How does a blood pressure test work?
A blood pressure test measures how hard your
is pushing against the walls of your arteries at two key moments — when your heart is pumping out blood and when it’s at rest. That’s why there are two numbers that make up your blood pressure reading:
Systolic blood pressure: This is the top/first number. It’s the pressure in your arteries when your heart is beating and sending blood into your arteries.
Diastolic blood pressure: This is the bottom/second number. It’s the pressure in your arteries when your heart is at rest between beats.
There are two main ways your healthcare provider can measure your blood pressure:
Manually: Your provider uses a fabric cuff and a gauge that shows your blood pressure numbers. They wrap the cuff around your upper arm and inflate it so it squeezes your arm. They use a
to listen to blood flow in your arm while the cuff deflates.
Automatically: Your provider uses an electronic device that inflates and deflates the cuff. The device has a digital read-out screen that shows your blood pressure numbers. Your provider doesn’t use a stethoscope with this method.
How do I prepare for a blood pressure test?
To get the most accurate blood pressure reading:
Don’t
, exercise or have
for 30 minutes before your appointment
Go to the bathroom right beforehand so your bladder is empty
Sit for at least five minutes without talking before your provider begins the test
You may also want to wear short sleeves. This will make it easier for your provider to put the cuff on your arm.
What can I expect during the test?
A blood pressure check is fast and noninvasive. Nothing goes into your body. Your provider wraps a cuff around your upper arm. The cuff squeezes and then releases over the course of about a minute. During this time, your provider records your blood pressure numbers.
The cuff gets very tight around your arm when it’s inflated. This might feel uncomfortable, but it’s only for a few seconds.
Your provider will help you sit in a position that allows the best reading. For example, you should:
Sit up straight with your feet flat on the floor (don’t cross your legs)
Rest your arm on a flat surface in front of you so it’s at heart level
Your provider may check your blood pressure more than once during your appointment. This can help them get the most accurate reading, especially if you’re nervous.
Your provider will check your blood pressure manually or automatically — or both.
Manual blood pressure measurementYour provider will follow these steps to manually measure your blood pressure:
Wrap the cuff around your upper arm: This will go just above your elbow. It’s connected to a gauge that looks a bit like a clock or old-fashioned speedometer. It has numbers around the edges and a needle in the middle.
Inflate the cuff: Your provider will squeeze a ball connected to the cuff. The cuff will feel tight around your arm. This squeezing action briefly stops blood flow in your
. The gauge will increase in pressure.
Deflate the cuff: Your provider will slowly remove air from the cuff. This makes the gauge needle start to come down.
Wait for the sound of blood flow: As the cuff deflates, blood can start flowing through your brachial artery again. When this happens, your provider will hear tapping sounds through the stethoscope. The number on the gauge at this moment is your systolic pressure.
Wait for the sounds to stop: Your provider will keep listening to blood flow in your arm while watching the gauge. When the sounds stop, this means the pressure in the artery is higher than the pressure in the cuff. So, the cuff is no longer blocking the blood flow. The number on the gauge now is your diastolic pressure.
Automatic blood pressure measurementAnother option is to measure your blood pressure using an automatic device. It’s similar to what you might
. But providers test these devices often to make sure they’re accurate.
Your experience won’t be much different from a manual reading. A cuff will still squeeze your arm. But your provider won’t use a stethoscope or look at a gauge. Instead, they’ll check the device’s digital read-out screen to see your blood pressure numbers.