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Commonly used arm positions can overestimate blood pressure readings: study

(medicalxpress.com)
330 points wglb | 9 comments | 14 Oct 24 17:57 UTC | HN request time: 0.63s | source | bottom
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crazygringo ◴[14 Oct 24 19:30 UTC] No.41841006[source]▶
There's definitely a huge variance in blood pressure readings depending on posture, relaxation, arm position, recent activity, etc. If you buy a blood pressure monitor, it's really interesting to see how "random" a single reading at the doctors' is, and how large your fluctuation throughout the day is.

That being said, it really makes me wonder about studies that correlate blood pressure with other things. Is the blood pressure really being measured "correctly" in all those studies? Or not?

In other words, if your "true correct" blood pressure is lower than what the doctor normally takes, but then a lot of the studies are based on real-life "incorrect" higher blood pressures, then don't you similarly want an "incorrect" higher reading for consistency? Or are the studies always really done with far more accurate blood pressure readings, where the patient sits still for 5 min beforehand, keeps their legs uncrossed, is totally free of stress and anxiety, didn't exercise beforehand, etc.?

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gklitz ◴[14 Oct 24 19:38 UTC] No.41841065[source]▶
> 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.

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1. hirvi74 ◴[14 Oct 24 22:18 UTC] No.41842679[source]▶
> 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.

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2. devilbunny ◴[14 Oct 24 22:22 UTC] No.41842732[source]▶
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.

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3. coatmatter ◴[14 Oct 24 23:54 UTC] No.41843509[source]▶
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".

4. telcal ◴[15 Oct 24 00:42 UTC] No.41843772[source]▶
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.
5. matheusmoreira ◴[15 Oct 24 03:26 UTC] No.41844612[source]▶
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.

6. raverbashing ◴[15 Oct 24 04:40 UTC] No.41845004[source]▶
Either it's accurate enough (most cases) or it is too wrong

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

7. bigmattystyles ◴[15 Oct 24 14:51 UTC] No.41849223[source]▶
And it has to be in retrograde.
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8. gklitz ◴[15 Oct 24 15:08 UTC] No.41849417[source]▶
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.
9. devilbunny ◴[15 Oct 24 22:59 UTC] No.41853986{3}[source]▶
That's a complicating factor, but one that we can usually calculate.