to work with and breaks less often. Electronic blood pressure monitor has a higher cost and higher error. Even a child is able to measure the pressure with them. It is enough to put on the cuffs and press the button, after a while the result will be displayed on the scoreboard.

mechanical device

As a rule, the repair of devices consists in changing the component assembly. Why you need to buy a new mechanism and replace the broken one with it. For example, it is impossible to inflate the cuff with air. This means that the check valve in the pear has broken. It is pointless to change only the valve, you need to replace the entire assembly, along with the tubes.

Electronic machines and semi-automatic devices at a price several times higher than a mechanical device. These types of devices have not too frequent malfunctions. Often happens:

semi-automatic device

Serious breakdowns are best repaired at a service center, because a warranty card is issued for repairs, and it is forbidden to repair it yourself until it expires. You can change the bulb, cuff, batteries yourself, they are not covered by the warranty card.

The device is automatic

How to repair a tonometer correctly: features and recommendations?

If you decide to save time and money and fix the tonometer yourself, you must first find a malfunction in the device. If a person often uses it, then it will not be difficult to determine the broken part. If the problem is the passage of air from the system, then it must be detected. Having found a place for air passage, this element is simply required to be replaced with a new one. If after that the pressure measurement went well, then everything worked out.

How to repair a mechanical tonometer with your own hands?

What kind of breakdowns can a mechanical device have and how to fix them yourself:

You can buy the necessary part for a mechanical tonometer in the online store by ordering by phone, or in a medical equipment store.

Features of repair of electronic equipment

Breakdowns and methods of repairing an electronic type device:

It is not so easy to disable automatic devices. If you do not drop the tonometer, do not hit it and do not shake it with force, then it will last for many years. The electronics inside the camera are quite fragile and require delicate and careful handling.

Leaky cuff repair

If the problem is air bleeding, then you need to find the place of the gap. When it is located directly on the cuff, it does not have to be replaced, it can be repaired. How to repair the breathable cuff of the blood pressure monitor:

If the hole is small, and the cuff is strong and unworn, then you can solder it with a hot glue gun.
A piece of a patch made of rubber or other suitable material can be glued onto the gap with rubber glue.
Take a strip of thick aluminum and bend it in half. Insert the damaged area between them and clamp it with metal, help yourself with pliers. Cover this place with glue.

Replaceable cuff

When air escapes at the factory soldering point, it can be cured with a soldering iron at 180 degrees. It is important to remember that repairing the cuff is cheaper than replacing it, but it will not last too long after the intervention. Therefore, be prepared to replace this element.

How to properly disassemble the AND tonometer?

Tonometer model AND UB 201

The AND UB 201 tonometer is a wrist-type device for measuring blood pressure. Most often, this model fails the cuff. To repair or replace it, you must remove it correctly. This is done in the sequence:

Batteries are removed from the camera.
Remove the clips that secure the cuff (they are located on both sides of the case) by prying them with a screwdriver.
Pulling the cuff towards you, release it from the body of the tonometer, to which it is attached with two more latches.
The housing cover is attached with two bolts at the back, they must be unscrewed with a screwdriver. Carefully open the cover and remove it.
To completely disassemble the tonometer, you should press in the recesses at the top of the case with the same screwdriver, and it will easily fall apart.

Disassembly of the device case

The body is assembled in the reverse order. It is important to put all its details in place and fix them on special “pins”.

The question is considered in detail, if the tonometer does not work, what to do. You can contact the service center and hand it in for repair, but it will take a lot of time, extra money will be spent. The breakdown associated with the replacement of any element can be eliminated by yourself - buy a new part in a medical equipment store and replace the faulty one.

Semi-automatic and automatic devices.

Previously, the main devices were mercury. The cuffs of blood pressure monitors in the process of measuring blood pressure can be located on the wrist or forearm. Blood pressure is measured in millimeters of mercury (mm Hg). But what if the tonometer does not show pressure, or gives different readings? And how to check the tonometer for accuracy?

To estimate blood pressure, you need to know the initial data, which look like this:

lowered Blood pressure is considered in cases where the upper indicator is 100-110, and the lower one is 70-60 mm Hg. Art.;
optimal- 120/80 mm Hg. Art.;
slightly elevated- 130-139 / 85-89 mm Hg. Art.;
high- 140/90 mm Hg. Art.

With age, blood pressure, as a rule, changes upward due to changes in vascular throughput.

Normal pressure is considered at the following values:

in 16 - 20 year olds- 100-120 / 70-80 mm Hg. Art.;
in 20-40 year olds- 120-130 / 70-80 mm Hg. Art.;
in 40 - 60 year olds- less than 140/90 mm Hg. Art.;
over 60 years old- less than 150/90 mm Hg. Art.

For the correct determination of blood pressure, the following rules must be observed:

at least 5 minutes the patient should be in a calm and comfortable environment;
an hour before the procedure, he should not eat, drink or, as well as smoke;
his bladder does not have to be complete;
after emotional outbursts, you need to wait at least an hour;
during the measurement, do not talk, sit straight and have support under your back;
do not cross your legs so as not to pinch large vessels and not interfere with the flow of blood;
the cuff should not hang out or pinch the arm tightly;
The cuff should be at heart level and two centimeters above the elbow.

Violation of the elementary conditions for measuring blood pressure leads to erroneous values. The error can reach 20-25 mm Hg. Art.

Users sometimes encounter situations where the tonometer does not show pressure. The reasons that the tonometer does not show pressure can only be found out by a specialist, how to answer certain questions regarding the operation of the device.

Tonometer shows different pressure

If you can put up with the difference in the readings of the device after measuring blood pressure at long intervals, explaining them by different conditions under which measurements are taken (time of day, physical state person, etc.), then the discrepancy between the results when measured after 5-7 minutes makes you think.

Meanwhile, there are reasons for this.

Errors can occur due to the characteristics of the device itself, its improper use, measurements with different devices, the position of the cuff relative to the heart, the state of the power supply of the electronic device, physiological features body (vessels are located deep, large body fat, low elasticity of blood vessels, etc.), as well as the posture of the patient and his behavior during the procedure.

The readings also change due to the fact that the walls of the blood vessel, squeezed by the cuff during the previous measurement of blood pressure, adapt to decompression and do not have time to return to their original state, which affects the blood flow and its parameters.

If in young people the restoration of arteries occurs in a few minutes, then in the elderly this time increases to 10-15 minutes.

Therefore, blood pressure measurements must be carried out strictly according to the instructions, with one device, and also taking into account age, and keeping calm while waiting for a second procedure.

The most accurate results are obtained after three measurements at set intervals and averaging the instrument readings.

Why does the tonometer take off when measuring pressure?

Sometimes in the process of measuring blood pressure, a sharp zeroing of the tonometer readings occurs. The reasons for this are:

failure of the device;
failure (error) of the oscillometric method of measurement, which is the basis for the operation of the vast majority of electronic semi-automatic and automatic tonometers;
involuntary movement of the arm, on which the cuff of the electronic device is fixed, the operation of which is based on the oscillometric method of measurement;
arrhythmia, when the heart works irregularly, and the time interval between individual “beats” may not be enough to trigger the electronic tonometer sensor;
characteristics of the patient's body, as mentioned above.

Regardless of the type of tonometer used, if there is any doubt about the accuracy of its operation, it is necessary to contact the metrological laboratory for verification. All sold devices undergo such control during pre-sale preparation.

The oscillometric principle of measuring blood pressure is associated with the pressure in the cuff, which changes during the pulse push and its absence. Under the influence of this pressure, the volume of the limb under the cuff changes, which is detected by the sensor located in it.

The signal from the sensor enters the "brain" of the device, where it is processed and converted into visible numbers that tell us about the actual blood pressure. Since this method is associated with the pulse, then its value is also given by the device. The movements of the patient or his arm, on which the measurement is carried out, affect the pressure in the cuff, which affects the operation of the device and the accuracy of its readings.

The principle of measuring blood pressure according to Korotkov (auscultatory method)

Such a phenomenon is impossible in mechanical devices, the operation of which is based on the auscultatory method of measurement. Its essence lies in listening to the noise associated with the movement of blood. In the process of forcing air into the cuff of the device and bleeding it, noises arise, grow, weaken and disappear, which are captured by the phonendoscope.

The specialist at a certain moment records the readings of the device corresponding to the upper and lower pressure values. He must have good hearing and experience in the use of such a device. The accuracy of measurement largely depends on his abilities.

Why are there different readings when measuring pressure?

The tonometer, like any measuring device, has errors associated with the method underlying its operation.

The accuracy of determining blood pressure is affected by:

the rate of air pumping into the cavity of the cuff and its bleed;
the amount of pressure created in the cuff;
natural fluctuation in blood pressure, which can change quite quickly;
time between measurements;
use of different devices;
measurement on different hands;
type of cuff and more offset relative to the heart;
the behavior of the patient during the procedure (talking, sneezing, raising the arm with the cuff and his emotions, changing the position of the body, etc.).

When using a conventional (mechanical) tonometer, the measurement accuracy also depends on the professionalism of the person conducting the procedure, since not everyone is able to catch noises and their changes in a phonendoscope. Especially striking differences in the readings of a mechanical device are observed when the pressure is independently determined.

Here, the applied efforts, the tension of attention and the regulation of the rate of pressure release in the cuff affect. The influence of the human factor is significantly reduced when using an electronic tonometer, which explains its increased accuracy.

Human emotions cannot be discounted. If his first measurement showed an increased (decreased) pressure value, then involuntary excitement sets in, which will certainly affect the result. re-measurement.

The pressure can rise even at the sight of a person in a white coat taking measurements.

While waiting for the second measurement, the patient calms down, his blood pressure returns to normal, which is shown by the repeated procedure. Related to this is that many people are trying to get rid of non-existent.