Blood Pressure

What is blood pressure?

Blood pressure is a measure of the force of blood inside your arteries. Each time your heart beats, it pumps blood into a large artery called your aorta. This happens 60 to 100 times a minute, 24 hours a day. Your aorta connects to other arteries that deliver oxygen and nutrients to all your organs and tissues.

Your blood pressure doesn’t stay the same all the time. It changes based on what you’re doing. When you’re exercising or excited, your blood pressure goes up. When you’re resting, your blood pressure is lower. Your blood pressure can also change because of medicines you take, shifts in your body position and aging.

Why is blood pressure important?

Blood pressure matters because it can have a big effect on your health. For example:

• High blood pressure (hypertension) is a major risk factor for cardiovascular disease. Severely high blood pressure, known as a hypertensive emergency, can be life-threatening.
• Low blood pressure (hypotension) can cause dizziness, fainting and fall-related injuries. Severely low blood pressure limits blood flow to major organs and can lead to life-threatening complications like shock.

You usually can’t tell what your blood pressure is just by how you feel. The only way to know your blood pressure is to measure it with proper equipment. This typically happens at your healthcare provider’s office. You can also check your blood pressure at home — but this shouldn’t replace seeing your provider.

When should I have my blood pressure checked?

You should check your blood pressure at least once a year. Your healthcare provider will measure it for you at each annual physical exam. You may need more frequent blood pressure checks if your provider is concerned about your numbers or wants to see how well treatment is working.

Your provider may also ask you to check your blood pressure at home. They’ll tell you how often to do this — anywhere from several times a day to once a week.

In certain situations, they may ask you to do 24-hour blood pressure monitoring. This lets your provider see how your blood pressure changes over the course of your day and even while you sleep. It can also diagnose white coat syndrome. This is when your blood pressure is high at your provider’s office because you’re nervous.

How does a blood pressure test work?

A blood pressure test measures how hard your blood 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 stethoscope 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 smoke, exercise or have caffeine 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 measurement

Your provider will follow these steps to manually measure your blood pressure:

1. 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.
2. 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 brachial artery. The gauge will increase in pressure.
3. Deflate the cuff: Your provider will slowly remove air from the cuff. This makes the gauge needle start to come down.
4. 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.
5. 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 measurement

Another option is to measure your blood pressure using an automatic device. It’s similar to what you might use at home. 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.

What should I expect after the test?

Once your provider measures your blood pressure, they’ll continue with the rest of the physical exam. They may talk with you about your blood pressure numbers.

You’ll know your blood pressure reading right away. But if your numbers are high, you may need to come back for another appointment. This is because your provider needs two or more readings, on different days, to diagnose high blood pressure (hypertension). They take an average of these readings.

If you’re diagnosed with hypertension, your provider will talk with you about treatment options. Medicine can lower your blood pressure and help protect you from serious complications down the road. If you’re diagnosed with low blood pressure, your provider will find the underlying cause and treat it.

What are the blood pressure ranges?

Healthcare providers generally use the following categories to describe your blood pressure (these apply to all adults, regardless of sex):

If your top number and bottom number fall into two different categories, your provider will use the higher category. For example, if your blood pressure is 132/78, your reading would fall into the stage 1 hypertension category.

An ideal blood pressure for most adults is lower than 120/80 mm Hg (millimeters of mercury). This means your systolic (top) number is below 120 and your diastolic (bottom) number is below 80. But blood pressure that’s too low may be a cause for concern. Hypotension is blood pressure below 90/60 mm Hg.

Keep in mind that what’s ideal or even normal can vary from person to person. For example, certain medical conditions or medicines could affect what your personal blood pressure goal should be. Be sure to ask your provider what that number is and how you can reach it.

When should I call my doctor?

Contact your healthcare provider if:

• Your blood pressure reading at home is elevated or low
• You have symptoms of hypotension (like dizziness, fainting or nausea)
• You have any questions about your blood pressure or treatment plan

Call 911 or your local emergency services number if:

• You think you’re having a hypertensive crisis: This means your top number is 180 or higher and/or your bottom number is 120 or higher. You may also have other symptoms like shortness of breath, headache, chest pain or blurry vision.
• You have hypotension and develop complications: Seek medical care right away if you faint or fall and hit your head. You should also seek care if you have symptoms of shock, like feeling cold, being sweaty or breathing quickly.