Why is the tonometer not showing? When can a tonometer show pressure incorrectly? Features of measurement by a semi-automatic electronic tonometer

Why does the tonometer show different pressure? This is often asked by users when buying a new electronic device. And it also happens that it shows different blood pressure (BP), if you measure it several times in a row. It turns out that there are many reasons for this.

Tonometers are special medical devices that measure blood or eye pressure. In the latter case, the device is called a pneumotonometer. Such devices are an indispensable attribute of doctors. However, today many people, especially those suffering from hypertension and heart disease, successfully use devices for measuring blood pressure at home. They even recommend a tonometer, because patients should always keep their blood pressure under control in order to avoid complications caused by an increase in blood pressure.
The tonometer readings are recorded as two measurements, for example, 120/80 mm Hg. Art. What do these numbers mean? This is a different pressure created in each of the two phases of the heart. The first reading is the highest blood pressure pumped by the heart. In our example, this is 120 - it is called systolic. The second reading is the minimum. It is observed in diastole, when the heart relaxes, fills with blood, then to push it out. This “lower” pressure is referred to as diastolic.

The device does not show pressure

Tonometer shows different pressure

The automatic blood pressure monitor responds to such factors:

The sensitive sensor reacts even to the movement of air. Be calm, don't talk, keep your back straight. The cuff of the tonometer, fixed on the arm, should be at the level of the heart. If you remove all the interference, follow the instructions, the result will be correct.
If you need to get a more accurate result, you can take measurements three times with the necessary break between them. After that, it is important to derive the arithmetic mean. It must be remembered: the first indicator and the last may differ due to the artery getting used to compression or any involuntary movement, so triple measurements will give more accurate data.
It must be remembered that a decrease, as well as an increase in pressure beyond the norm, is an alarm signal. It is necessary to find out the reason by contacting a cardiologist.

Very often, blood pressure monitors may not give out at all or show an incorrect result, as well as show different pressures for various technical reasons:
forgot to insert batteries;the device is not used correctly;
low-quality batteries that quickly fail.
In order for electronic blood pressure monitors to work well, it is necessary to change the batteries on time. It is recommended to use for meters blood pressure only alkaline (ALKALINE) batteries LR. They are more energy intensive and guarantee a long service life, which is from 200 to 400 measurement cycles. Here, the word cycle means 2-3 times a day. Batteries LR, regardless of the manufacturer, will ensure the operation of the tonometer for 4-6 months.
When the tonometer is turned on, the display is tested, and if the device showed a symbol that indicates insufficient power, this means that the batteries are low - it's time to take care of new batteries.
In addition to the errors associated with the measurement of blood pressure by the device, and technical reasons, different pressure can be quite physiological. It is worth remembering that active movements, transferred loads, even sneezing and coughing increase blood pressure. This is a natural reaction and does not require medication. Blood pressure rises for a short time, and if you repeat the measurements a little later, the indicators will drop significantly.

Hello dear friends!

Today, as promised, we will talk about blood pressure monitors. It seems to me that after a detailed conversation about hypertension, it is logical to talk about meters.

Perhaps, for many of you, the choice of a tonometer is not particularly difficult.

And wonderful!

Therefore, I will be very glad if you also find something valuable for yourself in this article.

But I know that thousands of people who have nothing to do with pharmaceuticals daily type in the search engine the phrase “how to choose a blood pressure monitor?” And who knows, maybe they will come across just this blog.

Therefore, here I would like to give the most detailed information on how to choose the right blood pressure monitor for yourself and your loved ones, so that later it would not be excruciatingly painful for the money thrown to the wind.

What will this conversation be about?

First, we will analyze what blood pressure monitors are and how they work.

Second, let's think about eternal question customers "Which blood pressure monitor is better?"

Thirdly, let's think about what questions you need to ask a buyer who wants to buy a tonometer.

Fourth, let's remember how to measure blood pressure correctly.

Fifthly, we will analyze the most frequent questions of buyers and decide how to answer them.

Well, are you ready?

Then let's get started.

What are tonometers?

Look at this diagram:

So, all blood pressure monitors are divided into mechanical, semi-automatic and automatic.

The latter are on the shoulder and on the wrist.

A long time ago there was still a mercury tonometer, which was the most accurate, because, as you know, blood pressure is measured in millimeters of mercury.

These are the same millimeters he showed.

We used to have one like this at home. After the first heart attack, the doctors strictly ordered dad to regularly measure blood pressure, and somewhere my mother got a device with the beautiful name “Riva-Rocci mercury sphygmomanometer” (this is the name of the Italian doctor who invented it).

When my sister and I were studying in medical institute, the very first thing we learned to do from medical manipulations- measure pressure, because we had regular home practice.

But this device was not safe. I remember that we accidentally crushed the glass column of the device, closing it incorrectly, and droplets of mercury escaped. So mom had to get another one.

The mercury ones were replaced by mechanical tonometers.

First, they are more compact. Secondly, safe. And thirdly, they are as accurate as their progenitor.

In a mechanical tonometer, everything has to be done by the person measuring: both inflate the cuff and deflate it, noting the number on the pressure gauge scale when the pulsation begins (this is systolic pressure), and the number when it stops (this is diastolic pressure).

The principle of operation of a mechanical tonometer

When the air pressure in the cuff becomes higher than the blood pressure in the vessels, the blood flow in the brachial artery stops. We do not hear any tones in the stethoscope tube.

Then, when the air descends, the lumen of the artery opens slightly, blood flow is restored, and Korotkoff sounds appear in the tube.

After a few seconds, the air pressure in the cuff drops so much that the artery is fully opened and the murmurs disappear.

Korotkov Nikolai Sergeevich is a Russian surgeon who, at the beginning of the 20th century, was the first to invent an auscultatory method for measuring blood pressure, that is, by listening with a stethoscope. Previously, this was done by palpation (with the help of fingers - as we feel the pulse).

Semi-automatic blood pressure monitors

In these devices, the pressure, as in mechanical ones, is pumped with a pear. But then the tonometer does everything by itself: it releases air and displays the result on the screen.

Automatic blood pressure monitors

Well, you don't need to do anything in these devices yourself. No, I'm lying. Need.

Click on the big button. And that's all!

The automatic blood pressure monitor will do the rest of the work for the person: it will pump air into the cuff, deflate it, and show the result.

The principle of operation of semi-automatic and automatic blood pressure monitors

These instruments use the oscillometric method for measuring pressure.

Fluctuations (oscillations) in blood pressure in the artery of the arm, which occur when air is released, cause air oscillations in the cuff put on the arm, which is recorded by a special sensor of the device and then processed by the built-in microprocessor.

What is the best tonometer?

What do you think, friends?

When I hear in a pharmacy that some visitor asks for a mechanical blood pressure monitor, because the attending physician said so, I really want to see him. Allegedly, only such a tonometer is accurate, and all the electronics are lying.

A few years ago, I was on training at Omron, and of course, we were also interested in this issue. We conducted an experiment: one and the same colleague measured the pressure with the help of an automatic device and with the help of a mechanical one. The result was, as they say, a tyutelka in a tyutelka.

Why did the results match?

Because:

Measuring blood pressure with a mechanical sphygmomanometer is a medical procedure!!!

In that training, I learned amazing thing: it turns out that in Japan for half a year they teach doctors how to measure blood pressure. Can you imagine? HALF A YEAR!

And in our country, every granny of 70-80 years old believes that there is nothing complicated in this.

If I had my way, I would release mechanical blood pressure monitors only after presenting a diploma from a medical school.

And that's why.

Once a study was conducted among ordinary people, never doctors, who measured their blood pressure with a mechanical tonometer. It turned out that 75% such measurers were incorrectly identified by Korotkov's tones.

And it’s okay if another person measures the pressure with such a tonometer. But people manage to measure themselves! And one pumping of a pear increases the pressure by 10-15 mm Hg!

In addition, let's not forget that older people have vision and hearing problems. Didn't see it, didn't hear it.

It also happens that the pressure gauge was lying on the table, and was not attached to the cuff, and this also distorted the results.

Or the measurer bled air too quickly and did not catch the first and last digits.

Some people, when measuring pressure, are guided not by tones, but by the fluctuations of the pressure gauge needle. But this is wrong!

Among other things, when the filling of the pulse is weak, and this often happens in the elderly, there can be complete silence in the tube. And then the person is frightened, and his pressure rises even more.

So I'll list...

9 reasons why I do not advise non-medical people to buy a mechanical blood pressure monitor:

1. A specially trained person should measure the pressure with a mechanical tonometer.

2. 75% of measurers incorrectly determine the pressure.

3. Decreased hearing and vision increase the likelihood of error.

4. Measurement of pressure to oneself increases it by 10-15 mm Hg. Art.

5. Incorrect gauge position increases the chance of error.

6. Excessive inflation of the cuff and rapid deflation will affect the correct result.

7. With a weak filling of the pulse, the tones in the tube are not audible.

8. Repeated pumping of air into the cuff during the measurement process, in order to catch the first and last tones, greatly distorts the result.

9. Few people know that a mechanical tonometer must be calibrated annually (adjusted to a standard) at a service center.

You say, so what, do not sell them, or what?

Of course, to sell: to doctors even in the case when none of your arguments convinced the buyer.

What about automatics and semi-automatics?

Buyers are always interested in the question, how accurate are electronic blood pressure monitors?

Their error is only 3-5 mm Hg. This number is not significant at all.

They are designed specifically for home use by people without a medical background.

If we compare automatic and semi-automatic machines, let's reason logically.

1. A person also inflates the bulb of a semiautomatic device on their own, which means that this is again physical activity, which can affect the result of the measurement.
2. If we talk about a very elderly person, then it’s hard for him to work with a pear: the muscle strength is no longer the same. Isn't it easier to get him a really light and easy-to-use device? I mean automatic.

As you can see, I'm for automata. For a long time I myself use only automatic devices. And I have two of them: AND and Omron. And both have been working for 100 and 1 year, and I have no complaints about either one or the other.

The only thing that deters some buyers from buying a machine is the price (except for the opinion of their doctor, which I have already mentioned above).

But five(for Omron) and ten(for AND) years of warranty speak for themselves. And, as a rule, these devices last much longer.

Divide the price of the tonometer by the warranty period, and it turns out that a person spends mere pennies on himself per month. Carry out these calculations together with the buyer.

About blood pressure monitors on the wrist

A few more words about blood pressure monitors on the wrist.

At the same training that I mentioned, we were very interested in the issue of the accuracy of blood pressure monitors on the wrist.

Omron believes that wrist blood pressure monitors are as accurate as upper arms and can be recommended regardless of age.

And then we also followed the principle of “trust, but verify” and measured the pressure of the same person with shoulder and carpal tonometers. The result was again the same.

But, nevertheless, after working for 9 years in pharmacies, I realized that it is better to offer wrist devices to people up to about 40 years old. And that's why:

1. With age, the vessels wear out, and the vessels of the wrist are faster because they are thin. The elasticity of their walls decreases. And for an accurate measurement, they need to be in good condition. The brachial artery is more enduring in this regard, which means that it is better suited for capturing oscillations (oscillations).
2. In an elderly person, various microtraumas in the area of ​​the wrist joint (sprains, bruises, etc.) can “accumulate” during their life. This is a contraindication to the use of wrist devices.
3. With aging, various joint deformities occur, “bones” appear, which leads to incorrect application of the cuff of the device.

Did you expect me to tell you about the notorious atherosclerosis? I will not say, because atherosclerosis affects large and medium-sized arteries. Carpals are not one of them.

Now we will analyze what questions a buyer should ask when buying a tonometer.

1. Who are you taking for? We ask in order to understand for a person of what age the device is purchased. If for a person of young and middle age - you can offer both shoulder and carpal. If for the elderly - only the shoulder.
2. Are there irregular heartbeats (arrhythmias)? If “yes” or “don’t know”, then we offer only with the smart measurement function. If not, then any.
3. If they don’t take it for themselves, we ask, is the person’s hand full? If a person finds it difficult to answer, we offer a tonometer with a universal cuff. If for ourselves, we immediately figure out, according to the person’s complexion, which cuff is needed here.
4. How many people will use the tonometer? If two, we offer with memory for two.
5. If you have a relatively young person in front of you, ask where do you plan to use it? Houses? Traveling? For trips, compact models such as wrist or small semi-automatic devices are better suited.
6. Is it important for you to remember the date and time of the measurement? If yes, choose models with fixation of the date and time of measurement.

I didn’t write about “memory”, since this function is available in most modern blood pressure monitors.

These are basic questions.

You can download this algorithm by clicking on the picture:

What is the smart pressure measurement function?

The function of intelligent pressure measurement is probably provided now in tonometers of any trademark.

It means that with each pressure measurement, the device itself determines the optimal level of air injection. It measures pressure already in the process of air injection, analyzes the pulse wave in detail and, in case of arrhythmia, selects the fragment with the most stable pulsation so that the measurement result is as accurate as possible.

How to measure pressure correctly?

Here's how it should ideally be:

Below you see a very useful table. To download it as a Word file, click on it.

I advise you to print it, and even better, laminate it and show it to the buyer.

Very important!

When you measure the pressure of a customer in a pharmacy, tell him that you are now only checking the operation of the device and explaining how to use it.

You don't measure blood pressure! Since there are many factors that affect pressure figures.

This way you prevent objections:

- The device is lying.

I don't have that kind of pressure.

- Why so high?

I believe that the measurement should not be carried out on oneself, as many pharmacy employees do, but on the buyer.

1. Firstly, due to the characteristics of cardiovascular disease, the tonometer can constantly give an error, and by checking the operation of the device on the buyer, you will understand whether this model suits him or not.
2. Secondly, you will see if the cuff is too small.
3. When the pressure is measured on the buyer, he is already mentally “related” to it and imagines how he will use it at home. Therefore, such a sale is easier.

Frequently Asked Questions

1. On which arm should blood pressure be measured?

First you need to determine if there is a difference between the pressure readings on both hands. If it is not more than 10 mm Hg. Art., can be measured on any. It will be convenient for right-handers to measure on the left hand, for left-handers - on the right.

But first you need to take a few measurements on both hands.

If the difference exceeds 10 mmHg, the measurement should be on the arm with the higher numbers.

2. Why is the pressure on both hands so different?

This is possible with serious vascular pathology: narrowing, plaques, blood clots.

Go to the doctor and get tested!

3. Why how many times I measure pressure, the tonometer shows different numbers?

Because pressure is not a constant value. We talked, sat down, got up, walked around, ate, got nervous - all this is reflected in the pressure.

That is why doctors recommend taking three measurements with an interval of 2-3 minutes and taking the average value. Many modern blood pressure monitors have such a function: the device itself calculates the average pressure. It is very important, if you measure pressure 3 times in a row, to take this 2-3 minute break between measurements. Vessels should rest from squeezing and recover. Otherwise, the results will be incorrect.

4. Why, when a doctor measures my blood pressure, do I have different numbers?

Because in the clinic it is impossible to create conditions for the correct measurement of pressure (see above). At the doctor's appointment, you are, one way or another, nervous. There is even such a term: “white coat syndrome”. Therefore, more accurate measurements of blood pressure are in a calm home environment.

5. Are more expensive blood pressure monitors (within the same brand) more accurate?

No. All of them are accurate, and their price depends on the set of additional functions.

6. Why is a Japanese blood pressure monitor made in China?

Because the labor force is cheap in this country. If it were collected in Japan, it would cost twice as much. There is a huge difference between artisanal Chinese production and factory production. The assembly of tonometers takes place under the strict control of Japanese specialists. The quality of the tonometers is evidenced by the certificates of the Ministry of Health and the State Standard. And the service life of the devices reaches 20 years.

I will wrap up on this.

How did you like this article, friends?

Probably missed something. It's a very broad topic.

If you have something to add, add it!

Have questions, ask!

If there were difficult cases on this topic, tell us!

And lastly, I'll ask...

And finally, I invite you to think and answer these questions:

1. What should be done/said to the buyer in order to, if possible, insure himself against returning the tonometer?

2. In which case do you offer semi-automatic?

3. What is special about the cuff of Omron blood pressure monitors? What is the benefit for the user?

4. In what case will you offer the buyer a tonometer with the "Talking Assistant" function?

5. What is the meaning of the additional options "calendar" and "clock" in some models of blood pressure monitors?

6. Does the man in the main picture for this article measure the pressure correctly? 🙂

You can download tables for Omron and AND blood pressure monitors by clicking on the pictures below.

Tonometers AND:

Omron blood pressure monitors:

I got very impressive tables on them, you can remove from them those models that you do not have and, most likely, will not have. It will be easier for you to print them.

And look at the tabs below: automatic, semi-automatic, wrist.

I think that the article will be of interest not only to pharmacists, but also to all people who have a heart and blood vessels. 🙂

So do not take it for work, click on the social buttons. networks that you see below, share a link to this article with your friends and family.

And I say goodbye to you until we meet again on the blog ""!

With love to you, Marina Kuznetsova

P.S. I give a complete algorithm for selling a tonometer in my book “The ABC of Pharmacy Sales”. Details

I welcome everyone! I continue to summarize and spread in a compressed form my experience in electronics repair. I bring my Top 10 most common malfunctions of blood pressure monitors, which was born as a result of accidental repairs of medical equipment and communication with other Masters. I will not say that I am a great specialist in this area, but I came across something and successfully repaired it. Let's start the ranking. Fault locations for tonometers and blood pressure monitors are sorted by the frequency of occurrence of the fault.

1st place - loss of tightness of the tonometer cuff

If there is a loss of tightness in the pressure injection circuit in your tonometer, then with a high probability the error “Err Cuf” will be displayed on the automatic screen. Translated from English, cuff is a cuff, so it is logical that the Err Cuf error is a cuff tightness error.

If your blood pressure monitor gives such an error, then first of all you need to check the connection points of the cuff with the compressor. To do this, remove the cuff. Let's consider how to do this using the AND UB-403 wrist tonometer as an example.

How to disassemble an automatic blood pressure monitor on the wristAND UB-403

When turned on, this blood pressure meter reads zero.

Then the cuff is inflated, but it is interrupted and the Err Cuf error appears on the display.

We turn the AND UB-403 tonometer sideways and see the plug, which must be removed by prying it with a thin slotted or awl.

On the other side of the case, remove the same plug.

Here's what these cuff attachment plugs look like.

After that, we remove the cuff of the AND UB-403 tonometer and see the connection points of the pipes from the compressor to the cuff - there are two of them.

In these places, decompression and air leakage can occur, so we carefully inspect and clean the sealing rubbers of the tonometer pipes and cuff.

Let's try to assemble everything in reverse order.

If the cuff error remains, you need to check the cuff itself for cracks. This is usually done visually.

The rubber cuff of the blood pressure monitor can be repaired by gluing a patch to the place of the air leak. About, how to put a patch and repair the cuff, see below in the video on the example of the cuff of the Microlife tonometer.

How to glue the pillow of the tonometer

It happens that decompression of the air supply occurs inside the device. In this case, you will have to disassemble the tonometer and eliminate microcracks or change dried rubber bands.

If you do not understand the disassembly of the tonometer, then I advise you to watch the following video how to parse AND UB 201 .

2nd place - segments of numbers on the tonometer display disappear

Another part of the disease is detachment of the LCD cable blood pressure monitors, as a result of which segments of numbers and letters may not appear on the display.

The cables of the tonometer displays are glued according to the same principle. Repair is facilitated due to the pleasant size and pitch of the cable contacts. Repairing such plumes is much easier than in.

After disassembling the tonometer, you can glue the display cable back by uniform heating using a hot air gun or soldering iron to repair cables. Watch the video on this topic - very informative and interesting.

Repair and restoration of the Sanitas tonometer LCD display

Display repair if segments of the OMRON MX2 Basic tonometer disappear

3rd place - tonometer buttons do not work

in automatic and semi-automatic blood pressure monitors work is managed with the help of . These buttons do not last forever and fail over time - they are not pressed, they dangle, they are pressed without a click, they are pressed with a click, but without result.

If the tonometer button is faulty, you have to disassemble the device, disconnect the electronic board, solder the old one and solder the new button. In principle, nothing complicated, just need select exactly the same button, because there are a lot of seats, shapes and sizes of buttons.

For an example of common buttons, see the video on disassembling and replacing the tonometer button.

Repair of tonometer OMRON M3 Expert

4th place - the tonometer incorrectly measures blood pressure

Before saying that the tonometer measures pressure incorrectly, it is necessary to determine the measurement errors and the factors that increase them.

Everyone knows that the vast majority of modern blood pressure monitors work according to which the World Health Organization has even recognized as officially recommended. This indirect measurement method has some error, determined by the elasticity of the walls of arteries and soft tissues, the amplitude and shape of the pulse wave, and other factors that are different for each person.

If we refuse rounding and accurately use the pressure division value, then we will see the difference between adjacent measurements and when using a mechanical tonometer. Numerous experiments have shown that the error of the N. S. Korotkov tone method is usually found within ±5-7 mm Hg. Art.

The error of manual tonometers consists of three components: the error of the method, the accuracy of the manometer and the errors in determining the moment of reading the readings. It turns out that the value of the error in measuring blood pressure can reach up to 15 mm Hg. st . This must be taken into account before taking medications to normalize pressure.

To be sure of the readings of the tonometer, metrologists and doctors advise taking several measurements with a break between them of at least 3-5 minutes. Approximately in such a time, the diameter of the cross-section of the vessels is restored, which helps to improve the accuracy of measurements.

From the point of view of electronics, it's over, there may also be reasons for the increase in measurement errors. The pressure sensor and the microcontroller are responsible for this. Less commonly, there may be problems with firmware and supply voltage.

5th place - malfunctions of the tonometer electronics

Before repairing the tonometer, it is necessary to carefully inspect the printed circuit board for microcracks and poor soldering. Solder suspicious places, and check suspicious radio elements or replace them with similar ones.

After turning on the tonometer, you must immediately check the supply voltage at the control points on the board or on the contacts of the voltage converters.

Often there is a malfunction in the form of excessive consumption from. This malfunction manifests itself in the form of a short battery life. To find a board element that draws an increased current, you can use the tactile method - touch all microchips to find the hottest one. Such microcircuits need to be soldered or replaced.

If the tonometer on the display gives an incomprehensible error, then with a high probability this is also an electronics problem. In this case, you need to study the principle of operation of the tonometer and sequentially check all the elements of the circuit.

Sometimes it happens that wedge compressor tonometer - when the device is turned on, the compressor does not even twitch and the display shows an error with some number or a general error. Sometimes the jamming of the tonometer compressor is helped by disassembling it and turning the anchor around the axis. Compressor wedge can occur due to wear of mechanical parts or dust ingress. With this option, it is necessary to clean the inside of the compressor and apply inside.

Why does the tonometer show different pressure? This is often asked by users when buying a new electronic device. And it also happens that it shows different blood pressure (BP), if you measure it several times in a row. It turns out that there are many reasons for this.

Why does the tonometer show the pressure incorrectly

The device does not show pressure

Tonometer shows different pressure

The automatic blood pressure monitor responds to such factors:

Blood pressure monitors are not always accurate. This may be due to the peculiarity of the tonometer, misuse or device malfunction.

Repeated pressure measurement

If you take measurements several times in a row, the tonometer will show different pressures. This is due to the fact that after the first check, the vessel walls squeezed by the device did not have time to recover, the blood flow is still difficult. In this regard, it is recommended to re-measure only after 3-5 minutes.

“It is advisable to measure the pressure on both hands. First on one, then on the other. Then the indicator will be more accurate. It is recommended to measure the pressure three times, and the highest reading is considered true pressure, ”says doctor of medical sciences, professor of Russian National Research Medical University named after N.I. N.I. Pirogova, therapist Alexander Karabinenko.

Feature of the tonometer

Tonometers for home use are mechanical, mercury or electronic. “There are many cases when the tonometer shows the pressure incorrectly. Firstly, it may be an incorrectly applied cuff, insufficiently inflated air. If this is a membrane-pointer tonometer, then there may be a failure of the arrow, if mercury, then poor filling of the mercury reservoir. Electronic blood pressure monitors generally show pressure with an error of plus or minus 15 points of mercury,” says Karabinenko.

Failure to follow instructions

Incorrect readings can be obtained if you measure pressure without following the rules listed in the tonometer user manual. It is important to put on the cuff correctly, it should be located 1-2 cm above the elbow and fit snugly against the skin. If this is not done, it will either give a measurement error or incorrect results. Also, it must be suitable in size, otherwise, if the cuff is small, the pressure measurement result will be overestimated, and if it is too large, it will be underestimated.

The indicators will also be affected by the position in which the person measures the pressure, and his condition. During measurements, it is better to be silent and try not to move. The arm on which the cuff is located should lie on the armrest. If it hangs along the body or you are forced to keep it on weight, the indicator blood pressure may be several points higher.

“It is correct to measure the pressure while lying down or sitting, but completely relaxed, without putting one foot on the other. If a person sits cross-legged, then the pressure rises by 10-15 millimeters of mercury,” says Karabinenko.