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Monitoring Blood Pressure

When should I have my blood pressure checked?

Because high blood pressure very rarely has any symptoms, there is nothing to tell you that anything is wrong. 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 five 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. Often you will have your blood pressure closely monitored over a short period of time before any treatment is started. You may be asked to have your blood pressure rechecked on at least two further occasions, usually about a month apart.

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.


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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.


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Getting an accurate reading

Some people suffer from a 'white coat effect' where their blood pressure rises at the thought of having their blood pressure taken.

If you are due to have your blood pressure taken:

  • Remember to tell the person taking your blood pressure about any drugs you are taking
  • 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

Sometimes your doctor may want you to monitor your blood pressure at home over a period of time. This can be either by home monitoring or by 24–hour ambulatory monitoring. Both these methods tend to produce lower levels than in a clinic setting.


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Home monitoring

Home monitors allow you to measure your blood pressure yourself. The advantages of home monitoring 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 monitoring: Things to remember

Before

  • If you have high blood pressure talk to your doctor / nurse before you start monitoring your blood pressure at home. It's helpful to know how often to check it and what your baseline 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

  • Home monitor devices are not available on the NHS so you will have to buy your own. They vary in price so shop around before you buy. 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.

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.
  • Take readings at the same time each day. 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.
  • Keep a note of your results. Don't round measurements up or down.
  • 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.
  • 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. Most 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.

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Ambulatory (24hr) monitoring

Ambulatory monitoring 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 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. 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.

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


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© Chest Heart & Stroke Scotland 2012 | Page last updated on Monday 20th June, 2011