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 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).
I am wondering if continuous blood pressure monitoring would have some knock-on effects as a measurable, correlatable negative health effect of stress.
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.
> 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.
> 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 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.
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?
I found the exact reverse with the jog. One day I went into the mountains with a cuff on my wrist and took a bunch of measurements. I wasn't jogging but I had something like 25 pounds on my back and was definitely pushing myself.
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.
IIRC there's also a Samsung Galaxy Watch that does blood pressure monitoring, with similar requirements. Have to work a bit to get the app installed in the US, but then it takes periodic measurements, is fairly accurate, and requires calibration once a month.
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.
Are the sensors already capable of it? Maybe someone could make a third party app for the watch
Was unaware of the Aktiia. Thank you for posting. I saw firsthand how CGM changed my behavior and would love the same for ketones and blood pressure.
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...
This is super exciting, thanks for posting! I developed high blood pressure after Covid and have done a few 24h studies to better understand it. The traditional machines are super bulky, essentially like carrying a regular BP monitor around with a pouch that's strapped to you, maybe just a bit smaller. All in all it's far from convenient and can kick in at inopportune times. Having around the clock insights would hopefully give me a better understanding of the condition. For context, I've jumped through all sorts of specialty doctor hoops and there is no known underlying cause outside of the fact that it just showed up after Covid.
Do you or anyone you know happen to have firsthand experience with the device?
I've found similar. I don't know if it was post-Covid, but I have completely asymptomatic high blood pressure. It's really scary to go to the doctor for an extremely routine health check expecting to be back at work in an hour, and then suddenly be told that your blood pressure is so high that you need to go to hospital immediately.
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.
I'll bet blood pressure readings throughout the day will be analogous to the data we get from CGMs (continuous glucose monitors). You get lots of spikes during the day.
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.
> 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.
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.
During a recent visit, I mentioned my "White Coat Syndrome" was probably affecting me right there, so they selected their most attractive woman with the best perfume and a manual sphygmomanometer for a hands-on measurement, before releasing me.
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.
This sounds like reflex tachycardia -- your body wants to ensure blood is flowing to all the right places, so it raises heart rate to partially compensate for blood pressure falling. Reflex tachycardia can be a normal response to certain types of blood pressure medications, like vasodilators or diuretics. Beta blockers are a different common type of blood pressure medication that attempt to lower both blood pressure and heart rate simultaneously.
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!
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
It’s pretty normal for heart rate to increase with a drop in blood pressure. It’s part of a normal reflex called the baroreceptor reflex that your body evolved to keep you alive.
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.
I'm not a doctor, but my understanding is that lower blood pressure can indeed lead to a higher heart rate under certain circumstances. For instance, people taking minoxidil for hair loss can experience lower blood pressure, which leads to higher heart rates and increased left ventricle thickness as a side effect.
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.
It’s complicated. You need blood pressure to live…
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.
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.
It's the futility of trying to make two arbitrary numbers go down and covering up a mere symptom.
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.
Yeah -- in addition to inappropriate measurement technique, "white coat hypertension" can cause elevated blood pressure readings.
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.
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 lifestyle choices I have avoided the need for meds.
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?
I don't check my blood pressure every day. Maybe twice a month or when I feel like crap. I also check my glucose. Why? I believe if I keep myself in check I will keep myself out of the hospital as I age. High blood pressure and diabetes are two things I can manage. I don't want to be on meds unless I absolutely have to. Exercise and these tools allow me to figure out what I can eat and not. I'm not obsessed with my health or a health "nut". The upside is I don't get sick that much and feel good.
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/
Yes, BP is much higher when exercising, but presumably in these situations the user will indicate that they are exercising in whatever app they are syncing with. 24 hour ambulatory BP measurement protocol directs pts to not exercise during the time to rule out this confounding factor.
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.
Well, baked into your own claim, they don't have hypertension if their pressure is only elevated when it's taken (e.g. the doctor's office) rather than what it might drop to otherwise.
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.
If you look at the BP measurement protocol for HT dx, most people will never have a visit that matches that protocol because it costs a lot of time and time is something medical practices don't like to give for something as simple as HT dx.
https://www.ahajournals.org/doi/pdf/10.1161/HYPERTENSIONAHA....
24 hour ambulatory BP measurements are the gold standard for accurate HT dxs.
> HT dxs
I'm unfamiliar with this abbreviation but did my best with Google. Does it mean 'hypertension diagnoses'?
Why do you think this would cause HT diagnosis to drop? If anything all of these continuous monitors create more patient visits and probably more diagnosis.
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?
I think there is a lot of white coat HT that makes up many cases. I think the ACS recommends a measurement 3 times in a row at different office visits. So, maybe anxiety might be a direct cause of HT dx.
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.
Haven’t read the article yet but there are three big things that hinder the usefulness of this tech as it stands:
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.
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 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.
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.
That's the one! They were lightyears ahead but seemingly couldn't make the commercials work. Thank you!
I am fascinated by the concept of blood pressure as one of the foremost tools of health. Can someone recommend perhaps a book size read on the history of how we came to learn of its value and help illuminate well... what it even is?
Side note, I started monitoring with a cuff-style monitor over the past month, and one thing that’s super important is keeping the cuff at about heart level. The cuff I got actually reminds you of this verbally. While it obviously makes sense, it’s a bit surprising how much a change in elevation affects the readings.
Try sticking it around your ankle and measuring while standing up. I get 250 mmHg systolic, easily
Great read.
Side note: please fix your header. Makes the website appear so much less professional than the information it provides really is.
Thanks! Would you be able to send me a screenshot of what you're seeing? It may be formatting differently on your screen than mine. bmb@empirical.health.
Two tidbits from me:
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?
