Blood Pressure Information
What is blood pressure?
Blood pressure is the pressure of the blood in the arteries as the heart pumps it around the body.
How is blood pressure measured?
Blood pressure is usually measured by wrapping an inflatable pressure bag around the upper arm. The bag is connected to a mercury ( aneroid ) or digital pressure-measuring device. The entire instrument is called a sphygmomanometer (sfig-mo-mah-nom-eh-ter).
Blood pressure is recorded as two numbers, for example 120 over 80 (120/80). The higher number indicates the pressure in the arteries as the heart squeezes blood out during each beat. It is called the systolic blood pressure. The lower number indicates the pressure as the heart relaxes before the next beat. It is called the diastolic blood pressure. Blood pressure is measured in millimetres of mercury (mmHg).
It is best to measure blood pressure when you are relaxed and sitting or lying down.
Blood pressure varies
Blood pressure does not stay the same all the time. It is always changing to meet your body’s needs.
If a reading is high, your doctor will probably measure your blood pressure again on several occasions to confirm the level. Your doctor may also recommend that you measure your blood pressure at home or have a 24-hour recording with a portable monitoring device, particularly if he or she suspects that coming to the clinic makes your blood pressure rise.
You can read more about measuring your own blood pressure in our information sheet Self-measurement of blood pressure
What is high blood pressure?
There is no firm rule about what defines high blood pressure. Your risk of heart, stroke and blood vessel disease increases as your blood pressure increases, and for most people, the lower the blood pressure the better. However, the following figures are a useful guide.
Normal blood pressure:
Generally less than 120/80 mmHg (i.e. systolic blood pressure less than 120 and diastolic blood pressure less than 80 mmHg). This is a guide only.
Normal to high blood pressure:
Between 120/80 and 140/90 mmHg. High blood pressure: 140/90 mmHg or higher. If your blood pressure is 180/110 mmHg or higher, you have very high blood pressure.
Note: The word hypertension is the medical term for high blood pressure. Hypertension does not mean nervous tension.
Why does blood pressure matter?
If your blood pressure remains high, it can lead to serious problems such as a heart attack, a stroke, heart failure or kidney disease. High blood pressure usually does not give warning signs. You can have high blood pressure and feel perfectly well. The only way to find out if your blood pressure is high is by having it checked regularly by your doctor.
The following factors increase the risks of serious problems associated with high blood pressure:
- Having high blood cholesterol
- Being overweight
What can I do if I have high blood pressure?
Your doctor is likely to measure your blood pressure several times on several occasions to confirm the diagnosis of high blood pressure. He or she may recommend that you do a test that measures your blood pressure over a 24-hour period, or that you measure your own blood pressure at home.
Your lifestyle is very important in helping you to control high blood pressure and its associated risks. Your doctor will probably advise you to:
- Be smoke-free (for information on quitting smoking, call the Quitline on 13 QUIT)
- Reduce your salt intake
- Achieve and maintain a healthy body weight
- Limit your alcohol intake to no more than two drinks per day (for men), or one drink per day (for women)
- Undertake regular physical activity.
Note: some specific types of exercises should be avoided by people with high blood pressure. These include body presses and lifting heavy weights.
Many people with high blood pressure will need to take medicines for the long-term that help to lower it. It is important that you take any blood pressure medicine exactly as it is prescribed. Don t stop taking it or change the dose without talking to your doctor first.
Normal blood pressure (less than 120/80 mmHg)
There are several ways that you can help to keep your blood pressure under control and reduce the risk of heart disease.
Have your blood pressure checked regularly, as part of an assessment of your overall risk of heart, stroke and blood vessel disease. The higher your risk, the more often that you should have these checks.
- Be smoke-free.
- Limit your alcohol intake.
- Achieve and maintain a healthy body weight.
- Be active every day accumulate 30 minutes or more of moderate physical activity on all or most days of the week. Try walking, cycling or any physical activity that you enjoy.
- Enjoy healthy eating. Choose mainly plant-based foods, such as vegetables, fruits and legumes (dried peas, dried beans and lentils), and grain-based foods (preferably wholegrain), such as bread, pasta, noodles and rice. Consume moderate amounts of lean meats, poultry, fish and reduced fat dairy products, and moderate amounts of polyunsaturated or monounsaturated fat.
© 2008 National Heart Foundation of Australia ABN 98 008 419 761
Self-measurement of blood pressure
Advantages of measuring your blood pressure at home
Blood pressure changes from moment to moment. Some of the things that can affect blood pressure are body position, emotional state, physical activity and sleep. If you have high blood pressure, altering your lifestyle may be all that is required to lower it. In other cases, you may also need to take one or more medicines.
Measuring your blood pressure at home and/or at work, with your own equipment, gives your doctor a guide to what your blood pressure is outside the clinic during your usual activities. It will also help your doctor to know whether any prescribed treatment is working.
Taking your blood pressure at home will give you a better understanding of your condition and will help you to be more actively involved in your own management.
How often should I measure my blood pressure?
This depends on your condition and treatment, and on what your doctor thinks is most relevant for you.
Typically, over the course of a week, you may be asked to measure your blood pressure first thing in the morning, two to four hours after taking your blood pressure medicine, and just before going to bed.
Once your doctor is happy with your blood pressure levels, you should take regular readings about two to three times a week. This will help you to keep up your skills in taking accurate readings. Your doctor may also ask that you take your blood pressure while lying down and/or standing.
Your blood pressure chart should be taken to your doctor at each visit. For some people who have high blood pressure readings at the clinic, your doctor may need your own recordings to help guide treatment decisions.