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Wellness

The 2 most important things to look for in a blood pressure monitor

Not every blood pressure monitor is a good one. Here’s how to find the right one for you.

home blood pressure monitor

The American Heart Association recommends that people with hypertension measure their blood pressure at home.

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The Apple Watch's electrocardiogram app is clear indicator that medical devices are moving out of the doctor's office and into our homes. And for the most part, that's a good thing -- health and fitness products let people keep tabs on various vital signs without having to pay for an office visit. One wellness area that's particularly hot is blood pressure. Organizations like the American Heart Association recommend that people with high blood pressure measure it at home and the heart health industry has stepped up to help make that happen. 

Read: The best blood pressure monitors for at-home use  

From a blood pressure cuff that doubles as a smartwatch to smartphone apps that measure your systolic and diastolic blood pressure using just the tip of your finger, monitors are becoming more compact and easier to use. But, the AHA warns, that doesn't mean they're accurate. But before you buy just any old home blood pressure monitor, here are two big things cardiologists want you to know. 

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1. An upper-arm cuff should be your first choice 

When it comes to at-home monitoring, new guidelines from the AHA only recommend the use of upper-arm cuff oscillometric devices that have successfully passed validation protocols. (Oscillometric devices automatically detect and analyze pulse waves so you don't have to rely on someone to listen with a stethoscope.) Although other options -- like wrist and finger cuffs and wearable sensors -- exist, upper arm cuffs are the most accurate, says Yale Medicine cardiologist Erica S. Spatz, MD.

The AHA recognizes validation protocols from the following organizations: the German Hypertension League, the Association for the Advancement of Medical Instrumentation, the European Society of Hypertension and the British Hypertension Society -- with the BHS protocol's being the most complex and thorough. A new international universal validation protocol is being developed that may become the new standard, so keep an eye out for that.

Qardio Arm blood pressure monitor

The Qardio Arm wireless blood pressure monitor has passed British and Irish Hypertension Society validation protocols. 

Qardio

Many blood pressure monitors currently being sold haven't been validated. So before you buy one, check to make sure it has. You can find a list of validated monitors -- like these from Qardio and Omron -- on the British and Irish Hypertension Society and Dabl Educational Trust websites.

Another important factor is if the person who will be using the blood pressure monitor is a child, pregnant or has atrial fibrillation or a large arm circumference, the monitor you buy should also have been validated within these populations. 

2. Find a cuff that fits

These days home blood pressure monitors come with a lot of bells and whistles, like smartphone apps and Bluetooth connectivity, but the most important feature to look for is a cuff that fits your arm, properly compressing the brachial artery.

"All too often, the fit of the blood pressure cuff is imperfect," Spatz says. "This can result in under- or overestimation of the blood pressure -- and many people may be misdiagnosed [with hypertension]."

But here's the good news: "Guidelines exist for how large a cuff one needs based on the length and circumference of your arm," says cardiologist Jennifer Haythe, MD, co-director of Columbia Women's Heart Center. "When you visit your doctor ask them what size cuff is appropriate for you."

You can also take the measurements yourself or with the help of a pharmacist. 

"The first step is to measure the circumference of the upper arm; use the middle of the upper arm around the bicep," Spatz says. "Take the circumference, in centimeters, and multiply it by 80% to get the right length and 40% to the get the right width of the bladder cuff. The bladder of the cuff is the part that fills with air, not the extra length of Velcro." 

And then use these AHA guidelines:

blood-pressure-arm-cuff-sizes
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"Upper arm cuffs come in an extra-large size, which should fit most large arms," Haythe says. "If it's too small, your doctor may recommend a thigh cuff to be used on the upper arm." According to the AHA, there is data showing this method can be accurate, but research is limited. 

If you have larger arms that are significantly wider near your shoulder than your elbow, you may also want to get a cone-shaped or "contour" cuff. Research finds that using standard cylindrical cuffs can produce inaccurate measurements because the variation in arm size causes the bladder to expand irregularly.

If an extra-large cuff does not fit, the AHA recommends measuring your blood pressure at the wrist. Although measuring at the wrist tends to be less accurate than the upper arm, a meta-analysis shows it tends to be better than the forearm or finger. 

contour-cuff

An example of a contour-style blood pressure cuff. 

Medline

"Arms come in all shapes and sizes, and people with obesity should not feel bad about having a difficult time finding the right cuff size," Spatz says. "It is really unfortunate that the cuffs have not evolved to match different arm sizes."

If you do end up needing a wrist-based blood pressure monitor, again, check that it's been validated. And then follow these instructions, with one change: "Rest your elbow on a table and bring the cuff to the level of your heart, as when reciting the pledge of allegiance," says Spatz. Keep your arm relaxed and your hand resting against your chest until the reading is complete. 


The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives. 

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