Measuring Your Blood Pressure at Home

Measuring your blood pressure needs to give accurate readings if it is to be worthwhile.  You may have been advised to measure your blood pressure at home in order to get a more accurate record or your readings. 

The following information is from the Blood Pressure Association's fact sheet "Measuring Your Blood Pressure at Home"

Many people with high blood pressure measure their blood pressure at home, in between visits to their doctor or nurse. Some people may also be asked by their doctor or nurse to take measurements at home for a short period of time to find out whether they have high blood pressure or not.

There is a wide range of blood pressure monitors available to buy and choosing the right one is important to make sure you get accurate readings. It is also important that you know how to take readings, what to do with the results and what might affect the readings. 

Machines for measuring your blood pressure are not available on the NHS so you will have to buy your own. They range in price from about £30 to £150. Many of the leading brands and top models are available at very discounted prices online on web sites such as Medisave

Why do people monitor their blood pressure at home?

Some people are asked by their doctor or nurse to measure their blood pressure at home for a short period of time, usually two weeks, to find out what it is like away from the surgery or clinic. Sometimes your blood pressure is only raised when taken in a clinical or medical environment, such as your doctor’s surgery. This is called white coat hypertension and can be caused by feeling anxious, or by being in a busy or noisy environment. This can affect readings by as much as 30mmHg (systolic readings). 

Blood pressure readings taken at home are often lower than those taken at a doctor’s surgery, whether a doctor or a nurse takes them. Readings taken away from the clinic are now seen to give a more accurate picture of your blood pressure.

To be sure that you have high blood pressure your doctor needs more than one reading, and home measurements can be a good way of finding out what your blood pressure is like when you are relaxed and going about your daily life. The other way of doing this is by having 24-hour (ambulatory) blood pressure monitoring done. 

Monitoring blood pressure over a period of time at home can also provide your doctor or nurse with more information about how well your treatment is working and how you respond to medications. Home blood pressure monitoring can also be useful for people who have high blood pressure and who are taking medications as it can mean that you are able to cut down on the number of visits to your surgery for checks. 

Many people enjoy measuring their own blood pressure and monitoring their condition because it helps them to feel in control of their high blood pressure and health, and involves them in making decisions about their treatment.

Is monitoring my blood pressure at home the right thing for me?

Most people feel more in control of their condition if they take and monitor their blood pressure at home. Once they are familiar with how to take their readings and are comfortable doing so, they make it part of their daily routine. Doing so helps to show that their medicines and lifestyle changes are working and they understand much more about their condition. However, taking readings at home is not for everyone. It makes some people more anxious. If this happens, talk to your doctor and see if you are taking the readings too frequently or if you should stop doing so. Generally speaking, it is not necessary in the long term to take readings more than once a week unless your doctor has specifically asked you to do so.

There are a few physical conditions that can make monitoring at home difficult. If you have an irregular heart rate, such as atrial fibrillation, then you may not be able to get a good reading – a digital machine may read ‘error’. If you have difficulty bending or moving your arms you may find putting on the cuff and taking a reading without help difficult. If you have lymphoedema, or have had a lymphectomy, then you should not have a blood pressure reading taken on the affected arm, as the pressure can cause or make lymphoedema worse.

Before you buy a blood pressure monitor

Talk to your doctor or your nurse about monitoring at home. Many health professionals actively encourage people with high blood pressure to take and then monitor their readings themselves. You can discuss how often you need to take readings and what contact you should have with the surgery while monitoring your blood pressure. You can work together to ensure you are well informed and that your blood pressure is being treated effectively. A few doctors may be unhappy about you monitoring at home. If this is the case, talk to them about your reasons for wanting to monitor at home. 

Work out some guidelines with your doctor or nurse. Agree how often you should take your readings and at what time of day, as well as when you need to go back to the surgery. For example if your readings go above a certain level, how and when will you let your doctor or nurse know.

Choosing an accurate machine 

Machines for measuring your blood pressure are not available on the NHS so you will have to buy your own. They range in price from about £30 to £150. Many of the leading brands and top models are available at very discounted prices online on web sites such as Medisave

Most people who measure at home use an automatic or semi-automatic machine. These are simple to use and will often store your readings in their memory and provide you with a printout. Automatic machines inflate and deflate the cuff for you. With semi-automatic machines you will need to inflate the cuff by hand.

Having a consistently accurate reading that you can trust is important, not only for you when you are testing at home but also for your health professional. Inaccurate readings can lead to misdiagnosis, and can mean the difference between having treatment or not. Therefore the first priority when buying a monitor is to choose one that you know is accurate. So:

· Choose a machine that measures from the top of the arm, rather than the wrist or the finger. Finger monitors will not give accurate readings and wrist monitors are also less likely than upper arm monitors to give an accurate reading. 

· Choose a monitor that has passed independent testing for accuracy. When you look at blood pressure machines, you should find they carry a “CE” marking on their packaging. However, although monitors marked with “CE” show that they have undergone some testing, this is not a reflection of their accuracy. The British Hypertension Society (BHS) has therefore compiled a list of accurate monitors as a guide for home users. The monitors on this list have been independently tested to a protocol set by the British Hypertension Society or the European Society of Hypertension, and have been found to be accurate. The BHS list is compiled from research papers and not direct testing, but you may find it a useful guide when you buy a monitor. All the monitors on this list measure blood pressure from the upper arm (upper arm monitor).

This list is regularly updated, so do check the web site for the latest information.

Using the right size of cuff is important for an accurate reading. Four out of every five people are able to use the standard size cuff that comes with the monitor and get an accurate reading. However, some people have very thin or very large arms and a standard size cuff may produce inaccurate readings. If the cuff is too small the reading may be falsely high and if it is too big the reading may be falsely low. If you have any doubts, ask the manufacturer of your monitor about the cuff sizes they have available and check with your doctor or nurse that you are using the right one.

It is now possible to buy monitors that connect to your computer to allow you to use a computer programme to record readings. A and D instruments also make a version of the UA-767, for use by people who are visually impaired, which ‘talks’ to you. Visit Medisave who stock a wide range of machines.

Taking readings - When and how often should I take readings?

When and how often you take readings will depend on your blood pressure. Some people may need to take a number of readings over a short period of time, others will need to take a reading once a week. Your doctor or nurse will be able to advise you. If you take readings less than once a week you may be likely to forget, so try and make your readings part of your routine. A few people find that there is a difference between readings taken on days when they work and days when they do not, so try taking readings during these times as well.

When you first start taking readings at home discount the first day’s measurements. They may not be accurate because you are unfamiliar with the monitor and could be anxious. It is useful to take readings at the same time of day so that you are consistent and are comparing ‘like with like’.

Which arm should I use to measure blood pressure?

There can be a difference between the readings on each arm. When you first use the monitor take a reading on both the left and right arm and then in future use whichever arm gives you the higher reading. Always use the same arm for readings. If you find that the difference between the readings on either arm is greater than 20mmHg systolic (top number) or 10mmHg diastolic (bottom number) talk to you doctor or nurse about your readings. 

How do I take a blood pressure reading?

· Wear a short sleeved T-shirt or loose fitting clothing so that the sleeve can be rolled up comfortably
· Before taking readings rest for five minutes. You should be sitting down, preferably at a desk or a table, in a quiet place, with your arm resting on a firm surface. It is very important that your arm is supported so that the cuff around the arm is at the same level as your heart. You may need to support your arm with books to make sure it is at the correct height. Ensure that the arm is totally relaxed and not tensed
· The deflated cuff needs to be tight, but not too tight. You should be able to insert two fingers between it and the skin
· If you are using a machine that needs you to set the systolic level for the cuff inflation, choose a setting that is at least 20mmHg above your last reading. For example, if your last systolic reading was 153, set the machine to inflate to 180.
· Start the machine – keep still and silent whilst the reading is taken. Moving and talking can affect the reading
· Take two or three readings each about two minutes apart. If you take two readings disregard the first and use the second, if you take three readings disregard the first and take an average of the second and third
· Some people find that when they take two or three readings the first is always highest and then the readings become lower each time they take them. If this is the case keep taking readings until they level out and then use this as your reading
· Record the reading either in the memory of the machine or on computer or paper. Make sure you keep accurate records – some people are tempted to round the numbers up or down, or to record a lower blood pressure. This can affect your treatment and therefore your long-term risk of stroke and heart attack. Also record any medications you have taken and when, and any other information such as whether you have just eaten or exercised.

What is my ideal level of blood pressure?

The aim of treatment for high blood pressure is to reduce it, when measured by your doctor or nurse, to below 140/85mmHg. When it is measured in a clinic, particularly by a doctor or nurse, it may be higher than when you are more relaxed at home. It is therefore important that with home measurements they should at least be below 140/85mmHg and preferably below 130/80mmHg. This can be hard to achieve for some people and your doctor or nurse may set you a different target.

What do I do if my blood pressure readings start to go up?

As blood pressure varies in everybody by quite a large amount, you may get unexpected ‘one off’ high readings, so always repeat the measurement again at another time. However, if you find that on repeated measurement your blood pressure over a period of time is higher than usual go and see your doctor or nurse, taking details of the measurements with you. The important readings are the averages over a period of time and not individual readings.

Is there anything that might affect my blood pressure readings?

There are several factors that can make your blood pressure rise temporarily; exercise, alcohol, caffeine, tobacco, a full bladder, talking, anxiety, excitement and pain are just a few. It is worth recording what you have been doing before a reading, as it will act as a guide for you and your doctor or nurse.

Where can I buy an accurate blood Pressure Monitor? Medisave is a leading supplier of medical equipement to health professionals and the public in the UK.  They are the only UK stockist of all makes of British Hypertension Society validated machines from Microlife, Omron and A and D Instuments.  Make an informed purchase and trust machines that are considered accurate by the British Hypertension Society.  US visitors can find similar monitors available here

A new web log which covers a wide range of topics about blood pressure is at Blood Pressure Information Blogspot.

watch the video "How to Measure Blood Pressure"

In 2007 we were delighted that Ellie Precious kindly donated her time and online PR experience to help raise awareness of the importance of blood pressure monitoring.