6 Things Doctors Want You to Know About Home Blood Pressure Monitors

More than 100 hundred million Americans have hypertension, yet only about half of them have it controlled, according to a 2018 review published in the medical journal Circulation. That’s a problem because high blood pressure puts a strain on your heart and arteries, dramatically raising your risk of heart disease. If you have high blood pressure—or even if you’ve had one or two borderline readings in your physician’s office—your doctor may suggest checking it at home via a home blood pressure monitor. “It can be a good way to help determine if you actually do have high blood pressure, or if you have white coat hypertension, which is when your blood pressure is high in your doctor’s office but normal in everyday settings, like at work or home,” explains Luke Laffin, MD, a preventive cardiologist at the Cleveland Clinic in Ohio. And if you do have hypertension, regular home monitoring seems to help about 70 percent of people get it under control, according to research presented at the 2018 American Heart Association scientific sessions. Here’s what doctors want you to know:

Invest in the correct type

You don’t need to spend $200 on a blood pressure monitor with bells and whistles like wireless capability, says Dr. Laffin. You can find an excellent one in the $40 to $60 range. The most important thing is to make sure it’s the right kind. Home blood pressure monitors come in arm cuff, wrist cuff, and finger models. Of all three, an automatic arm cuff model is the most accurate, advises Dr. Laffin. He also recommends avoiding the blood pressure measurement apps for your phone. “They don’t work, and they haven’t gone through good testing,” he says. (Check out some more health gadgets that can help save your life.)

Size matters

When it comes to picking the right blood pressure monitor, the size of the cuff is the most important. “If the cuff doesn’t fit properly on your arm, it may give you inaccurate readings,” explains Dr. Laffin. You want to make sure that the blood pressure monitor has a cuff that fits the circumference of your upper arm or wrist (use a tape measure to check yours). The 2017 AHA/ACC High Blood Pressure Clinical Practice Guidelines, which both the American College of Cardiology and the American Heart Association endorse, recommends these sizes:

Adult small: Arm circumference of 22 to 26 centimeters (about 8.5 to 10 inches).

Adult average: Arm circumference of 27 to 34 centimeters (about 10.5 to 13 inches).

Adult large: Arm circumference of 35 to 44 centimeters (about 13.5 to 17 inches).

Check it with the pros, first

About a third of home blood pressure monitors are off by at least five points, according to a 2016 study published in the journal PLOS One. When shopping for a home blood pressure monitor, the American Medical Association recommends making sure it’s been certified by one of three organizations: the Association for the Advancement of Medical Instrumentation, the British Hypertension Society, or the European Society of Hypertension. Then, before using it, have your doctor’s office check it against their model. “If their systolic (upper number) reading is within about 10 mm, it’s accurate enough to use,” says Dr. Laffin. It’s also a good idea to have a doctor or nurse observe you taking your own blood pressure reading, to make sure you’re doing it correctly.

Prep a little, beforehand

Don’t smoke, consume caffeine, or exercise within 30 minutes of measuring your blood pressure to ensure the most accurate reading. Got to pee? Go to the bathroom before you check your blood pressure: A full bladder can tack on 10-15 mm Hg, according to the American Heart Association. Don’t multi-task, either: chatting away in a conversation with someone can also increase blood pressure by 10-15 points. Finally, roll your sleeves up. Yes, it’s a pain, but putting the cuff over your clothing, rather than your bare arm, can inflate your blood pressure by up to a whopping 40 mm Hg. ” Here are some more surprising things that can affect your blood pressure readings.

Sit the right way

Choose a hard-backed chair and sit with your back straight and supported; leaving your back unsupported can increase your measurements by 5-10 mm Hg, according to the American Heart Association. Your feet should also be flat on the floor and your legs shouldn’t be crossed—dangling or crossed legs can add anywhere from 2 to 10 points to a reading. Your arm should be supported on a flat surface with your upper arm at heart level, the bottom of the cuff placed directly above the bend of your elbow. Not doing that can also raise your blood pressure by about ten points.

Take at least two

Each time you measure your blood pressure, take two or three readings one minute apart and record the results, recommend experts at the American Heart Association. This helps ensure that your readings are accurate. (If your monitor has built-in memory to store your readings, you can just take it with you to show your doctor at your next appointment.) Some monitors also allow you to upload your readings to their website after you register your profile. It’s also important to take the readings at the same time each day, such as morning and evening. “I tell my patients to take it first thing in the morning, after they’ve gone to the bathroom and brushed their teeth, but before they’ve eaten anything or taken their medications,” says Dr. Laffin. Check out some easy ways to treat your high blood pressure at home.