Is Your Home Blood Pressure Monitor Reliable?
Betty Chaffee, PharmD, is owner and sole proprietor of BetterMyMeds, a Medication Management service devoted to helping people get the maximum benefit from their medications.
Nearly half of adults in the United States have high blood pressure. Many monitor their blood pressure at home. If you use a home blood pressure (HBP) monitor, you're already doing a great job taking care of your health. But are you sure your monitor is giving you reliable results? It's important to care for your monitor, too. They don't last forever. Inaccurate results can cause you to worry needlessly, or keep you feeling content when you should be concerned. I was recently reminded of this by a patient (thank you!). So let's talk about how to make sure you're getting reliable results from your HBP monitor.
Before we go there, though, a quick but important point. If you have high blood pressure and you're not checking it in between doctor visits, talk with your doctor. Many experts believe that HBP monitoring is an important part of treating high blood pressure.
Home Blood Pressure Monitors
There are lots of HBP monitors to choose from And many are both easy to use and affordable. Most are validated for accuracy and precision prior to marketing. If you're thinking of purchasing one soon, be sure to purchase a monitor with a cuff that goes around your upper arm rather than one that goes around your wrist. The results are much more accurate.
And remember, the cuff size matters. Using too large or small a cuff can result in inaccurate readings. The size is based on your arm measurement. Most BP cuffs have the size printed right on the cuff, so it's pretty easy to find. Many HBP monitors offer more than one size cuff, either with the original purchase or as an accessory. Keep in mind, too, that your arm size might change over the years, so check the cuff size periodically. Have you been trying to lose weight? Your arm might get smaller. Trying to lose but gaining instead? Your arm might get larger. Take a look at the cuff you're using to be sure it's the right size for you.
As soon as possible after you purchase it, check the monitor for accuracy.. Take it to your pharmacy or doctor's office. First, use your monitor to measure your blood pressure, then have them use their equipment to do the same. You may need to take more than one reading with each set of equipment at 30 second intervals to be sure results are comparable. This procedure allows your healthcare professional to 1) make sure you're using your equipment correctly and 2) assess the accuracy of your monitor's results. Differences of a few points are typical and okay, but if the numbers are quite different, or if your monitor gives inconsistent results, you may need to contact the manufacturer.
Great article, Betty!
Here are a few more tips that I share with my patients who are referred to our blood pressure clinic:
1. Posture is important. When measuring your blood pressure, sit upright (preferably with back supported by chair), with feet flat on the floor, and your arm resting on a surface approximately at heart level. If your body is reclined, or your arm is hanging low, this may affect your BP reading.
2. Your BP fluctuate naturally throughout the day, which means your BP in the morning may be significantly different than it is later in the day (especially after physical activity, stress, sodium in meals, etc…). So, if your morning BP reads 110/70, and your evening BP reads 125/80, this is not that unusual. Try to be consistent with the time of the day that you check your BP.
Readers, please share any additional questions you may have with us!
Thanks for that great advice Alan!
Thanks for this article. As I’ve gotten older, I’m starting to pay more attention to my health.
I pulled out my BPM and tested 145/73 with a pulse of 80. The manual that came with the device states “Blood pressure is too high if at rest, your diastolic pressure is above 100mmHg and/or the systolic blood pressure is over 160mmHg”. However, they go on to say “Should the systolic blood pressure values lie between 140mmHg and 159mmHg and/or the diastolic blood pressure values lie between 90mmHg and 99mmHg consult your doctor”. Seems to be conflicting information but they do specify “at rest” in the first case. Since I just got done watching TV, I assume I’m at rest??? I had my vision tested this week and they tested my blood pressure. I was told my blood pressure was slightly elevated.
I would like to see a follow up to this article on what we need to do to control our BP better. I exercise regularly but my diet could use some work.
So great to hear from you Tony!
It sounds like maybe that brochure was published before the guidelines were changed in 2017, since the threshold of concern is more at the 140/90 range than the newer 120/80 range. But yes, I agree, their meaning isn’t real clear.. Did it say to recheck the measurement if it was more than 160/100 and then call the doctor if it was still that high?
Also, you’re right about the meaning of “at rest”. Basically as relaxed as you can be. If you were watching a thriller, maybe that’s not relaxed, so I’ll leave that determination up to you! But also take a look at Alan’s comments regarding posture which can make a big difference too.
I like your idea of writing on ways to bring blood pressure down that don’t involve medications. Thanks for the suggestion!
Sorry for the late reply. I just tested 132/76, better than the last time. The manual says to compare the device readings to the readings from a pharmacist, lol. I would hope that any pharmacists machines are calibrated regularly.
The manual for my device does specify normal as <120 systolic and 120. It also shows that reduction of fatty foods and salt may help lower the BP. I’ll try to adhere to that
Good to know that your manual is giving you the most up-to-date information. Alan and I are hoping to write another post soon with some more information on handling high blood pressure readings.