How is blood pressure determined: What is blood pressure and how is it measured? – InformedHealth.org
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
| Normal blood pressure | systolic under 140 mmHg and diastolic under 90 mmHg |
| High blood pressure | systolic over 140 mmHg and/or diastolic over 90 mmHg |
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.
The suitability of any of the described options in an individualWhat 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
| Normal blood pressure | systolic under 140 mmHg and diastolic under 90 mmHg |
| High blood pressure | systolic over 140 mmHg and/or diastolic over 90 mmHg |
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.
You canRules and techniques for measuring blood pressure
Rules and techniques for measuring blood pressure. Tonometers for home use.
It should be remembered that at present, special attention is paid to measuring blood pressure (BP) at home. It has been proven that self-monitoring of blood pressure and keeping a diary of hypertension help to increase the patient’s motivation for the treatment of hypertension, increase the effectiveness of treatment by 15-20%. When visiting the attending physician, specialist consultant, you must bring diary entries with you.
When measuring blood pressure with any tonometer, in order to improve the accuracy of the results, a number of conditions must be observed.
- measurement of blood pressure should be carried out in a sitting position;
- It is necessary to provide emphasis on the back of the chair, relax the legs;
- the measurement is made after a 5-minute rest;
- the arm to be measured must lie on the table and be at the level of the heart;
- the measurement is carried out on the arm on which the pressure is higher;
- do not talk while measuring blood pressure;
- for 1-1. 5 hours you need to exclude eating and smoking;
- you need to have a cuff of the required size, which is required to be applied to the bare shoulder;
- the lower edge of the cuff is located 1-2 cm above the elbow;
- it is recommended to measure blood pressure twice with a break of 3-5 minutes.
5 hours you need to exclude eating and smoking;Measurement of blood pressure by auscultatory method (Korotkoff method) using a phonendoscope and listening to pulsation tones requires compliance with additional rules:
- place the head of the stethophonendoscope in the center of the antecubital fossa;
- inflate the cuff quickly enough; at the same time, the inflation level should be 20-30 mm Hg higher than the “usual” blood pressure;
- after opening the tap, the air should be bled at a speed of 2-3 mm Hg per second;
- fix the appearance of the first Korotkoff sound, which indicates systolic blood pressure;
- to fix the disappearance of Korotkoff sounds, which indicates diastolic blood pressure.
Which blood pressure monitor is recommended for measuring blood pressure at home?
The European Guidelines for the Treatment of Hypertension and the Recommendations of the Russian Society of Physicians “Prevention of Chronic Noncommunicable Diseases” (2013) recommend “… to measure blood pressure in patients automatically using various models of tonometers” . Firstly, it is these devices that provide high measurement accuracy. Secondly, due to the convenience and simplicity of the procedure for measuring blood pressure, only automatic blood pressure monitors contribute to the high motivation and commitment of the patient to the constant measurement of blood pressure and keeping a hypertension diary.
Thus, in particular, the measurement of blood pressure by the auscultatory method (Korotkov method) using a phonendoscope and listening to pulsation tones requires good hearing, experience and coordination of the “hands-eyes-ears” system.
In addition, the observance of the cuff inflation and deflation technique required for high accuracy results makes the procedure difficult for a person who does not have the skills to do so. Failure to comply with these rules leads to an error in the results when using mechanical tonometers of 10-15 mm Hg. Such an error is significant and can affect the treatment and prognosis of the disease. The use of a pear for self-pumping of air is undoubtedly associated with muscle tension in the arm, which also leads to an increase in blood pressure values. Therefore, the use of semi-automatic blood pressure monitors with an oscillometric sensor, but retaining a pear for self-inflating air, is unjustified.
The accuracy of automatic sphygmomanometers over the past decades has been repeatedly evaluated according to stringent international criteria for standardizing medical devices. This was the basis for recommending the use of automatic blood pressure monitors at home.
OMRON Blood Pressure Monitor is the #1 home blood pressure monitor.
OMRON blood pressure monitors have all the essential features that make them the #1 home blood pressure monitor. The fan-shaped cuff of the universal size of 22-42 cm, repeating the natural contour of the arm, evenly distributes air, making the measurement painless and accurate. The Intellisense intelligent system pumps air immediately, adjusting to the patient – 20-30 mm above systolic blood pressure, making measurement convenient, fast and accurate.
It should be emphasized that many models of OMRON automatic blood pressure monitors have cuff position sensors, arm movement sensors, as well as arrhythmia indicators. At the same time, only the OMRON model M6 tonometer can most accurately measure blood pressure during atrial fibrillation, which is a significant difference between this model and other tonometers, including those from other manufacturers.
OMRON, which produces highly sensitive sensors used in a wide variety of equipment, has been producing blood pressure monitors for 40 years, which are used in medicine in different countries.
These characteristics make OMRON blood pressure monitors the leader in sales in Russia over the past few years.
Based on research conducted by American and European experts, OMRON automatic blood pressure monitors have been awarded a high accuracy class (A) (European Society of Hypertension, 2013).
OMRON wrist blood pressure monitors are also recommended. These devices, first of all, are shown to people with a large shoulder volume, as well as to those who often take a tonometer on the road. Currently, there is no age limit for the use of carpal tonometers. Important! Accurate blood pressure measurement requires the most correct position of the cuff sensor at the level of the patient’s heart.
Important to know!
When measuring blood pressure with any tonometer, consecutive measurement of blood pressure with an interval of 2-3 minutes will give different values. The value of blood pressure, like all other parameters of the body, is not constant and is within the limits of physiological fluctuations.
Differences in the readings of tonometers should not be regarded as manifestations of inaccuracy or malfunction of the instruments.
Rules for measuring blood pressure – State Healthcare Institution ‘Polyclinic No. 10’
Blood pressure – measurement at home.
Many at home have a device for determining blood pressure (BP) – a tonometer. It is purchased on the recommendation of a doctor and independently to control the level of blood pressure. At the same time, not everyone uses this device correctly, which leads to a false alarm, or, on the contrary, does not allow timely detection of arterial hypertension (AH). In order for the results to be accurate, certain rules must be observed when measuring blood pressure.
Types of blood pressure monitors used at home to measure blood pressure
Blood pressure monitors For people with hypertension:
we recommend the following blood pressure monitors:
– Mechanical.
– Semi-automatic (combined).
– Automatic (electronic).
Wrist and finger instruments are used for dynamic control in sports training and the like. Their use is not recommended for patients with high blood pressure.
The most convenient to use for self-monitoring of blood pressure are automatic or semi-automatic tonometers.
Important! The results of self-measurement of pressure at home, when discussing them with a doctor, are considered an important basis for correcting medication intake. This procedure is a measure of control of the patient’s condition.
How to prepare for blood pressure measurement
In order for the tonometer readings to be reliable, the following simple rules must be followed before starting the procedure:
- Morning measurement (a particularly important indicator) is carried out after waking up, evening – at the same “fixed” time.
- Rest for 5-10 minutes before manipulation, avoiding physical exertion.
- It is not recommended to measure blood pressure immediately after a stressful situation, strong excitement – the readings will be overestimated.
- Do not eat or drink containing caffeine, do not drink alcohol, do not smoke 30 minutes before measuring blood pressure.
- The procedure should be carried out while sitting on a chair, leaning on its back. In this case, the posture should not be tense. The hand on which the measurement will be carried out is free from clothing. It is not recommended to roll up the sleeve, as it can compress the vessels, which will distort the result. Put your feet on the floor, do not cross your legs and do not throw one on top of the other – this also compresses the vessels and affects the correct readings of the device.
- Do not talk during the procedure.
- Empty the bladder before taking a measurement.
- The blood pressure cuff is put on the forearm, its lower edge should be at a distance of 1-2 cm from the elbow. The arm on which blood pressure is measured lies freely on the table, the cuff on it should be at the level of the heart.
- Manipulation can be carried out both on the right and on the left hand – there is no significant difference. However, in the case of daily control, it is advisable to take measurements on the same arm.
The arm on which blood pressure is measured lies freely on the table, the cuff on it should be at the level of the heart. Rules for measuring blood pressure with different types of tonometers
Measuring blood pressure with a mechanical tonometer
After completing all the preparatory steps, a stethoscope disc is applied to the inner bend of the elbow to monitor the heartbeat, air is pumped into the cuff to a level exceeding the usual value by 30- 40 mmHg pillar. Then the air gradually descends from the inflatable bag – approximately 4 mm Hg. columns per second. It is necessary to be careful – the first beat of the heartbeat corresponds to the upper limit of blood pressure (systolic pressure), the last beat – to the lower level (diastolic pressure).
Measurement of blood pressure with a semi-automatic device
In this case, the role of the patient using the device (or the person caring for the patient) is to inflate the cuff with a rubber bulb, and then press the button to bleed air from it. The device will perform all measurements itself. The display screen will show the results – the upper and lower levels of blood pressure. Most often, such devices also show the pulse rate.
Measurement of pressure with an automatic sphygmomanometer
The easiest way to measure. It is enough just to put the cuff on the forearm correctly and press the “Start” button. The device itself inflates the cuff and determines the level of blood pressure. The readings are shown on the display. In most cases, tonometers of this type save a history of measurements, which is useful for a correct assessment of the general condition and course of the disease. Therefore, the information from the device must be transferred to your doctor.
How to read blood pressure correctly
It is not recommended to focus on the readings of a single measurement of blood pressure, since any device, mechanical or electronic, may have an error. Important! This does not apply to cases when a person’s condition has deteriorated sharply, he feels a headache, chest pain, shortness of breath and other signs of a critical increase in pressure, which poses a serious threat to the health and life of the patient. In this case, you should call an ambulance.
So, if this is a normal pressure measurement for the purpose of monitoring the condition, it is recommended to take several measurements: 2 – when measuring with a mechanical tonometer, 3 – when using an automatic or semi-automatic device. The interval between measurements should be 0.5-2 minutes. When measuring with a mechanical tonometer, the average value of the measured values should be recorded for evaluation, when measuring with an automatic or semi-automatic device – the minimum value.