What is blood pressure and how is it measured? – InformedHealth.org

Created: June 24, 2010; Last Update: May 23, 2019; Next update: 2022.

The heart supplies the organs and tissues of the body with blood. With every beat, it pumps blood into the large blood vessels of the circulatory system. As the blood moves around the body, it puts pressure on the walls of the vessels. Blood pressure readings are made up of two values:

• Systolic blood pressure is the pressure when the heart beats – while the heart muscle is contracting (squeezing) and pumping oxygen-rich blood into the blood vessels.

• Diastolic blood pressure is the pressure on the blood vessels when the heart muscle relaxes. The diastolic pressure is always lower than the systolic pressure.

Blood pressure is measured in units of millimeters of mercury (mmHg). The readings are always given in pairs, with the upper (systolic) value first, followed by the lower (diastolic) value.

So someone who has a reading of 132/88 mmHg (often spoken “132 over 88”) has a

• systolic blood pressure of 132 mmHg, and a

• diastolic blood pressure of 88 mmHg.

What is normal blood pressure, and when is blood pressure considered to be high?

Blood pressure is always measured on a number of different days and when you are at rest. If several of these measurements are too high, you are said to have high blood pressure, even if only one of the two – either the systolic or the diastolic one – is high. The medical term for high blood pressure is hypertension. In adults, blood pressure is considered to be normal under a systolic value of 140 mmHg and under a diastolic value of 90 mmHg.

When taking your blood pressure for the first time, it makes sense to measure the blood pressure in both arms, because it’s sometimes high on only one side. The values that are higher are always the ones used for assessing blood pressure. After that it is enough to measure the blood pressure only in the arm that produced the higher reading. A person is considered to have high blood pressure if the systolic value is over 140 mmHg, the diastolic value is over 90 mmHg, or if both are higher than these readings.

High blood pressure itself usually goes unnoticed. Only if it is extremely high can it sometimes result in symptoms like dizziness or trouble seeing. Over the long term, high blood pressure increases your risk of cardiovascular problems like heart attacks, strokes, and heart and kidney failure. So if you or your doctor think you have high blood pressure, it’s important to have your blood pressure checked regularly. If the readings are repeatedly too high, there are several different ways of lowering your blood pressure and decreasing the risk of long-term health consequences.

Table: Normal and high blood pressure readings

How is blood pressure measured?

It’s important to measure blood pressure more than once because it fluctuates over the course of the day. It can also change due to things like physical exertion, stress, pain, or extreme heat or cold. But this kind of increase in blood pressure is only temporary and it soon returns to normal.

So, if blood pressure is measured just once and found to be high, it doesn’t necessarily mean that it’s always too high. A blood pressure reading taken at the doctor’s office can also be misleading: Going to the doctor makes some people so nervous that their blood pressure goes up.

So to get reliable readings, blood pressure is measured on several different days and while you are resting. This means sitting down and relaxing on a chair, and waiting about three minutes before taking a measurement so that your circulatory system comes to rest. The upper arm that is being used for the measurement should rest on a table, at about the same height as the heart, while the reading is being done.

You can measure your blood pressure on your own using a digital blood pressure monitor for automated readings or an instrument called a sphygmomanometer for manual readings.

Digital blood pressure monitors

Digital blood pressure monitors are often used on the wrist, but they can also be placed on the finger or upper arm and are activated simply by pressing a button. They read the blood pressure automatically based on variations in the volume of blood in the arteries. When taking blood pressure measurements on the wrist, it’s important to keep the hand level with the heart. Otherwise it can affect the readings.

Digital meters can sometimes be inaccurate and produce unreliable readings anyway – especially in people with certain heart rhythm problems or arteries that have hardened due to arteriosclerosis.

Measuring blood pressure with a sphygmomanometer

A sphygmomanometer has three parts:

• a cuff that can be inflated with air,

• a pressure meter (manometer) for measuring air pressure in the cuff, and

• a stethoscope for listening to the sound the blood makes as it flows through the brachial artery (the major artery found in your upper arm).

The scale of the pressure meter ranges from 0 to 300 mmHg. The pressure meter has a rubber pump on it for inflating the cuff and a button for letting the air out.

To measure blood pressure, the cuff is placed around the bare and stretched out upper arm, and inflated until no blood can flow through the brachial artery. Then the air is slowly let out of the cuff.

As soon as the air pressure in the cuff falls below the systolic blood pressure in the brachial artery, blood will start to flow through the arm once again. This creates a pounding sound when the arteries close again and the walls of the vessels hit each other after a heart beat. The sound can be heard by placing the stethoscope close to the elbow. Right when you start to hear this pounding for the first time you can read your systolic blood pressure off the pressure meter.

The pounding sound stops when the air pressure in the cuff falls below the diastolic blood pressure in the brachial artery. Then the blood vessels remain open. Right when the pounding stops, you can read the diastolic blood pressure off the pressure meter.

Where can I learn how to take my blood pressure myself?

In Germany and other countries, people with high blood pressure can attend patient education courses that teach a number of things, including how to measure your blood pressure. As part of specialized disease management programs (DMPs) for people who have narrow coronary arteries (coronary artery disease, CAD), statutory health insurers offer additional healthcare services. These include patient education about high blood pressure. Some doctor’s practices don’t offer these courses, though.

What is ambulatory blood pressure monitoring?

If a doctor recommends ambulatory blood pressure monitoring, you will need to wear a blood pressure cuff for 24 hours. It’s connected to a small, portable measuring device that automatically measures your blood pressure at set times and records the readings.

Ambulatory blood pressure monitoring is used, for example, to see whether blood pressure levels vary greatly over the course of the day and night or whether they are constantly elevated. During those 24 hours, you can do all of the usual things you would otherwise do over the course of the day. If you are especially active at certain times, you can make a note in a diary. Then the doctor has a better idea of how to interpret the recorded values when evaluating them.

Sources

• Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J. Harrison’s Principles of Internal Medicine. New York: McGraw-Hill; 2015.

• Pschyrembel. Klinisches Wörterbuch. Berlin: De Gruyter; 2017.

• Stierle U (Ed). Klinikleitfaden Kardiologie. Munich: Urban und Fischer; 2017.

• IQWiG health information is written with the aim of helping
  people understand the advantages and disadvantages of the main treatment options and health
  care services.

  Because IQWiG is a German institute, some of the information provided here is specific to the
  German health care system. The suitability of any of the described options in an individual
  case can be determined by talking to a doctor. We do not offer individual consultations.

  Our information is based on the results of good-quality studies. It is written by a
  team of
  health care professionals, scientists and editors, and reviewed by external experts. You can
  find a detailed description of how our health information is produced and updated in
  our methods.

How to accurately measure blood pressure at home

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High blood pressure is one of the top risk factors for heart attack and stroke. It’s also common among people who develop severe COVID-19 symptoms.

So, with more people at home practicing social distancing and with fewer chances to check blood pressure at public pharmacy machines or doctor visits, it’s more important than ever to know how to do it at home.

How do I select a home blood pressure monitor?

“The readings you get at home are really important, because they reflect the pressure your heart is facing on a day-to-day basis,” said Dr. Michael Hochman, a doctor of internal medicine at Keck Medicine of the University of Southern California.

A list of validated home monitors, the first in the United States and commissioned to meet the American Medical Association’s criteria, is available at validateBP.org. The Advancement of Medical Instrumentation, the British Hypertension Society and the European Society of Hypertension also certify devices.

The device should measure blood pressure on the upper arm, which produce a more reliable result than those that measure from the wrist.

Many devices are automated. Simply put on the cuff and press a button. The results are displayed digitally.

Some will store readings, calculate an average blood pressure over time, or even transmit them to your doctor.

“When blood pressure monitors cannot transmit readings to a patient’s doctor, the next best thing is to have a device that stores the blood pressure readings,” said Paul Muntner, professor of epidemiology and associate dean for research at the University of Alabama at Birmingham.

Your health care provider should check the device about once a year to ensure its accuracy.

How do I get the most accurate measurement?

Do not smoke, drink caffeinated beverages or exercise within 30 minutes before measuring your blood pressure. It’s important to use a cuff that fits your arm. Cuffs that are too small can artificially raise your blood pressure reading.

With the cuff on your bare arm, sit in an upright position with back supported, feet flat on the floor and your arm supported at heart level. Make sure the bottom of the cuff is directly above the bend of the elbow. Relax for about five minutes before taking a measurement. Resist the urge to talk or look at a cellphone.

Also, make sure your bladder is empty, as a full one can temporarily raise blood pressure.

Some medications, including over-the-counter pain relievers called NSAIDs and common decongestants, can elevate blood pressure. Alcohol, caffeine, smoking, salt intake and stress can, too.

Muntner recommended people check their blood pressure at the same time each day, such as twice in the morning and twice in the evening for one week, then talk with their doctor about the results.

“Blood pressure fluctuates a lot, so a patient shouldn’t worry about one high reading,” Muntner said. “If the average over a full week is high, there’s reason for people to talk to their doctors. If not, people should continue practicing heart-healthy behaviors and check their BP in the future.”

What is the ideal blood pressure?

The device will give you a systolic number (upper) – the pressure against your artery walls when your heart beats – and a diastolic number (lower) – the pressure between beats.

For normal readings of less than 120/80, Muntner said it’s not necessary to check blood pressure again for at least six months.

If the top number is 130 or greater, or the bottom number is 80 or greater, Muntner recommended talking with your doctor about your overall risk for heart attack and stroke.

“If someone is at higher risk – for example, they smoke or have diabetes – then they should be started on blood pressure-lowering medication,” he said.

“If it’s very high, 180 or higher (over) 110 or higher, you should call your doctor right away. The longer your blood pressure is high, the more you are at risk for heart attack and stroke.”

There are many ways to lower blood pressure, including medication, getting more exercise, eating plenty of fruits and vegetables, not smoking, reducing salt and alcohol consumption, lowering stress and losing weight.

“For some people, it may be easier to reduce the amount of salt they eat. For others, it may be easier to do a little physical activity,” Muntner said. “The important thing is to do the things that work for each individual.”

If you have questions or comments about this story, please email [email protected].

prognosis, treatment, symptoms in the international clinic Medica24

In order for the tonometer to show the exact value of blood pressure, the measurement must be carried out correctly. With automatic devices (read the article about the types of blood pressure monitors), everything is relatively simple: just put a cuff on your shoulder or wrist, turn on the device, and then it will do all the work itself.

In this article you will find detailed step-by-step instructions for using mechanical and semi-automatic blood pressure monitors.

At home, you can ask a family member to take your blood pressure, or you can do it yourself. It is better to measure on the left hand – it will be more convenient for you to hold the pear and pump air with your right.

Getting ready to take your blood pressure

It’s best to take your blood pressure in a quiet room where no one will disturb you. Sit on a chair next to the table, relax. Your back should rest against the back of the chair. Do not sit cross-legged.

Place the arm on which you will measure the pressure on the table, palm up, so that it is approximately at the level of the heart. Sit like this for 5-10 minutes, relax.

Place your index and middle fingers in the crook of your elbow and feel for a pulse. This will help you correctly position the stethoscope head. If you can’t find a pulse, it’s okay, just place the head of the phonendoscope in the crook of your elbow.

Place the blood pressure cuff on your arm. Its lower edge should be 2.5-3 cm above the bend of the elbow. It can be marked with a special mark that will help you position it correctly. If the head of the phonendoscope is built into the cuff, place it approximately in the middle of the elbow bend.

How to measure blood pressure with a mechanical sphygmomanometer?

Take pressure gauge (instrument with arrow and numbers) in your left hand (the one on which you measure the pressure), the bulb in your right. Close the pear valve and inflate the cuff until the pressure gauge needle is on the number, which is 30 mm. rt. Art. higher than expected blood pressure.

Start to slowly deflate the cuff. At this time, carefully look at the arrow of the manometer.

When you hear the first beat in the phonendoscope, the needle on the pressure gauge will show the “upper” ( systolic ) blood pressure. From that moment on, she will begin to move not smoothly, but as if in jolts.

Continue to bleed air slowly and watch the pressure gauge. When you stop hearing the beats, the arrow will show the “lower” (diastolic) blood pressure. After that, you can deflate all the air and remove the cuff. The measurement is finished.

If you have never used a mechanical blood pressure monitor before, you may not be able to measure your blood pressure the first time. You need to learn how to slowly release the air and “catch” the arrow. If you deflate too quickly and hear nothing, don’t immediately re-inflate the cuff. Release the air and wait a couple of minutes.

How to measure blood pressure with a semi-automatic sphygmomanometer?

Take the bulb in your right hand (the one you don’t use to measure pressure) and turn on the instrument. Usually, the display shows the last measurement data first, then zeros. This means that the device is ready for use. Some models signal readiness with a squeak or other sound.

Inflate the cuff by squeezing the bulb. The numbers on the display will start to change, the device will notify you with a sound when you need to stop (if this function is not provided, then inflate until the numbers on the display show a value that exceeds the estimated pressure by 30 mmHg).

The device will begin to bleed air and measure pressure by itself. At this time, he will make short rhythmic sounds. A long beep or beep will indicate that the measurement is over. Your blood pressure value will appear on the display (most models show the pulse rate at the same time).

You can deflate and remove the cuff.

Be sure to record the measurement results. Well, if you get a separate notebook for this. Some blood pressure monitors can store numbers in their memory.

By constantly keeping records, you will be able to track your pressure in dynamics, show the results of the latest measurements to the doctor.

How to measure pressure with a manual blood pressure monitor

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How to measure pressure with a manual tonometer

A manual tonometer is easy to use, costs much less than electronic analogues and is durable. At the first use, a person is faced with the fact that he does not know how to use it correctly. Let’s figure out how to measure pressure with a manual sphygmomanometer.

Measure the pressure correctly

An hour before measuring pressure, it is not recommended to smoke, drink alcohol, coffee and strong tea. Do not measure blood pressure immediately after exercise.

To measure pressure with a mechanical sphygmomanometer, follow these rules:

• Sit comfortably with your back against the back of a chair.
• Place your arm on the table and put the blood pressure cuff on it. Remember, in order to correctly measure the pressure with a tonometer, the cuff should be placed at the level of the heart and slightly above the elbow bend (1.5-2 cm).
• Insert the phonendoscope into the ears and press against the brachial artery in the region of the antecubital fossa.
• Check the bulb valve of the tonometer, it must be closed.
• While squeezing and unclenching the rubber bulb, inflate the cuff to 20-30 mm above normal systolic.
• Gradually loosen the valve to bleed the air. To correctly measure the pressure with a tonometer, carefully follow the arrow and listen to the pulse: remember at which digit you heard the first beat of the pulse (this is systolic, upper pressure) and at which digit the beats stopped (diastolic, lower pressure).

Now you know how to measure pressure with a manual sphygmomanometer. Did everyone understand? Try to measure the pressure with a mechanical sphygmomanometer on your own.

When is the best time to take blood pressure

If the doctor has prescribed regular measurements, keep a notebook and write down the indicators there. It is better to do this every day at about the same time and at least twice (for example, in the morning and in the evening).

If you have arrhythmia, it is advisable to carry out serial measurements – double-check and write down the numbers 3 times, but with breaks of at least 2-3 minutes.