Commonly used arm positions can overestimate blood pressure readings: study

> Is the blood pressure really being measured "correctly" in all those studies? Or not?

This is why you do readings three different times a day for several days. And why there’s instructions on how long to dust still before the readings, why you do three repeats with multiple minutes of wait in between, and finally why the averages of those readings aren’t just simple averages. But yes you always have to wonder about every study using self reported home readings if they follow the instructions or not, because it is tedious to do it correctly.

The reading process itself is a constant that you can't filter out by doing it repeatedly. Something squeezing your arm with what feels like the force of a hydraulic press surely doesn't have any weird side effects.

Anecdata, but I always get high anxiety from not being sure if the thing is actually still working properly or if it's just gonna keep pumping itself up until it explodes in my face or something. Not exactly rational but these sort of things never are. Looney toons ass machine.

"Something squeezing your arm with what feels like the force of a hydraulic press"

It shouldn't feel that crushing. I know it's common, but it shouldn't be. It's lazy/rushed healthcare professionals who only want to take it one time suing an automated machine and crank it to 200mm. If you actually put it at 140mm or take it with a manual sphig, it would read a "normal" person just fine without the crushing. The problem is, the people who are high around 130-140 need the machine at least 20mm higher and would need a retake, which means more time.

I have an automatic at-home blood pressure device, and it does the same thing. Not 200 mmHg, but high enough that I’d freak out if I didn’t know it was normal and would let up soon enough[1]. Did the product designers do that intentionally while still meeting a spec of “not panicking the user in a way that would elevate blood pressure” and getting approved for sale to non-professionals?

It seems like this is genuinely hard to work around in practice.

[1] I recall it being a staple of 80/90s tv, at least Beavis and Butthead, to have a character use an auto blood pressure device and freak out at being so clamped.

There might be a repeatability thing. Always give the full pressure then at least it's one less variable to account for.

Nah. Modern automatic cuffs are adaptive. They tend to first run up pretty low (like 150), see if there is signal. If not then they have to inflate more and more. They tend to determine where to start next time based on the last reading, so if it had the go up to 200 for the last reading it’ll start there next time. If the cuff is a vise, excluding operator error the most likely cause is actually having high blood pressure.

Just to point, it's known that a sizeable segment of the population reacts to the pressure measuring process with increased blood pressure.

One alternative is a cuff that measures on the upswing, rather than the downswing. It does not tend to squeeze quite as hard, because it stops as soon as it has the systolic reading.

e.g. Omron BP7000

> This is why you do readings three different times a day for several days.

What good is this if my monitor is not as accurate as the one at a doctor's office? It's not like my doctor would take my monitor's readings over his.

You might be surprised. "White coat hypertension" is well-known. Someone with a reliable set of readings from home would be more convincing than someone who says "I get it read at Walmart/CVS once a month and it's ok".

Your doctor's office's monitor isn't incredibly accurate. If you want accurate, you need a mercury sphygmomanometer to measure the pressure. Unless fundamental properties of the universe have changed, it will also be comparable to any other readings taken with mercury.

Find one that is accurate enough and crosscheck it with the one at the doctor by taking regular measurements so you get an idea of trends rather than absolute values. Doctors do know about white coat hypertension - it's not a myth. There's no reason you can't do your own experiments with consumer-level blood pressure monitors from reputable manufacturers. In fact, it was my mother's primary care provider who recommended she buy one for home use.

This is what I did with a US$10 pulse oximeter (a Contec CMS50M from China) when my dad ended up in ICU last year, and it was pretty much bang-on with its readings. I've also tested my pulse oximeter on plane trips and know it will drop below 90% when the air is thin (and rise up again if I do some deep breathing), and therefore know it isn't always stuck at a high value.

Search PubMed for "The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by the Food and Drug Administration: The Possible Global Public Health Implications".

My doctor did. My blood pressure was slightly elevated in his office and I said it happens at every doctor. He said to get a home monitor, test 3 times in the morning, 3 times in the afternoon for a week and bring in the results at the next appt.

I have a 6-7 year old Omron brand device that doesn't do this. I can always tell right away when my BP is running high because I can feel the machine squeezing harder than normal to get the reading.

There is another factor that everyone is ignoring here. Some people are just much more sensitive to that kind of pain. If you Lymphadema, or especially Lipodemia, you are much more likely to experience a lot of pain even when a manual sphygmomanometer is being used.

The Omron BP7000 doesn’t hurt me that much, and I measure mine every morning and every evening. But it does hurt my wife, and she has both conditions.

Don't worry, your monitor is good enough for the purpose of screening for hypertension. Truth is the exact values don't matter much for this purpose. Only thing that matters is the fact that people die less and develop less complications when treated based on the results. They are still useful even if the figures have some error in them.

Medicine is just statistics.

Either it's accurate enough (most cases) or it is too wrong

Unless it's a wrist model, it should be ok.

I have omron it has been at least 10 points lower then my other ihealth cuff. I even sent it in, they said was fine. Had the dr check it as well. It was always 10 points lower. I read that omron measures differently than the typical bpm.

And it has to be in retrograde.

That anxiety is more present in the first of the readings than the last, so you get an indication if that’s affecting the reading too. You don’t have to be able to filter it out entirely to know if the reading has diagnostic value.

It varies of cause, but here the doctor just sends you home with a monitor exactly identical to the one they use at the office. But it’s not like there’s a world of difference to the ones you could buy yourself at a resonable cost.

To my knowledge Omron is considered one of the gold standards for home BP monitoring. Most of their cuffs measure the same old way, the BP7000 is one of the few models that do an upswing measurement. I've had both, along with periodic measurements at the doctor (I also do not get white coat hypertension). The Omrons have been in agreement with all my "official" measurements.

That's a complicating factor, but one that we can usually calculate.

I would trust the self-reported home readings more than those taken by professionals, because they're probably happening more often and under less stressful and exceptional circumstances.