I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours
97 comments
·November 11, 2025alina_3339
szundi
[dead]
cestith
Regarding white coat hypertension, the shot isn’t always necessary. Some people’s blood pressure just goes up from the stress of the clinical setting.
saghm
My wife developed an autoimmune condition a few years ago that causes her to need to see a specialist every few months. For some reason, the hospital we've been going to uses these automated blood pressure readers that literally need to get wheeled around because they're four feet tall with a digital display, and during one of the early visits she had because of one of these conditions, the device bugged out or something and it kept squeezing her arm without releasing the pressure, and the person taking the reading didn't know how to disengage it manually and ran out of the room to go and find someone to help them without taking the time to rip off the velcro band on my wife's arm or anything. Ever since then, I literally get stressed every time my wife's blood pressure gets taken from one of those devices even though I'm not even the one who's getting measured!
wkjagt
I had a doc appointment a couple of weeks ago. My wife was driving and we were running late, so I was getting stressed about missing the appointment on top of being stressed about going to see the doctor. There was a lot of traffic so I decided to get out at a red light and run to my appointment while my wife parked the car. I only barely made it and the first thing they did was take my pressure. They took it twice, because at the first they were like, this can't be right. When I explained, they asked if I had a blood pressure monitor at home so I could take my own pressure at a more quiet moment.
pavel_lishin
I have an intense phobia of dentists; if I were wearing a constant monitor, I bet you could tell when I was at the dentist just by watching the blood pressure and heart rate spikes. (You'd have to find some way of differentiating them from me being in a car accident, or being attacked by a werewolf.)
normie3000
Werewolf attacks usually fall on predictable dates, during night hours.
6LLvveMx2koXfwn
It's interesting that you have a baseline for 'being attacked by a werewolf'.
adastra22
You don’t??
gregdeon
I wonder if it would show up on the heart rate (or heart rate variability) tracking from an Apple Watch or similar. My Garmin picks up stressful events all the time.
kakacik
I have a mild fear of needles. Whenever my wife does acupuncture on me, I am quite uneasy in the beginning, looking away but still I end up covered in a bit of sweat till she finishes putting needles on all the points (and sometimes they are properly weird places I wouldn't imagine sticking tiny needle into... doesn't help). Don't monitor the heart rate/pressure but it must jump up significantly
alexfoo
White coast hypertension isn't just about a clinical setting, it's more generally about the worry about the results of having your BP measured. [EDIT] OK, well maybe there's another type of hypertension which is related to anxiety about a high result regardless of the measurement setting.
I have to take daily BP measurements during titration for ADHD medication. (Using an _A&D UA-611 Plus_ machine at home.)
I can put the cuff on my arm and sit at my desk for 20 minutes to be nicely rested and calm, and then take 5 different measurements with a few minutes between each one. They'll vary quite wildly (anything from, say, 115/75 to 135/90) despite not moving between measurements or having any reason to be more or less agitated. I generally just ignore the low/high outliers and average the others. There's no pattern either, sometimes the outliers are first, sometimes last.
Also it's not just the monitor I have at home, the same is true of a probably more trustworthy machine in a clinical setting. I mentioned this to my doctor when I last visited and we saw the same thing with multiple measurements using a more sophisticated machine at the clinic.
mh-
I check my BP a lot for reasons, too, and this matches my experience as well. A few tips to reduce the variance (but it'll never go away):
* the position of both of your arms, and the angle your elbows are bent at matters. make sure the edge of your desk isn't pushing into your forearm.
* same goes for both of your legs. make sure you're sitting with legs uncrossed, relaxed angles, make sure the edge of your chair isn't pushing into the back of your thighs excessively.
* control your posture. slouching seems to have an effect too, but I'm unclear on the mechanism.
Anecdotally, the nurses at the doctor's offices I go to rarely (~never) bother to control for any of this other than telling me not to cross my legs. So while I fully believe white coat hypertension is a thing, I also think there's a lot of poor control of variables here. If you look up the AMA/AHA guidelines for blood pressure, the ranges they offer are predicated on some very prescriptive protocols for measurement.. which I virtually never see adhered to.
wpollock
> I can put the cuff on my arm and sit at my desk for 20 minutes to be nicely rested and calm, and then take 5 different measurements with a few minutes between each one. ...
Doesn't it take more than a few minutes for one's circulation to return to normal after a BP measurement?
devilbunny
Eh, not really. We measure blood pressure every five minutes (or less) for patients under anesthesia. They're pretty reliable. Of course, they're unconscious, so they can't really anticipate the discomfort of the cuff going up on their arm and react to that, and frankly given that they are being carved open the pain of a cuff is pretty minimal by comparison.
adastra22
Get on ACE inhibitors. Even a low dose cuts out the variance.
MikeTheGreat
Recently I was talking with someone who speculated that "hot doctors never get accurate heart rate measurements"
It took me a minute to understand (and neither of us think this is 100% true) but it's both funny and a good point.
Spooky23
My question would be… how often are you stressed?
hansvm
Yep. My heart-rate is normally pretty low (45bpm or so, 55 if I'm walking around), and my BP is on the high end of normal, but white-coat syndrome reliably brings it up to a fluttery 110bpm and 155/125 pressure. I was just in a wreck last week, so I got to see the before-and-after measurements from a few medical providers, and it's shocking how the act of talking to a new person in an unfamiliar environment spikes my BP even when I "know" that it's fine, and also how quickly it falls back down to normal.
dhosek
I got it when an eye clinic wanted to do my blood pressure (which is kind of weird in itself), which they did shortly after the glaucoma test which never works for me because I have an overdeveloped blink reflex and it turned up high.
It really amazes me how people whose job it is to take blood pressure don’t recognize the stress situations that people are in might result in abnormal readings.
dns_snek
> It really amazes me how people whose job it is to take blood pressure don’t recognize the stress situations that people are in might result in abnormal readings.
I've had a doctor measure my heart rate right after remarking on my "elevated HR during intake" (I walked there and I was running late), after telling me some slightly distressing news on what was already a very stressful day, knowing about my white coat anxiety, and right around the time of peak effects of stimulant medication which they also know about. Wouldn't you believe it, my heart rate was high (110)!
Then I got a front seat to watch their confirmation bias kick in, and have them make some really faulty assumptions based on this bad information. They were quite sure that I had developed a certain medical condition but the lab tests quickly proved them completely wrong.
stavros
110 isn't high, though?
dgacmu
I had an astoundingly high blood pressure reading last year when I tore my bicep the day after the election and dragged myself to the ER. The staff freaked. I was like, "I had a normal reading two weeks ago in my doctor's office and I'm really in an awful lot of pain and worry right now". But it still earned me the "oh shit hypertension you must do extra pre-surgical clearance".
It was kind of interesting watching my blood pressure tick down back to normal over the course of about 4 days though.
I guess the lesson is don't rip your bicep off, it will transiently elevate your BP. ;)
adastra22
If they’re doing surgery it doesn’t matter why you have hypertension, or how temporary it is. The high blood pressure causes complications for the surgery itself.
atourgates
Beyond any clinical reason that your eye clinic might want to know your blood pressure (your vascular system is pretty important to your vision) - they may have been incentivized by the CMS to track blood pressure via the MIPS program which ties provider payments to specific documentation and screening measures.
AKA - the government might pay your eye clinic more if they screen you for high blood pressure. (Among other things).
null
devinvs
my best shot at it:
year: bits 0-6 reversed
month: bits 6-10 reversed
hour: bits 13-18
minute: bits 18-24
day: bits 24-29 (maybe reversed)
y mo d h mi
25 11 10 11 3
25 11 10 11 31
25 11 10 12 1
25 11 10 12 35
25 11 10 13 0
25 11 10 13 31
25 11 10 13 31
25 11 10 14 0nullbyte808
Orange juice and bannas. My BP was 142/90 and is now 125/80. Eating these twice a day nets you nearly 2000 MG potassium.
null
broken-kebab
"I'm pretty sure that reverse-engineering this will be good for my blood pressure."
I feel healthier after reading this.
pinkmuffinere
> I tried feeding a lot of this into various Als (Kagi gives you access to a few with a nice interface) and I found that they mostly were stupid in ways that made me think
"stupid in ways that made me think" is (IMO) a really good summary of how AI is useful, as well as its pitfalls.
senectus1
yup, its a decent "Rubber duck" and an ok search engine.
0x1ch
This would imply most LLMs on the market are decent rubber ducks. Search engines unrelated. Kagi isn't changing too much (I think) besides adding additional context from search results to your requests for XYZ LLM.
vpribish
I heard it was a stuffed bear. "tell it to the bear" they'd say, and point without looking up.
Arch-TK
Would be fun to see the traffic dumps, I would love to try to figure out the protocol offline with them.
Just spent half a day reverse engineering a Windows virtual printer driver (for work) and had to force myself to stop spending the rest of the day doing it.
lifeisstillgood
So I did something similar (well less cool), but as old Software devs start finding our bodies don’t work as well after a while we will see more and more of this sort of “taking control”
zimpenfish
> "It will not connect to Apple Health"
FWIW the latest version of the app does export the previous day's averages to Apple Health (only when you open the app, mind, which can make it look like there's missing data.) I use BPExtract to read the PDF and export every reading to Apple Health but I'll definitely be giving your stuff a go as well (because automation >> manual every time.)
jamesbelchamber
That's very cool. I wonder if sniffing the Bluetooth connection directly might be easier than reading the PDF (although not because it's easy).
At least you have more than 24 hours to find out!
lifeisstillgood
I did wonder but I keep downloading to the app to “see how I am doing” Throughout the day so I would not be easily able to sniff it - and I assumed that as a highly engineered professional “medical device” it would of course be encrypted with unbreakable … oh it’s probably base64
olalonde
nRF Connect for Mobile[0] could be handy here.
https://www.nordicsemi.com/Products/Development-tools/nRF-Co...
ehnto
I am not even that old, but already seeing need to take some things into my own hands. I find going to a GP is more or less just a semaphore for specialists, and those specialists have wait times measured in months to years. I would be insane to just do nothing for that timeframe.
Although I think you need to be quite critical to have such a mindset, and assume you are wrong rather than right.
lagosfractal42
you missed a closing parenthesis
supportengineer
Not a single comment in here about Bottles - what exactly is it?
kuylar
Bottles is essentially a frontend for Wine, it lets you put every single app to its own WINEPREFIX, so that each one can have their own settings, C: drive, etc.
If you've heard of Lutris, Bottles is essentially the same thing, but aimed at general software instead of only focusing on games
nrhrjrjrjtntbt
Nice, using home-brew style incomprehensible nomenclature
Asooka
Well, things have to be named something. At least "Bottles" are related to "Wine" in a way that makes sense for a name for isolated Wine environments. It is also unique enough that Google will give you the answer quickly.
Moto7451
These have been around since I last used WINE in anger on macOS. Basically think of it as a container for running an app in WINE with all the settings predefined for best compatibility. The homepage doesn’t really highlight this but you can look through the docs for more information.
mijoharas
Have you used it/would you recommend it?
It's been a long time since I used wine (or any windows software really... Yay!) but I'm sure the requirement will pop up again sooner or later.
Should I check out bottles the next time it comes up?
ianschmitz
supportengineer
I read this entire page, it spelled out the benefits, but didn't tell me what it actually IS or DOES.
For example, "Bottles is a wrapper around WINE"
haunter
>but didn't tell me what it actually IS or DOES
It tells you right at the start:
"Easily run Windows software on Linux with Bottles!"
That's all you need to know. If Linux wants to be more mainstream it needs to drop the "Bottles is a wrapper around WINE". What's a wrapper? What's WINE? It doesn't matter. All the user need to know that you can easily run Windows software on Linux with Bottles
KeplerBoy
I guess having a look at the binary with ghidra would make this a lot easier.
khannn
"Turns out that when you check someone's blood pressure after giving them an injection, it's higher than normal."
Nick-Cage-You-Dont-Say.png
deevus
The reason Bottles/WINE doesn't work with USB devices like that is likely because WINE isn't supposed to support kernel level device access. It's for running programs and just fakes enough for that to work.
ehnto
I am only just learning this space but I believe you can set udev rules to get some USB devices working that might otherwise be failing. Worth a tinker.
I’ve been wearing a heart rate monitor for a while, and after analysing the data, I noticed something interesting: my heart rate spikes in only two situations, when I’m driving, and when I’m talking to my wife.