How It Is Done
Specific instructions
When you first get a blood
pressure monitor, take it 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.
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. The inflatable part of the
cuff needs to wrap around at least 80% of your arm. 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
.
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
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.