Learning how to take blood pressure is a skill that takes
practice to perform properly. Once learned, it can be a helpful tool in
managing your and your family's health care.
What do you need to
take blood pressure?
You need three things to take blood pressure: a blood
pressure cuff, sphygmomanometer, and stethoscope. The cuff gets wrapped around
the limb. It should have a tube attached to it with a bulb and valve at the end
to inflate and deflate the cuff. A sphygmomanometer is connected by tube to the
cuff and tells you how much air pressure is in the cuff. The stethoscope allows
you to listen to and assess the blood pressure.
For an accurate blood
pressure reading, the blood pressure cuff should be long enough to cover
two thirds of the limb being used. A cuff that is too large or too small can
give an erroneous blood pressure reading. This is also true if the cuff is
either too loose or too tight around the limb. You should be able to insert 1
finger between the cuff and the limb for an accurate fit.
To avoid injury,
never use a limb that has an intravenous infusion or a dialysis fistula in it.
Also never use the arm or leg on the same side where surgical removal of
axillary or hip lymph nodes has occurred. This may be the case with some cancer
Wait 30 minutes
after exercise, smoking or digesting caffeine before taking blood pressure.
Whatever arm is being used to take blood pressure, keep it at the level of the
heart. If it is above the heart, blood pressure will increase. If it is below
the heart, blood pressure will decrease.
Ask the person to sit down with his or her arm
slightly bent and resting on a table. The patient’s feet should be on the floor
and they should be resting quietly for at least 5 minutes.
Wrap the cuff around the upper arm about one
inch above the elbow. Follow the guidelines above for proper cuff fit.
Locate the brachial pulse which is on the inside
of the elbow. Place the diaphragm of the stethoscope (the flat part) over the
Using the bulb attached to the cuff, inflate the
cuff to about 30mmHg above where the person's normal systolic blood pressure
is. The systolic is the top number of a blood pressure reading. So if the
normal systolic blood pressure for this person is 120mmHg, inflate the cuff to
Slowly open the valve on the bulb to release the
pressure in the cuff. The pressure should decrease at the rate of no more than
2-3mmHg per second.
Using the stethoscope, record when you hear the
first pulse or thump sound. As the pressure decreases, you will continue to
hear the pulse sounds until they disappear. Record when you hear the last pulse
The first sound heard is the systolic pressure,
which is the maximum pressure exerted when the heart contracts. This is the top
number. The last sound heard is the diastolic pressure, which is the minimum
pressure in the arteries while the heart rests. This is the bottom number. So
if you heard the first sound at 135mmHg and the last sound at 90mmHg, you would
record the blood pressure as 135/90. Click here to find out how to interpret