←back to thread

Commonly used arm positions can overestimate blood pressure readings: study

(medicalxpress.com)
330 points wglb | 3 comments | 14 Oct 24 17:57 UTC | HN request time: 0s | source
Show context
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.?

replies(18): >>41841065 #>>41841066 #>>41841097 #>>41841378 #>>41841596 #>>41842242 #>>41842355 #>>41842512 #>>41842978 #>>41842987 #>>41843132 #>>41843291 #>>41843843 #>>41843882 #>>41844009 #>>41844704 #>>41845158 #>>41848507 #
arcticbull ◴[14 Oct 24 22:46 UTC] No.41842987[source]▶
Also doctors and nurses are known to do an abject awful job of measuring bp according to the defined procedure. It’s usually way off when taken clinically.

Ars article here but there’s plenty in pubmed too.

https://arstechnica.com/health/2024/10/your-doctors-office-c...

[edit] The prep guidance is…

> You must not eat, drink, exercise, or smoke within 30 minutes of a reading. You must have an empty bladder. You must sit straight up in a chair with back support. Your legs must be uncrossed and your feet must be flat on the ground. The arm to be measured must be rested on a flat surface so that it is at the same level as your heart, not lower, not higher. You must sit calmly, without talking for five minutes to relax before the reading. When it's time, an appropriately sized cuff should be wrapped around your bare upper arm, right above the elbow; it should never be wrapped over clothing. At least two readings should be taken, with the average recorded. Ideally, readings should be taken in both arms, with the highest readings recorded.

When was the last time you got it measured properly? Literally never for me in a clinical setting. I don’t know why they bother honestly.

replies(4): >>41843105 #>>41843506 #>>41843870 #>>41843922 #
1. from-nibly ◴[15 Oct 24 01:09 UTC] No.41843922[source]▶
What's the point of taking your blood pressure if doing any of these things causes significant variance? I'm not meditating at home or out and about all day. So why does it matter what my blood pressure is in one single state? What if I'm in an elevated state all the time? What if I never am? It makes it really hard to believe that blood pressure readings are anything more than nonsense.
replies(2): >>41844025 #>>41848709 #
2. arcticbull ◴[15 Oct 24 01:26 UTC] No.41844025[source]▶
If you're doing a double leg press (especially in conjunction with a Valsalva maneuver) you can get an instant BP reading as high as 320/250. If that's your idle BP then you're not long for this world lol.

If your BP - measured in a specific and consistent set of conditions - is elevated vs baseline then you are at an increased risk for a set of medical conditions. Researchers could have picked any set of conditions to establish that baseline but I assume that idle is easier to standardize on than e.g. double leg press with 3 RIR. It's not which condition per se but rather that it's the condition researchers aligned on and studied.

The problem is that if the risk is established based on your deviation from the baseline, then you must be measured in the same conditions under which the baseline was established otherwise the results don't mean much if anything at all.

3. crazygringo ◴[15 Oct 24 14:02 UTC] No.41848709[source]▶
The idea, in theory, is to measure your "minimum" or baseline blood pressure.

That your activities throughout the day add variable amounts to the baseline but never go below it.

It is a very good question though -- some people have activities/jobs/lifestyles where their BP is significantly elevated all the time. So surely you would think that must matter?