Test Overview
A home blood pressure test allows you to keep track of your
blood pressure at home. Blood pressure is a measure of
the force of blood inside an artery. A blood pressure measurement is taken by
temporarily stopping the flow of blood in an artery (usually by inflating a
cuff around the upper arm) and then listening for the sound of the blood
beginning to flow through the artery again as air is released from the
cuff.
As blood flows through the artery, it can be heard through a
stethoscope placed on the skin over the artery. Blood
pressure is recorded as two measurements.
- The reading on the gauge when blood flow is
first heard is called the systolic pressure. Systolic
pressure represents the peak blood pressure that occurs when the heart
contracts.
- The reading on the gauge when blood flow can no longer
be heard is the diastolic pressure. Diastolic pressure
represents the lowest blood pressure that occurs when the heart relaxes between
beats.
These two pressures are expressed in millimeters of mercury
(mm Hg) because the original devices that measured blood pressure used a column
of mercury. Blood pressure measurements are recorded as systolic/diastolic (say
"systolic over diastolic"). For example, if your systolic pressure is 120 mm Hg
and your diastolic pressure is 80 mm Hg, your blood pressure is recorded as
120/80 (say "120 over 80").
Types of blood pressure monitors
The two general
types of blood pressure monitors commonly available are manual and
automatic.
Manual blood pressure monitors
Manual models are
similar to those that your doctor might use to take your blood pressure. Called
a sphygmomanometer, these devices usually include an arm cuff, a squeeze bulb
to inflate the cuff, a stethoscope or microphone, and a gauge to measure the
blood pressure.
Blood pressure is displayed on a circular dial
with a needle. As the pressure in the cuff rises, the needle moves clockwise on
the dial. As the cuff pressure falls, the needle moves counterclockwise.
Automatic (also called electronic or digital) blood pressure monitors
Electronic battery-operated monitors use a microphone to
detect blood pulsing in the artery. You do not need to listen with a
stethoscope. The cuff, which is attached to your wrist or upper arm, is
connected to an electronic monitor that automatically inflates and deflates the
cuff when you press the start button.
The type of blood pressure
monitor typically found in supermarkets, pharmacies, and shopping malls is an
electronic device.
Ambulatory blood pressure monitoring (ABPM)
Ambulatory blood pressure monitoring (ABPM) is another method that may be
ordered by your doctor if other methods do not give consistent results. It is
often used if there is a big difference between the blood pressure readings you
get at home and your readings in your doctor's office.
An ambulatory blood pressure monitor is a small device that is worn throughout the day, usually
for 24 or 48 hours. The device takes your blood pressure automatically. The device periodically inflates and takes blood pressure
measurements, which are recorded for later printout and analysis. The devices
are usually loaned by a clinic or hospital.
If you are required to use an ambulatory blood pressure monitor, keep
in mind that it is important for a health professional to properly size the
cuff, which fits around your arm. Fitting does not take long.
Why It Is Done
Home blood pressure monitoring
measures your blood pressure at different times and in different places (such
as at home and at work) during the day. It may be done to:
- Find out if you have
high blood pressure.
- Keep track of how
well medicine taken to reduce blood pressure is working.
- Check how
lifestyle changes, such as weight loss and exercise, are affecting blood
pressure. Home monitoring can help people feel more involved in and more in
control of their own health care.
- Watch for changes in blood
pressure that may be side effects of medicines.
- Check for problems
with high blood pressure during pregnancy or with
preeclampsia. For more information, see the topic
Preeclampsia and High Blood Pressure During Pregnancy.
Ambulatory blood pressure monitoring (ABPM) is often used
if there is a big difference between the blood pressure readings you get at
home and your readings in your doctor's office.
How To Prepare
Before you take your blood pressure:
- Don't eat,
smoke, or exercise for at least 30 minutes before
you take your blood pressure. And don't use any medicines
that can raise blood pressure, such as certain nasal sprays.
- Rest
at least 5 minutes before you take a
reading.
Sit in a comfortable, relaxed
position with both feet on the floor. Don't move or talk while you are measuring your
blood pressure.
- Try not to take your blood
pressure if you are nervous or upset.
- If you can,
use the same arm for every reading. Readings may be 10 to 20 mm Hg
different between your right arm and your left arm.
Remember that blood pressure readings
vary throughout the day. They usually are highest in the morning after you wake
up and move around. They decrease throughout the day and
are lowest in the evening.
Ambulatory blood pressure monitoring
If you have an ambulatory blood pressure monitor, you do not need to do anything to prepare. The monitor will automatically take your blood pressure while you do your normal daily activities.
How It Is Done
Specific instructions
When you buy a blood pressure monitor, be sure to buy the correct size. The size of the
blood pressure cuff and where you place the cuff on your arm can change your
blood pressure readings. If the cuff is
too small or
too large, the measurements will not be accurate. Hospital and medical supply
stores generally carry many cuff sizes and can help make sure that your cuff
fits you. See a picture of a
cuff with the proper fit.
Take your new monitor to your doctor's office to make sure it is working
right. Have your health professional take your blood pressure and then compare
that result with your own device. Ask your health professional to watch you use
your monitor to make sure that you are using it correctly. It is a good idea to
have your monitor checked every year.
Your blood pressure in your right arm may
be higher or lower than the blood pressure in your left arm. For this reason,
try to use the same arm for every reading. Blood pressure readings also rise
and fall at different times during the day. They are usually highest in the
morning and lowest in the evening. Ask your doctor if you should take your
blood pressure at the same time of day each time you take it, or if you should
take your blood pressure at different times of the day.
The
instructions for using blood pressure monitors vary depending upon the type of
blood pressure monitor you choose. Here are some general guidelines:
- Take your blood pressure while you feel
comfortable and relaxed. Sit quietly for at least 5 minutes with both feet on
the floor. Try not to move or talk while you are measuring your blood
pressure.
- Sit with your arm slightly bent and resting comfortably
on a table so that your upper arm is on the same level as your heart.
- Place the blood pressure cuff on the skin of your upper arm. You
may have to roll up your sleeve, remove your arm from the sleeve, or take your
shirt off.
Manual blood pressure monitors
Sit with your arm slightly bent and resting comfortably on a table so
that your upper arm is on the same level as your heart. Expose your upper arm
by rolling up your sleeve but not so tightly as to constrict blood flow. If you
are not able to roll up your sleeve, remove your arm from the sleeve or take
off your shirt. Wrap the blood pressure cuff snugly around your upper arm so
that the lower edge of the cuff is about
1 in. (2.5 cm) above the bend
of your elbow. A large artery (called the brachial artery) is located slightly
above the inside of your elbow. You can check its location by feeling for a
pulse in the artery with the fingers of your other hand.
If you
are using a stethoscope, place the earpieces in your ears and the bell of the
stethoscope over the artery, just below the cuff. The stethoscope should not
rub on the cuff or your clothing, since this may cause noises that can make
your pulse hard to hear. If you are using a cuff with a built-in stethoscope
bell, be sure the part of the cuff with the stethoscope is positioned just over
the artery. The accuracy of a blood pressure recording depends on the correct
positioning of the stethoscope over the artery. You may want to have another
person who can use a stethoscope properly help you take your blood pressure.
Close the valve on the rubber inflating bulb. Squeeze the bulb
rapidly with your opposite hand to inflate the cuff until the dial or column of
mercury reads about 30 mm Hg higher than your usual
systolic pressure. (If you don't know your usual
pressure, inflate the cuff to 210 mm Hg or until the pulse at your wrist
disappears.) The pressure in the cuff will stop all blood flow within the
artery temporarily.
Now open the pressure valve just slightly by
twisting or pressing the valve on the bulb. The pressure should fall slowly at
about 2 to 3 mm Hg per second. Some blood pressure devices have a valve that
automatically controls this rate. As you watch the pressure slowly fall, note
the level on the dial at which you first start to hear a pulsing or tapping sound through the stethoscope. The sound is caused by
the blood starting to move through the closed artery. This is your
systolic blood pressure. If you have trouble hearing the
start of your pulse through the stethoscope, you can check your systolic blood
pressure by noting the level on the dial when you are able to feel the pulse at
your wrist once again.
Continue letting the air out slowly. The
sounds will become muffled and will finally disappear. Note the pressure
when the sounds completely disappear. This is your
diastolic blood pressure. Finally, let out all the
remaining air to relieve the pressure on your arm.
Be sure to
write your numbers in your log book, along with the date and time.
Electronic blood pressure monitors
Sit with your arm slightly bent and resting comfortably on a table so
that your upper arm is on the same level as your heart. Expose your upper arm
by rolling up your sleeve but not so tightly as to constrict blood flow. If you
are not able to roll up your sleeve, remove your arm from the sleeve or take
off your shirt. Wrap the blood pressure cuff snugly around your upper arm so
that the lower edge of the cuff is about
1 in. (2.5 cm) above the bend
of your elbow.
For
electronic models, press the on/off button on the electronic monitor and wait
until the ready-to-measure "heart" symbol appears next to zero in the display
window. Then press the start button. The cuff will inflate automatically to
approximately 180 mm Hg (unless the monitor determines that you require a
higher value). It then begins to deflate automatically, and the numbers on the
screen will begin to drop. When the measurement is complete, the heart symbol
stops flashing and your blood pressure and pulse readings are displayed
alternately.
All blood pressure monitors
At first it is a good
idea to take your blood pressure 3 times in a row, 5 or 10 minutes apart. As
you get more comfortable taking your own blood pressure, you will only need to
measure it once or twice each time.
Check your blood pressure cuff
frequently to see that the rubber tubing, bulb, valves, and cuff are in good
condition. Even a small hole or crack in the tubing can lead to inaccurate
results.
To help develop your skills, see:
High Blood Pressure: Checking Your Blood Pressure at Home.
How It Feels
You may feel some discomfort when the
blood pressure cuff inflates, squeezing your arm.
Risks
There are no risks or complications from this
test.
Results
Blood pressure for adults age 18 and older (mm Hg)1
| Normal: |
Systolic
|
119 or below
|
|
Diastolic
|
79 or below
|
| Prehypertension: |
Systolic
|
120 to 139
|
|
Diastolic
|
80 to 89
|
| Hypertension: |
Systolic
|
140 or above
|
|
Diastolic
|
90 or above
|
Blood pressure readings of less than 90/60 mm Hg are
normal as long as you feel well. In general, the lower your blood pressure, the
better. But if you have low blood pressure and feel lightheaded, faint, or
like you may vomit, talk to your doctor.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- You have poor hearing or eyesight. An
electronic arm- or wrist-cuff model may be a better choice for
you.
- You cannot put the cuff on or twist the dial to inflate the
cuff.
- The cuff is either too large or too small for your
arm.
Blood pressure normally goes up and down from day to day
and even from minute to minute, depending upon how active you are, whether you
are standing up or sitting down, and what medicines you are taking. Other
things that can change blood pressure include being too hot or too cold,
whether you have recently eaten, and whether you are relaxed or feeling
stressed.
Home blood pressure monitoring works best when you also
record your daily activities, such as the time you take medicine if you feel
upset or stressed, in a diary. This can help explain changes in your blood
pressure readings and help your doctor adjust your medicines.
Your
blood pressure may only be high when you go to your doctor's office. This is
called
white-coat (or office) hypertension and may be caused
by stress about seeing your doctor. When you regularly check your blood
pressure at home, you may find that your blood pressure is lower when you are
not at the doctor's office.
What To Think About
- Home blood pressure monitors should be checked
regularly to make sure they are working right. You may wish to take your
monitor to your doctor's office or health department to compare blood pressure
readings. This is also a good time to have a health professional watch you take
your blood pressure to make sure that you are doing it
correctly.
- Your blood pressure may go up and down from day to day
and from moment to moment. Blood pressure tends to be higher in the morning and
lower at night. Stress, smoking, eating, exercise, cold, pain, noise,
medicines, and even talking can affect it. A single high reading does not mean
you have
high blood pressure (hypertension), and a single
normal reading does not necessarily mean you do not have high blood pressure.
The average of several repeated measurements throughout the day is more
accurate than a single reading.
- Do not adjust your blood pressure
medicines based on home blood pressure readings unless your doctor tells you
to.
- Talk to your doctor about how often you should monitor your
blood pressure. Early detection and treatment with a combination of medicine
and lifestyle changes (weight loss, diet, exercise, stress reduction) may
reduce the health risks caused by high blood pressure. If you are being treated
for high blood pressure, you may only need to check your blood pressure once a
week or less often. You may want to check your blood pressure more often if
your blood pressure is not well-controlled or if you are taking different
medicines or changing doses of a medicine.
- Most people will have
some difference in the blood pressure between the right and the left arm.
But if you have a large difference (greater than 20 mm Hg), talk to your
doctor about what this may mean.
- Some types of blood pressure
monitors can store the results of your test and transfer this information to
your computer. Some can relay these readings over a phone line to your doctor's
office.
- Blood pressure monitors that measure your blood pressure in
your finger or your wrist are not usually accurate and are not
recommended.
Other Places To Get Help
Organizations
| American Heart Association (AHA) |
| 7272 Greenville Avenue |
| Dallas, TX 75231 |
| Phone: |
1-800-AHA-USA1 (1-800-242-8721) |
| Web Address: |
www.heart.org |
| |
|
Visit the American Heart Association (AHA) website for information on
physical activity, diet, and various heart-related conditions. You can search for information on heart disease and stroke, share information with friends and family, and use tools to help you make heart-healthy goals and plans. Contact the AHA to find your
nearest local or state AHA group. The AHA provides brochures and information
about support groups and community programs, including Mended Hearts, a
nationwide organization whose members visit people with heart problems and
provide information and support.
|
|
| National Heart, Lung, and Blood Institute
(NHLBI) |
| P.O. Box 30105 |
| Bethesda, MD 20824-0105 |
| Phone: |
(301) 592-8573 |
| Fax: |
(240) 629-3246 |
| TDD: |
(240) 629-3255 |
| Email: |
nhlbiinfo@nhlbi.nih.gov |
| Web Address: |
www.nhlbi.nih.gov |
| |
|
The U.S. National Heart, Lung, and Blood Institute
(NHLBI) information center offers information and publications about preventing
and treating:
- Diseases affecting the heart and circulation, such as heart
attacks, high cholesterol, high blood pressure, peripheral artery disease, and
heart problems present at birth (congenital heart diseases).
- Diseases that affect the lungs, such as asthma, chronic
obstructive pulmonary disease (COPD), emphysema, sleep apnea, and
pneumonia.
- Diseases that affect the blood, such as anemia,
hemochromatosis, hemophilia, thalassemia, and von Willebrand disease.
|
|
References
Citations
- Joint National Committee on Prevention, Detection,
Evaluation, and Treatment of High Blood Pressure (2003). Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure JNC Express
(NIH Publication No. 03–5233). Bethesda, MD: U.S. Department of Health and
Human Services.
Other Works Consulted
- American Heart Association. (2005). Recommendations
for blood pressure measurement in humans and experimental animals. Part 1:
Blood pressure measurement in humans. AHA Scientific Statement. Hypertension, 45(1): 142–161.
- Joint National Committee on Prevention, Detection,
Evaluation, and Treatment of High Blood Pressure (2003). Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure JNC Express
(NIH Publication No. 03–5233). Bethesda, MD: U.S. Department of Health and
Human Services.
- Pickering TG, et al. (2008). Call to action on use and reimbursement for home blood pressure monitoring. A joint scientific statement from the American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association. Hypertension, 52(1): 10–29.
Credits
| By |
Healthwise Staff |
| Primary Medical Reviewer |
E. Gregory Thompson, MD - Internal Medicine |
| Specialist Medical Reviewer |
Robert A. Kloner, MD, PhD - Cardiology |
| Last Revised |
April 5, 2011 |
