Monitoring your blood pressure

The only way to know what your blood pressure is is to have it checked

The only way to know what your blood pressure is is to have it checked

When should I have my blood pressure checked?

High blood pressure very rarely has any symptoms so the only way to know your blood pressure reading is to have it measured.

It is recommended that you should have your blood pressure checked, as part of an overall cardiovascular risk assessment, at least every 5 years if:

  • You are 40 years old or above
  • You have a close relative (parent, brother, sister or child) who has had heart disease and / or stroke illness before the age of 65 (women) or 55 (men) or has a genetic cholesterol problem (called familial hypercholesterolaemia)

You should also get your blood pressure checked if:

  • You are of Afro-Caribbean, Asian or Chinese descent
  • You are taking the contraceptive pill
  • You have diabetes
  • You are concerned about your lifestyle, e.g. being overweight, excess alcohol intake, high salt intake, high saturated fat diet, lack of exercise
  • You go to the doctor with symptoms that could be related to having untreated high blood pressure
  • You are taking any other prescribed drugs that may affect your blood pressure

A 'one off' high measurement is not enough to make a diagnosis of high blood pressure. Before any treatment is started you may have your blood pressure closely monitored by your doctor or he / she may want you to monitor your blood pressure at home over a short period of time.

If you are started on any drugs to lower your blood pressure then your doctor / nurse will monitor you closely to see how your blood pressure responds to treatment.

Does my blood pressure stay the same?

Your blood pressure fluctuates throughout the day, depending on what you are doing.

  • During physical work or exercise the muscles need a greater supply of food and oxygen. If you are working hard mentally, e.g. you are concentrating or under stress, the demand is also greater. To meet this demand, the blood flow has to be increased so your heart has to beat faster and harder and the blood pressure rises.
  • When you are asleep your blood pressure is at its lowest. Even then, there are fluctuations as you dream.
  • As well as blood pressure levels going up and down throughout the day depending on demand, there are many other things that can affect your blood pressure. Hurrying, strong emotions, pain, alcohol, some drugs (including recreational drugs such as cocaine) and even a full bladder can all result in a misleading blood pressure reading.

Getting an accurate reading

The 'white coat effect' is when your blood pressure rises at the thought of having your blood pressure taken. To prevent this:

  • Try to relax
  • Sit quietly for at least 5 minutes beforehand
  • Make sure your bladder is empty
  • Try and avoid having a heavy meal immediately before
  • Remember to tell the person taking your blood pressure about any prescribed drugs you are taking

Sometimes your doctor may want you to monitor your blood pressure at home over a period of time. This can be either by 24-hour ambulatory monitoring or by home monitoring. Both these methods tend to produce lower levels than in a clinic setting. These readings can be particularly helpful when diagnosing high blood pressure as well as monitoring your response to treatment.

Ambulatory blood pressure monitoring (ABPM)

For some people the ambulatory method can be more helpful than home or clinic measurements as it provides a full 24-hour profile.

  • ABPM involves wearing a device that automatically takes your blood pressure, at intervals over a 24-hour period, as you go about your daily activities.
  • The monitor has a cuff that is wrapped around your arm, and is connected to a small device on a belt or strap worn on your body. The device is fitted by a doctor or nurse at your clinic / hospital. Normally you will have your blood pressure monitored at 15 - 30 minute intervals during the day and 30 - 60 minute intervals at night.
Measuring your blood pressure at home tends to produce lower levels than in a clinic setting

Measuring your blood pressure at home tends to produce lower levels than in a clinic setting

These measurements can be used to work out your average day and night-time readings and so establish more accurately if your blood pressure is raised for long periods.

Home blood pressure monitoring

Home monitors allow you to measure your blood pressure yourself.

Advantages include reducing the 'white coat effect' and the ability to have several recordings over a number of days. It also allows you to become involved in your own care and management of your blood pressure.


                                          Home blood pressure monitoring: things to remember

  • If you are being treated for high blood pressure talk to your doctor / nurse before you start monitoring your blood pressure at home. It is helpful to know how often to check it and what your ideal blood pressure is.If you don't have high blood pressure you can still monitor it at home as part of a 'lifestyle checker'. Aim to check it once a week, at the same time each week.
Buying a monitor

  • When choosing a device make sure it has been 'clinically validated' and is listed by the British Hypertension Society. Ask your pharmacist for advice or contact the Blood Pressure Association.
  • Machines that measure your blood pressure on your upper arm tend to be more reliable than wrist monitors. Make sure you buy a monitor with the correct cuff size for your arm.
  • They vary in price so shop around.
Using your monitor

  • Follow the general advice above for getting an accurate reading. Avoid taking your blood pressure if you are upset, feeling stressed, have had a very busy day, have just been exercising or have recently had a cigarette.
  • Follow the advice from your doctor / nurse as to how often you should monitor your blood pressure. It is good to take readings at the same time each day.
  • Keep a note of your results.
  • Remember your readings may be lower at home than at the clinic. Look at the general trend of your blood pressure. Don't directly compare figures taken at home to those at the clinic.
  • Don't round measurements up or down.
  • Try not to worry if you get an unexpected high reading. It is normal for your blood pressure to fluctuate. Continue to monitor your blood pressure and if it continues to be high, or you feel unwell, contact your doctor or nurse.
  • Keep your monitor calibrated. To ensure accurate readings most automatic monitors need to be re-calibrated. Follow the manufacturer’s instructions as to how often this is needed (usually at least every 2 years) and where to send your monitor.
  • Don't measure your blood pressure too often. Your monitor is meant to help you feel in control of your blood pressure care; it is not meant to add to your stress levels.
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