The other day I went for a bicycle ride on the local trail and I wondered how cool it would be to take my blood pressure right now. A wrist blood pressure monitor quickly popped into my mind as the perfect way to do it. You may have thought about using one and their accuracy. Are wrist blood pressure monitors accurate?
Wrist blood pressure monitors are not as accurate as upper arm monitors. Numerous studies indicate a difference between the readings of wrist blood pressure monitors and traditional arm cuff devices. In addition, the American Heart Association does not recommend them.
In addition to the discrepancies of the wrist blood pressure monitors there are mistakes, particularly one critical mistake, people are making. This post will dive into all the details you need to know about wrist blood pressure monitors and the #1 mistake people are making that can affect their health.
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Studies Indicate That Wrist Blood Pressure Monitors Are Not Accurate
The following 3 studies show how inaccurate wrist blood pressure monitors can be. These results are concerning considering people are making decisions based on their results with wrist blood pressure monitors.
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A 2010 study published in the Journal Of Clinical Hypertension found significant differences between the arm and wrist when blood pressure measurements were taken on 261 people.
Many patients had a difference of systolic and diastolic blood pressure readings of 5 or 10 mm Hg or more between the wrist and upper arm. What’s a little scary is approximately one-third had a difference of equal or greater than 10 mm Hg 1.
A study in 2013, in Blood Pressure Monitor, used wrist and arm monitors to automatically measure blood pressure over a 24-hour period. Both the systolic and diastolic blood pressure measurements from the wrist monitor were significantly different at times compared with the arm monitor 2.
Another study was published in 2016 in the Journal Hypertension. Researchers trained 721 people to use a wrist blood pressure monitor and a traditional arm cuff monitor.
When the participants used the wrist devices at home, 86% of them had blood pressure measurements that were at least 5 mm Hg higher at the wrist compared to the arm. Almost 75% of those participants had readings at least 10 mm Hg higher compared to the arm.
The researchers surmised some of these discrepancies were due to the participants inaccurate positioning of their wrists 3.
Wrist blood pressure accuracy is only one of many monitor topics covered in my article, Home Blood Pressure Monitors – Things To Know. Check out the others which you may find interesting.
The Difference In Blood Vessels That Make A Wrist Blood Pressure Monitor Not Accurate
In addition to the difference in measurements between the wrist blood pressure monitor and the arm, most people are finding the difference at the wrist is often higher.
This is so because the arteries in the wrist are narrower and closer to the surface of the skin compared to those in the upper arm. The difference in the arteries and their location make the wrist blood pressure monitor less accurate.
This is the main reason why the American Heart Association recommends against their use and the finger monitor for the same reason 4.
The #1 Mistake That Makes A Wrist Blood Pressure Monitor More Inaccurate
Regardless what kind of blood pressure monitor you’re using, there are certain guidelines which must be followed to achieve an accurate reading. The #1 mistake people are doing goes for all monitors but is committed more when people are using a wrist monitor.
This mistake is in regards to the height of the blood pressure cuff at the time of measurement.
To get an accurate blood pressure reading with a wrist monitor the cuff must be at the same level as the heart. Blood pressure measured below or above the heart will reflect hydrostatic pressure. Hydrostatic pressure in blood vessels is caused by the weight of the blood above it in the vessels.
It will be lower above the heart where blood has been pushed up against gravity. It will be higher below the heart where the weight of the blood above the measurement point will add to the pressure contributed by the heart.
This explains why, whenever possible, blood pressure should be measured with an arm cuff. This is so because when the person is either sitting or standing it usually puts the cuff at heart level. But if you find it necessary to use a wrist monitor, make sure your wrist cuff is at the same height as your heart.
The easiest way to do this is to start with your upper arm at the side, close to your torso. Bend at the elbow raising your forearm up and across your chest with your wrist at the level of your heart.
When using a wrist blood pressure monitor many people make the mistake of positioning their arm the wrong way. Usually, they position their arm the same exact way they would if they were using an arm cuff monitor.
I can understand why someone would do this, it’s a comfortable position and the most natural way of doing it. But doing this will usually give you a higher reading making the wrist blood pressure monitor measurement inaccurate and not at the fault of the monitor.
How To Check The Accuracy Of A Wrist Blood Pressure Monitor
If you have a wrist blood pressure monitor, take it with you on your next doctor appointment. Your doctor or nurse can check your blood pressure with both a standard upper arm monitor and your wrist monitor.
Both results can be compared to check if your wrist blood pressure monitor is accurate. Bring your device in about once a year to make sure it remains accurate 5.
In addition, make sure the wrist blood pressure monitor you have is a validated device. All self-measured blood pressure devices sold in the United States are required to meet standards.
However, even a validated device will not provide accurate readings in all patients. This is just another reason to have your device checked with your doctor once a year.
The new 2017 blood pressure guidelines recommends that all blood pressure monitors have peer-reviewed publications showing they have been tested for the validation of clinical accuracy.
The American Medical Association is working with the American Heart Association to create a validated device listing. When that listing becomes published I will add a link to it.
A Reason To Use A Wrist Blood Pressure Monitor
After giving you reasons why a wrist blood pressure monitor is inaccurate, sometimes a person might have to use one in the following situations:
- Some people can’t take blood pressure at the upper arm because they have a very large arm due to being overweight. When this is the case, the arm cuff cannot properly be wrapped around their arm.
- There are times when a person’s arm is cone shaped which also makes it difficult to fit the cuff around the arm properly.
- Some people may have arm or hand mobility limitations where an upper arm cuff cannot be used.
If you require a wrist blood pressure monitor, check out another one of my blog posts for the monitor I recommend right here Omron Gold Wrist Monitor.
If an arm cuff is not properly wrapped around the upper arm, it can result in inaccurate blood pressure readings 6. An arm cuff wrapped around a cone shaped arm can result in blood pressure discrepancies that may be as large as 10 mm Hg.
For arm cuffs too small around a large arm, studies have shown a person’s systolic blood pressure measurement can increase 10 to 40 mm Hg! In these cases, using a wrist blood pressure monitor while following the proper procedure is acceptable.
How to take blood pressure with a wrist cuff? The best way to take your blood pressure with a wrist cuff:
- Don’t smoke, eat, drink or exercise 30 minutes prior.
- Sit with your back straight and supported, feet flat on the floor.
- Your arm should be on a flat surface with your wrist at heart level.
- Measure at the same time everyday.
- Don’t measure over clothes.
Which blood pressure monitor is best wrist or arm? An arm blood pressure monitor is better than a wrist monitor. The blood vessels in the wrist are narrower and closer to the surface of the skin compared to the more accurate upper arm blood vessels. It’s easier to keep the upper arm at heart level which is required for an accurate reading.
Read Next – More BP Monitor Articles!
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- Wiley: Does ‘‘Hidden Undercufﬁng’’ Occur Among Obese Patients? Effect of Arm Sizes and Other Predictors of the Difference Between Wrist and Upper Arm Blood Pressures
- National Center for Biotechnology Information: Comparison of wrist-type and arm-type 24-h blood pressure monitoring devices for ambulatory use
- Hypertension: Poor Reliability of Wrist Blood Pressure Self-Measurement at Home
- BCcampus: Nerves, Blood Vessels and Lymph
- American Heart Association: Monitoring Your Blood Pressure At Home
- Harvard Health: Avoid these common blood pressure measuring mistakes