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The science behind on-the-wrist blood pressure tracking

empirical.health

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Re: The science behind on-the-wrist blood pressure tracking

#21

Post by throwup238 »

corry wrote: post #4

Actually, there is a wrist device called "Aktiia" that's approved for use for continuous BP monitoring with clinical accuracy by the UK and German health authorities (I believe). It's a bit of a pain to get over the pond, but with a shipment-forwarding company + a UK App Store account you can get up and running. I've dabbled a bit with it and it's very close to the cuff measurements. It works by calibrating with thei…

> However, one thing to be aware of is that you are not used to seeing your BP readings from the entire day.

Same thing with those continuous glucose monitors that almost anyone can get and put on their arm now. The vast majority of the data and recommendations we have are for diabetics using regular single use measurements or a proper glucose tolerance test so shortly after the user eats a bowl of rice while wearing it, it sends them into a hypochondriac spiral when they see a peak of 200. Their doctor generally has to talk them down. There's just not that much data on what the average healthy person's response to blood sugar is, especially when it's continuously monitored.

Re: The science behind on-the-wrist blood pressure tracking

#22

Post by nradov »

Aurornis wrote: post #14
corry wrote: post #4

Actually, there is a wrist device called "Aktiia" that's approved for use for continuous BP monitoring with clinical accuracy by the UK and German health authorities (I believe). It's a bit of a pain to get over the pond, but with a shipment-forwarding company + a UK App Store account you can get up and running. I've dabbled a bit with it and it's very close to the cuff measurements. It works by calibrating with thei…

> However, one thing to be aware of is that you are not used to seeing your BP readings from the entire day. Did you jump in a cold plunge 10 minutes before it ran? Get ready to see a really high reading dot in the 'danger zone'. Went for a jog and are catching your breath on a park bench? High dot. This is a great point. Blood pressure readings are only useful in the context of stationary measurements under known co…

Anecdotally I find my blood pressure (measured with a regular upper-arm cuff while sitting) to often be lowest soon after completing a workout, like a hard 5K run outside. I'm not sure why, maybe the vasodilation effect from increased nitric oxide production?

Re: The science behind on-the-wrist blood pressure tracking

#23

Post by wil421 »

kbrisso wrote: post #3

Measuring blood pressure on the wrist is tricky. I usually do three measurements to get an accurate reading. I have two machines I use. The older one is actually better than the new one. Another thing is, pay attention to how you feel. I can feel my blood pressure when it's high and usually know when the device reading is off. I do this because my family has a history of high blood pressure and so far because of life…

Why do you have to do it so often? Why do you even do it if you’re not on meds? Third, what would you even do if it’s high?

Re: The science behind on-the-wrist blood pressure tracking

#24

Post by wil421 »

oidar wrote: post #5

I would love to have continuous BP monitoring. I ready for this tech to mature. I'd wager that blood pressure varies way more during the day than weight (which can vary as much as 5 lbs or more) - and continuous, easy BP monitoring at would cause HT dxs to drop significantly.

The problem with this is exercise messes with blood pressure.

“Extremely high blood pressure elevations of up to 345/245 mmHg were observed during the lifts.”[1]

My doc even said it can get as high as 400 and it’s important to breathe correctly.

[1]https://pubmed.ncbi.nlm.nih.gov/2632751/

Re: The science behind on-the-wrist blood pressure tracking

#25

Post by daemonk »

For most instruments, it's an interplay between resolution and consistency. There isn't a "true" reading in any sense of the word. There is just how much resolution you are measuring and how consistent the measurement is between independent readings of the same event.

The overwhelming amount of pre-existing clinical data gathered by cuff-monitors means that any novel measurement methods benefit from tying/correlating their output to the existing data for compatibility. It's a bit unfortunate in some sense as cuff-monitor data lacks resolution and sometimes can be a bit of a drag on novelty.

Re: The science behind on-the-wrist blood pressure tracking

#26

Post by mysterypie »

I'm hoping someone can answer a question that's been bugging me for years: When I take blood pressure medication my blood pressure goes down but my heart rate goes up[1]. That can't be good. Heart rate has a strong inverse correlation with lifespan, and this even holds across species (animals with higher heart rates have shorter lifespans). So does lowering blood pressure reduce the risk of heart disease, stroke, etc, but nevertheless shorten your lifespan in other ways because of a higher heart rate?

[1] I've verified this for myself with careful record keeping over long periods of starting/stopping different BP meds, but I'm not entirely sure it's true for everyone.

Re: The science behind on-the-wrist blood pressure tracking

#27

Post by lispisok »

oidar wrote: post #5

I would love to have continuous BP monitoring. I ready for this tech to mature. I'd wager that blood pressure varies way more during the day than weight (which can vary as much as 5 lbs or more) - and continuous, easy BP monitoring at would cause HT dxs to drop significantly.

High blood pressure has been defined as blood pressure over a certain threshold when blood pressure is taken a certain way. That certain way is at rest when it's lower than moving around. All the data and research has correlated health outcomes that way. We already know blood pressure is higher when you are up and about than after you've been sitting down for 5 minutes. If you're trying to get out of your hypertension diagnosis using continuous monitoring you are in for disappointment because hypertension has been defined by your blood pressure when it's at its lowest.

Re: The science behind on-the-wrist blood pressure tracking

#28

Post by CookieCrisp »

mysterypie wrote: post #26

I'm hoping someone can answer a question that's been bugging me for years: When I take blood pressure medication my blood pressure goes down but my heart rate goes up [1]. That can't be good. Heart rate has a strong inverse correlation with lifespan, and this even holds across species (animals with higher heart rates have shorter lifespans). So does lowering blood pressure reduce the risk of heart disease, stroke, et…

My understanding of the heart rate correlation to lifespan between different species is that it is “within a couple levels of magnitude” and that an increase of 10% in a human’s rate does not correlate at all to a 10% decrease in lifespan

Re: The science behind on-the-wrist blood pressure tracking

#29

Post by Aerroon »

mysterypie wrote: post #26

I'm hoping someone can answer a question that's been bugging me for years: When I take blood pressure medication my blood pressure goes down but my heart rate goes up [1]. That can't be good. Heart rate has a strong inverse correlation with lifespan, and this even holds across species (animals with higher heart rates have shorter lifespans). So does lowering blood pressure reduce the risk of heart disease, stroke, et…

Have you mentioned this to your doctor? There are different types of blood pressure medications. Some will lower your heart rate.

Back when I took beta blockers they reduced my heart rate from 65-70 to 45-55.

Re: The science behind on-the-wrist blood pressure tracking

#30

Post by saltcured »

stewh_eng wrote: post #10

I'm a med device engineer and have watched the hopes and dreams of cuffless BP monitoring tech. I hope we get there as it will be hugely important. However, remember tech is only a small part of the battle. We need to figure out clinically what to do with all this new continuous data. I am very sceptical PPG alone will be capable for many reasons. Aktiia does indeed have European regs clearance. But, they don't have…

I wonder if you've heard of the Resonance Sonomanometry method claimed by Esperto Medical https://esperto.health/ and how you think this compares to others.

It seems like it might be an ultrasonic method? They claim no calibration needed, but I don't know if it is tolerant to movement and posture.

I can also imagine this might be too power intensive to put in a smartwatch form factor. Maybe more of a bedside or clinical device...

Disclaimer: I had past contact with some of their researchers in a different bioimaging domain. I don't know anything more about this venture than it says on the website.

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