I've dabbled a bit with it and it's very close to the cuff measurements.
It works by calibrating with their custom arm cuff device. I'd guess that it's correlating what the wrist sensor sees w.r.t. your wrist blood vessels and what the "true" reading is from your arm. You re-do the calibration every few weeks.
The device takes a reading every 20 or 30 minutes or so and seems to try to pick periods where you're more stationary.
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 isn't a bad thing, it just takes some getting used to since your "daily average" will be significantly above the readings you're used to if you're doing arm cuff measurements at the start/end of the day. Of course it's also getting readings at those more usual times too, but they get washed out in the larger number of data points from your day.
And goes without saying, your blood pressure SHOULD go up and down based on your activity and time of day. You just aren't used to seeing it other than at true rest.
But all in all it's been fascinating to see, and there's no doubt in my mind that this technology will be mainstream quickly (and Apple will likely dominate it).
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.
We already knew that things like weight fluctuated in normal people (periods, hydration, meals, etc), but many of us are still defaulting to the inaccurate model of slowly-changing measurements recorded 1x/2x a year at the doctor's office.
I'm sure people will get used to it, and many of the weight apps already wisely show averages to discourage fixating on individual measurements, but it feels like a missed opportunity.
Chicken and egg situation, no?
People are advised not to use those devices because there isn't much data about them for otherwise healthy people. But if they don't use those devices, there won't be much data.
This is a great point. Blood pressure readings are only useful in the context of stationary measurements under known conditions. Blood pressure is inherently volatile and depends on activity and recent movements, or to extreme events like cold exposure.
There are even finger-cuff blood pressure monitors designed for continuous, constant blood pressure measurement in the context of a lab or hospital setting. Their measurements would be useless in the context of someone moving around all day, but it can be useful in the context of someone under anesthesia or undergoing a controlled lab test.
This isn't fully true. For clinical reference to known "good" number ranges, then yes, you want to make the comparison as accurate as possible.
Butm there's a lot of potential unlocked with more data.
For example, we could discover that daily BP averages are more predictive than isolated doctor's office measurements. Imagine two people with equal BP measures at the doc's, but one has a more stressful job with higher average BP. We might reasonably expect them to have worse cardiac outcomes. Or consider the person who's anxious about docs and consistently shows higher numbers in the office than outside; we'd expect the reverse!
Another factor might be examining the variance. This already has precedents, since we know there are things that heart rate variability (HRV) correlate with more strongly than heart rate itself.
I was really hoping Apple was going to bring BP to the watch this year, but my guess is the regular external calibration requirement is too much for their plug-and-play philosophy.
Regular external calibration helped me build confidence. I was suspicions if the watch worked, and how well it worked. Calibration is every month - it expires. I take 3 measurements in parallel watch-cuff, and tell the watch App what the cuff measured. I didn't mind it initially. I now find it annoying tbh. I see why Apple would like to get rid of it. Post calibration, I measure 3 times in parallel both watch and cuff to check if they match. If the difference is within 5% - then fine. In 3 years it's happened twice where they differed more and I had to recalibrate. From recollection - both times with a reason, a TV was turned on in living room.
I have the impression that BP measurements differ though the day (lower in the morning, higher in the evening), depending on activity or at rest of course, I think there maybe some seasonality too (winter v.s. summer). Measuring BP when going to the doctor once a year strikes me as a wholly inadequate. If the BP is absurdly high out of normal range - then yeah, we learn something is wrong with the patient. But in any other case - don't see what can be deduced from 1 random measurement.
To check if the calibration is important, I had my wife use the watch, that is calibrated on me. She got absurd readings. So yes - the calibration is important and is tied to the person that did the calibration. (edited to add this)
I am particularly excited about the UT Austin research[1] that used conductive temporary tattoos to get actual real time data and not just polling at intervals. However it’s not yet at the stage of commercialization and the design is more the width of a cuff than a watch.
[1] https://scitechdaily.com/electronic-tattoo-offers-highly-acc...
Given enough data pairing continuous blood pressure with major events like heart attacks and strokes, we may even develop more accurate models to predict which types of spikes create the most cardiovascular risk.
As I typed the above sentence out, I thought "why not both?". Use the technology to reduce your risk, but in the event that the bad event still happens the notification could save your life.
There was a huge effect from perceived temperature--while I didn't do the cold plunge I got some quite high readings when I was on the chilly side. Yet I could get low-normal readings with my heart rate above 130 which is the highest I could go at that elevation. Obviously I couldn't actually take a reading while moving but I could have it on my wrist, stop and immediately press the button. The pattern I observed was activity raises temperature which lowers blood pressure.
My particular BP scenario is good diastolic, high systolic but low rest heart rate (low 50s). My pet theory is that my heart does fewer but stronger pumps, which increases the BP. After exercising, when heart rate remains elevated, the BP is lower since the heart is doing more frequent but less powerful beats.
Just a pet theory, I haven't even discussed it with a medical professional.
Do you or anyone you know happen to have firsthand experience with the device?
BP remains a great mystery to me, even with the device. My cardio fitness is pretty good despite carrying a few extra pounds (I'm in the low 50s for resting heart rate), and while overnight I dip down in the 120's, I can see it shoot up based on various things like cold plunge, caffeine, exercise (during), etc. I can also see it drop temporarily (hot tub, meditation, the hours FOLLOWING intense exercise, etc).
I had many pet theories through the years - that I had white coat syndrome, that I disliked the feeling of the cuff, etc etc. But the device showed me that, no, something really is going on independent of these pseudo-causes.
BTW water retention seems to play a big role. When I did keto, which causes a big drop in water retention, my BP also went down. Strange. Supplements have an impact too.
All this to say - get the device and see for yourself, but you might find yourself in the same place I am - which is that you have much better understanding of what's going on in terms of symptoms but are still on the search for "the underlying cause" if there even is such a thing.
There's no obvious cause, I'm fit and healthy in all other ways, I've had multiple blood tests and ECGs, my cholesterol is normal, everything is normal, just the blood pressure. I also didn't know about this machine but I might get one. I have developed anxiety around having it taken (because of the experience of getting sent to hospital!) so it goes up when I take it, like extreme white-coat syndrome.
I'm definitely getting one of these gadgets so I can see what it really is, without the stress and pain (those things hurt!) of inflating cuffs.
It would mean that you can literally show that working conditions are shortening your life.
Your company's health insurance could look at BP during commuting hours and in the office vs. at home and raise rates on companies based on their policies.
But having worked in medical sensors, and spending time with researchers as customers, there was a real sense that they could learn a lot from BP readings that were accurate and continuous.
I wonder if you're calibrating on a supported arm, then letting your arm swing free later with the wrist device.
Looks interesting, but it too _requires_ a cloud account to function. WTH.
Yeah, people panic reading a single 150 systolic, yet routinely it can reach 220+ during heavy exercise. It's perfectly fine. The health metric is the BP at rest, i.e. how low it goes when you're completely idle.
I find it takes up to 20 minutes to reach its lowest sometimes, in state of absolute calm: no movement, no talking, no anxiety. Hence the 'white collar hypertension', i.e. high BP when measured in hospitals and GPs office, where they don't give you enough time to settle down, or are not spaces that induce calm mental states.
The way I take my BP reading is every 5 minutes, until I get a similar reading after 2 consecutive measurements. It takes longer than you'd expect.
Did I eat late before bed? Higher BP overnight. Drink any alcohol at all after, say, 12pm? Higher BP overnight. So it's still useful and interesting to see the overnight values change and shift around.
However, the contrarian in my mind says that it's not smart to ONLY pay attention to your deep rest state BP, since that only applies to a fraction of the day. And if you're running around at high values for the rest of the day, you're still potentially doing damage to your kidneys, retinas, etc - the sensitive blood vessel stuff.
So it's a useful device, it's useful to have the data, but it's also still a bit of black box.
The fact that 80% of all high blood pressure is of unknown physiological cause is a real head scratcher considering that cardiac misadventures are the leading cause of death in the Western world.
Like many things, it is diet related. It seems "unknown" because GPs are still lagging well behind modern dietary research and are often nothing more than pill pushers. Lowering your sugar and simple carb intake over the long term, and fixing potentially hidden metabolic syndrome (see skinny fat people with unhealthy livers) is how you reverse it.
So while this may explain some amount (perhaps most?) of peoples idiopathic/essential HBP I doubt it's that simple.
"It's your potassium levels", "it's your homocysteine levels", "it's your fructose", "it's white-coat syndrome", "it's...." etc. Surely we're making progress but it's also not a silver bullet thing.
Good thing the treatments are so safe and effective.
Labile hypertension is the most difficult to treat. So far my heart is perfect for a late 50's dude. Just had an colorflow echocardiogram, no sign of hypertension in the heart. Probably because I eat so much fish.
If I drink coffee my BP is up all day though. I am just very sensitive.
I really freak out about getting my blood pressure taken in a clinical setting, it's really unusual.
I had some treatment for a kidney stone recently, and after the procedure they were checking me with some pretty accurate machines, like 10 times in 24 hours (apparently), 128/80, for some reason in that specific setting I didn't freak out.
White coat HT is a weird thing.
Wonder if you have noticed if you were neurologically sensitive to any types of foods?
I'm learning I just can't really do coffee / caffeine though, I don't think it's ever really been good for me, it causes reflux and anxiety for me, but I just loved coffee to much. I gave up recently however!
You might have heart burn occasionally too ?
[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.
If the increase in heart rate is large (>30bpm), especially when going from laying to standing, it could be a sign of underlying dysautonomia or POTS. If you experience symptoms (dizziness, fatigue, fainting, etc) it's worth getting evaluated. We (the OP) do offer medical care for POTS here: https://empirical.health/pots
As for the relationship between low heart rate and longer life spans, it's not necessarily causal -- a lower heart rate is often a sign of a stronger cardiac muscle (each beat pumps more blood, so fewer beats per minute are required to pump the same volume of blood). So I'd suspect much of the relationship here is driven by these confounding variables!
To answer your question, there have been an abundance of epidemiological studies showing that the drop in blood pressure is worth the slightly increased heart rate (assuming you’ve been diagnosed with hypertension). The main benefit is the drop in stroke risk, atherosclerosis, and kidney damage, even despite the fact that your heart has to beat faster.
My suspicion is that this happens because the heart is trying to maintain a constant oxygen supply to the muscles. However, if blood pressure is lowered by improving factors like arterial flexibility, stroke volume (amount of blood per heartbeat), muscle oxygen efficiency, or oxygen content in the blood, the heart wouldn't need to pump faster.
I’m not a doctor, but I don’t think this covers all cases. If someone has some kind of heart disease, they could have a lower resting heart rate and probably need medical attention and care. It may not imply that they’re going to live longer.
Too low heart rate can also be a problem.
talk to your cardiologist about your specifics.
At the population level, the guidelines have backed off over the last 20 years. What’s normal now used to be called high blood pressure.
Back when I took beta blockers they reduced my heart rate from 65-70 to 45-55.
Hypertension is correlated with a lot of issues, and it's easy to measure.
It's also easy to keep formulating novel chemicals, so keep complaining about side effects, and your physician will be happy to keep spinning the Formulary Roulette Wheel.
I am very sceptical PPG alone will be capable for many reasons. Aktiia does indeed have European regs clearance. But, they don't have FDA clearance. The FDA is a very different beast (more hands on - and they'll be absolutely much more heavy with such a new approach) - and they must have concerns on the approach for it to take this long. The FDA even has accelerated programmes for breakthrough high impact tech as they really do want it to get to market safely.
The main cuffless FDA cleared devices I know measure the pulse transit time betwen a central ECG patch and a peripheral based PPG (that time is then calibrated to a BP with the Moens Kourteweg equation) - see Biobeats watch and a now defunct wearable ICU monitor company I can't find the name of.
The issue with PPG is that it is wildly sensitive. The PPG waveform morphology will changed dramatically based on the pressure of the sensor against the skin, unconstrained changes in orientation of the human and arm etc. Changes in morphology != changes in system wide BP.
Speak to an anaesthesiologist and they'll tell you blood pressure is function many things eg cardiac output, stroke volume, heart rate, blood volume, total peripheral resistance etc etc (https://www.sharinginhealth.ca/multimedia/images/blood_press...). The question is whether PPG alone can measure all these things. I suspect it's really just measuring lots of proxies of all these things. And that's fine - however in the presence of people with conditions or on therapeutics that alter these in very personalised and unpredictable ways then error may start to creep in on free living measurement. Paradoxically, it's probably these people for whom this tech would have most impact - not the worried well.
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.
My experience with them is that although I wouldn't trust these to diagnose a medical condition, the trends are correct and correlate to cuff readings - they're not just random number generators.
I just wish there were a way to export the data from the H Band app. Apparently, the data is stored in SQLite files.
Sounds interesting. Any idea where can I find such, and additionally, how I can differentiate from the ones with fake claims?
And, of course, you have the fact that the American College of Cardiology (ACC) updated their blood pressure guidelines in 2017 to use a lower threshold. So some people with moderately high blood pressure would now be considered to have hypertension and are recommended to seek treatment.
https://www.ahajournals.org/doi/pdf/10.1161/HYPERTENSIONAHA....
24 hour ambulatory BP measurements are the gold standard for accurate HT dxs.
I have a blood pressure monitor that takes the lowest of three measurements. It's really annoying to use, takes forever, feels uncomfortable, and my blood pressure often drops another 10 points if I do it all over again because I've been laying in the bed another 5min.
Passive measurements address all of this. You also get to see what activities have what impact on your blood pressure. How does your daily blood pressure graph look like on and off ADHD meds, for example?
I can't wait until this info is part of the wrist wearable kit.
“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.
I'm unfamiliar with this abbreviation but did my best with Google. Does it mean 'hypertension diagnoses'?
I'm interested in what the future holds when these things are capable of FDA-approved diagnosing. Will Apple send a prescription for BP meds to my pharmacy?
Fast forward 9 months, and I'm now using my Galaxy Ultra watch to monitor my blood pressure, and I've been able to reverse hyper tension thanks in part to how much of an improvement it has made when it comes to quickly getting the pressure reading.
Compared to the Omron I calibrate it against, it's a far better experience. It's also a huge step up in performance over the 6 Classic that I upgraded from. That one would have a failed reading 3 times out of 4, whereas the Ultra gets it right just about every single time.
The biggest pain is the monthly calibration process, seriously it feels like if I bat an eyelid, or not have the cuff on with just the right tightness, or just have the arm at a slightly different angle, or just get anxious about this whole thing, the Omron (a modern unit with built in Bluetooth etc) will give a different reading. When I get the process done right, however, the Galaxy will return readings that are very close to the Omron both systolic and diastolic - and then it's a month until next time.
Being able to quickly and easily get my blood pressure in a number of different situations made a huge change in my motivation to get it under control; I primarily focused on diet and exercise. I ran/run the test several times per day, and learned so much from it. Absolutely love my Ultra watch, it looks gorgeous and performs amazing in general as well.
Fwiw I'd regularly see values like 140-155 over 90, now I'm typically around 120 over 80 give or take.
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.
I used to work at Higi which has many blood pressure cuffs in public locations. I'm wondering if it's practical to calibrate a smartwatch sensor at one of these, or if it would take too long when you're grocery shopping or at the pharmacy.
I'm also wondering if new generation cuffs are required. The cuffs we used would be pretty old at this point.
1. Most clearances only apply to when people are motionless. 2. Often need to calibrate frequently. 3. No practitioner knows what to do with continuous bp data even if they had it.
Solve those and we’ve got something big. Until then progress is welcome but not revolutionary.
Anyways, I stopped looking at it, and I only use it for the looks and to show me notifications.
Side note: please fix your header. Makes the website appear so much less professional than the information it provides really is.
Several years ago, I got an omron wrist cuff blood pressure monitor. Some doctors showed heavy skepticism at the time but I've never seen any reason to think it's inaccurate when properly mounted and with healthy batteries.
I had a sleep study done last year using a brand new machine the lab got (literally unboxed while I was there) that uses a combination of the ecg signals and pulse timing to calculate blood pressure continuously once calibrated. Seemed pretty cool to me and I got the impression this technique is fairly new?
What I found was the wrist cuff was incredibly sensitive to both positioning and to any movement, it was harder to get a consistent reading.
