Blood Pressure Monitoring: How to Get It Right
Five ways to get accurate blood pressure numbers and steer your health in the right direction
Most people will have high blood pressure at some point in their lives. In fact, it's estimated that by age 55, those who don't already have high blood pressure face a 90% chance of developing the condition. But you can help keep your RealAge younger by monitoring your blood pressure, learning how to read your blood pressure numbers and getting the treatment you need if they’re consistently high.
Why Blood Pressure Monitoring is Important
High blood pressure is a significant risk factor for heart attack, stroke, kidney disease, and vision loss. It often is referred to as the silent killer because it rarely causes any symptoms until considerable organ damage has occurred. That's why getting regular, accurate blood pressure readings are vital to your long-term health.
But what if the measurements you rely on are imprecise? Could inaccurate readings be putting your health at risk? It's possible.
Imprecise measurements, even those that are off by just a few points, can lead to inappropriate treatment. If your numbers are falsely low, you may not receive vital medication that, in the long run, could save your life. Conversely, if your blood pressure numbers are falsely high, you may be given medication you don't really need.
Why Readings May Be Off
You might be surprised at how easy it is to influence the accuracy of such a seemingly simple tool as the blood pressure monitor. Several factors, such as talking (answering a nurse's question) or having a full bladder (because you thought you might be asked to give a urine sample), can temporarily change your blood pressure enough to result in false high or low blood pressure numbers.
And operator error -- even at the doctor's office -- is one of the leading causes of inaccurate measurements. Studies of healthcare professionals consistently show that doctors and nurses rarely follow recommended guidelines for accurate blood pressure monitoring. And measurements taken casually, without following standard procedures, produce unreliable results.
How did your last test go?
So how precise was your most recent blood pressure reading? Think back to the last time you had your blood pressure measured, whether it was at the doctor's office, on a machine in the pharmacy, or at home, using a self-monitoring device.
1. Were you sitting quietly for 3-5 minutes prior to your blood pressure being taken?
Blood pressure can be affected by movement and anxiety, so one of the recommended guidelines for getting an accurate measurement is that you sit and relax for 3-5 minutes before a blood pressure reading is taken. But in a busy healthcare setting, this doesn't always happen. In one study, only 4% of healthcare professionals followed this procedure.
If you're self-monitoring, it's easy to rush the process as well. Slow down and take the time to get it right.
2. Was the cuff size appropriate for your arm?
An appropriate-sized cuff -- the part of the monitor that wraps around your arm -- is essential for an accurate blood pressure reading. Using a cuff that is too small for your arm will overestimate your blood pressure, and one that is too big will underestimate it. Still, many clinicians use one standard-sized cuff for all patients.
If you're monitoring your numbers with a home device, make sure the cuff you have is the right size for your arm. Read on to learn more.
3. Was your blood pressure measured in both arms?
In some people, there is a significant difference in blood pressure numbers between their right and left arm. Although the reason for this is unclear, guidelines recommend that blood pressure be measured in both arms at the initial consultation. If there is a significant difference between the two readings, the arm with the higher reading should be used for future monitoring.
4. Were two measurements taken a few minutes apart?
A single measurement does not provide an accurate assessment of your blood pressure. For more reliable results, at least two readings should be taken a few minutes apart, and the average of the readings should be recorded.
5. During the reading, was your arm supported and resting at heart level, with both feet flat on the floor?
Both body and arm position can influence blood pressure during monitoring, so it's important to follow the guidelines. For the most accurate results, you should be sitting comfortably in a chair with a backrest (not on the examination table) with your feet flat on the floor, legs uncrossed. Your arm should be supported and resting at heart level.
Read on to learn more about how you can make mismeasurements a thing of the past and help keep high blood pressure at bay.
Blood Pressure Basics
Blood pressure measures the force exerted against the walls of your arteries as your heart pumps blood throughout your body. The pressure is affected by both the strength with which the blood is pushed through your arteries and the health of your arteries -- their size and flexibility. As arteries become less supple with age or as a result of lifestyle factors, the pressure inside the arteries increases. And if the pressure remains high, it can damage your heart by making it work too hard. Over time, high blood pressure also may cause damage to your arteries, brain, kidneys, and eyes.
But there are many things you can do to prevent, delay, or reduce high blood pressure, starting with knowing your numbers.
Blood pressure readings are made up of two numbers, for example, 120 over 80 (written as 120/80 mm Hg). The top number represents systolic pressure, the force against the artery walls when the heart pumps. The bottom number represents diastolic pressure, the force on the artery walls when the heart is at rest between beats.
Both numbers are important, but only one of them needs to be high for you to have hypertension.
Blood Pressure Numbers You Should Know
A few years ago changes were made to the classifications of blood pressure, and a new category -- prehypertension -- was introduced.
Check out the table, below, for the most up-to-date classifications from the National Heart, Lung, and Blood Institute.
|Blood pressure category||Systolic |
|Stage 1 Hypertension||140–159||or||90–99|
|Stage 2 Hypertension||≥160||or||≥100|
* The RealAge Optimum is 115/76 mm Hg.
So Why the New Category?
The new category of prehypertension was created as an early warning system to identify people who may be at risk for developing high blood pressure. Initially the new category, which includes blood pressure numbers that were previously considered normal, led to controversy and confusion. But results from recent studies provide support for the move, making it all the more important to get accurate readings. The difference between normal and prehypertension is slight, but can have significant health consequences.
Research shows that people with blood pressure classified as prehypertensive have a significantly increased risk of developing hypertension and cardiovascular disease compared to those with normal blood pressure.
Put simply, if you have prehypertension, it means you don't have high blood pressure now but are likely to develop it in the future. The good news is that by making a few healthy changes in your life, you may be able to keep your blood pressure from creeping up any further.
If you have stage 1 or stage 2 hypertension, you may be able to bring your numbers down with a healthy lifestyle approach, including:
- Eating a diet rich in fruits, vegetables, and whole grains
- Being more physically active
- Limiting the amount of alcohol your drink to no more than 1 drink per day for women, 2 drinks per day for men
- Maintaining a healthy weight
If that doesn't reduce your blood pressure enough, you also may need to consider medication. Talk to your doctor about regular blood pressure monitoring, setting goals and creating a plan of action.
What is Pulse Pressure?
Pulse pressure (pp) is the difference between systolic and diastolic blood pressure. For example, if your blood pressure is 138/80, your pulse pressure would be 58 (138 - 80 = 58).
High pulse pressure, which is thought to be an indicator of stiffening arteries, is an independent risk factor for cardiovascular disease in older adults. So what's high? In a recent study, men with a pulse pressure of 57 or more had a significantly increased risk of cardiovascular mortality compared to those with a pulse pressure of 38 or less.
Measure for Measure
No matter what your blood pressure is, it's important to get accurate measurements in order to help guide your healthcare and lifestyle decisions.
So the next time you have your blood pressure numbers checked -- whether it's done by your doctor or you do it yourself at home -- follow these six steps for reliable readings:
- Use the correct cuff size and wear short sleeves. A cuff that is too small or too big can lead to inaccurate readings. If you're buying a home monitor, ask your doctor to measure your arm so you know what cuff size to look for. Also, the cuff needs to fit snuggly around your bare upper arm, so short sleeves are your best bet. Rolled up long sleeves may constrict your arm, which could alter your blood pressure reading.
- Avoid caffeine, cigarettes, and alcohol for at least 30 minutes before you measure. They can cause a temporary increase in blood pressure.
- Use the restroom. A full bladder can affect the accuracy of your reading.
- Sit and rest quietly for a few minutes It's best to sit someplace quiet, where you feel relaxed. This may not be possible when you're at the doctor's office, but if you're at home, it's worth taking the time to get it right. And during your reading, try not to talk or move about.
- Be FABulous. To get an accurate blood pressure measurement, it's important that your body is in the right position. Think FAB (Feet, Arm, and Back) to help you remember your pose. You should have your Feet flat on the floor, your Arm supported and resting at heart level, and your Back supported against a backrest or wall.
- One arm, two readings. Blood pressure can differ between arms, so always use the same arm to get your measurements. And because blood pressure changes easily and often, it's best to take two or three readings a few minutes apart, and then work out the average.
Blood pressure fluctuates a lot over a 24-hour period and tends to be high in the morning and low in the evening. So if you're taking your blood pressure at home, try to take your measurements at about the same time each day. That way, when you review your readings, you'll be comparing "like with like."
Why Monitor at Home?
At-home blood pressure monitoring is a good way to be actively involved in keeping your blood pressure under control. It also may provide a more accurate picture of your blood pressure than occasional measurements taken at the doctor's office. Studies show that home measurements, when taken correctly, are better predictors of cardiovascular risk than office measurements.
In addition, some people's blood pressure readings are considerably higher when measured by a doctor or nurse in a medical setting than when measured elsewhere. This is known as the white-coat effect. It's estimated that 20% of people diagnosed with hypertension based on clinical measurements alone actually have entirely normal blood pressure. Home monitoring can be a useful tool in determining whether a person's high blood pressure reading is accurate or is simply a result of the white-coat effect.
Self-monitoring also may be used to help assess how well medications or lifestyle modifications are working. And there is evidence to suggest that home monitoring may help people reduce their blood pressure.
Choose the Right Blood Pressure Monitoring Device
There are so many devices on the market for measuring blood pressure at home that it can be difficult to know which one to choose. Most people who measure their blood pressure at home use an automatic machine with a digital display. These are easy to use. The cuff inflates and deflates automatically, the numbers are clear and easy to read, and many machines can store and print multiple blood pressure readings. But they do have their downsides. Some are made for use on the left arm only, and they can be expensive.
Here are a few simple guidelines to help you choose the right blood pressure monitoring device:
- Choose a device that measures blood pressure from your upper arm. Wrist and finger monitors are not accurate.
- Choose a monitor with a display that's easy for you to read.
- A monitor that can save, download, and print your readings is best for accurate record-keeping.
- Before you buy, verify that the monitor you're considering has been independently tested, validated, and approved for home use. For a regularly updated list of validated home blood pressure monitors, visit the Web site of the dabl® Educational Trust.
Once you've bought a measuring device, make an appointment with your doctor and take the device with you. That way, if you have any questions about home monitoring or how to read blood pressure numbers, your doctor can provide guidance. Also, some monitors need to be calibrated or checked for accuracy on a regular basis. Your doctor should be able to do this for you.
For more detailed information on choosing and using a home blood pressure monitor, check out information from the American Academy of Family Physicians.
Keeping an eye on your blood pressure is an easy and effective way to monitor your health and prevent high blood pressure from sneaking up on you.