[HN Gopher] I didn't reverse-engineer the protocol for my blood ...
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       I didn't reverse-engineer the protocol for my blood pressure
       monitor in 24 hours
        
       Author : jamesbelchamber
       Score  : 36 points
       Date   : 2025-11-11 21:25 UTC (1 hours ago)
        
 (HTM) web link (james.belchamber.com)
 (TXT) w3m dump (james.belchamber.com)
        
       | cestith wrote:
       | 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.
        
         | pavel_lishin wrote:
         | 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.)
        
           | 6LLvveMx2koXfwn wrote:
           | It's interesting that you have a baseline for 'being attacked
           | by a werewolf'.
        
         | SchemaLoad wrote:
         | If you've got one of these machines at home it seems you really
         | want to run it a couple of times. Often I find the first
         | reading I get is quite alarming but then if I sit for a bit
         | longer and run it another 1-2 times I get a very normal
         | reading.
        
           | loeg wrote:
           | Also, they can read high if the batteries are low.
        
           | llm_nerd wrote:
           | A big reason people's first measurement is often high is the
           | positioning while putting the cuff on, adjusting to the pose,
           | and then settling in place, a process which can spike
           | pressure. Ideally you prepare yourself (cuff on, in place
           | with your arms at rest, etc) and sit there and relax for five
           | minutes before you take the first measurement, making it
           | legitimately reflective of the at-rest state.
           | 
           | This is often isn't possible, but it's a reason doctor visits
           | usually drop you in a room by yourself with a machine that
           | will take multiple measurements with a lengthy delay between.
           | Though that's where the white coat thing comes into play and
           | people are stressed about a doctor coming in, etc.
        
         | lysace wrote:
         | Taking a BP in person during a medical consultation, while
         | stressed out because I know I have a very limited amount of
         | time to do a verbal data dump of a large amount of information
         | in a good way never fails to give me extreme values.
         | 
         | It also never helps to explain that this has happened many
         | times before and that I have a reasonably high quality BP
         | measurement device at home (most recently the exact same Braun
         | model) that gives me decent measurements when I'm at
         | rest/relaxed. They just look at me like I'm an idiot. How could
         | a civilian concievably master such a complex measurement?
         | 
         | Then I get the predictably insanely high measurement and they
         | look satisfied. Gotcha!
         | 
         | Please bring on the AI doctors.
        
         | alexfoo wrote:
         | 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.
         | 
         | 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.
        
       | lifeisstillgood wrote:
       | 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"
       | 
       | https://mikado-aktiia.readthedocs.io/en/latest/
        
         | jamesbelchamber wrote:
         | 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!
        
         | lagosfractal42 wrote:
         | you missed a closing parenthesis
        
       | Arainach wrote:
       | Testing blood pressure _after_ a shot seems weird.
       | 
       | I have high blood pressure, managed with a low dose of
       | medication. I've had plenty of advice from my PCP and other
       | actual doctors on how to take blood pressure - how to sit, how
       | long to sit still, how to position your arm, etc.
       | 
       | It is remarkable how many medically-adjacent professionals are
       | bad at this. My dentist starts my sessions with a blood pressure
       | reading - theoretically in case they have to numb me or
       | something, probably because it's billable or whatever. What
       | always seems to happen is that I get in for my appointment
       | (driving, which can be stressful even if I'm not running late),
       | they take me to the chair within 2 minutes max, immediately put
       | some sort of wrist cuff on me, hold my arm at an angle that is
       | not what most actual doctors have recommended to me and take a
       | reading that is often high enough to surprise both the hygenist
       | and myself.
       | 
       | The thing is that I have two sufficiently-calibrated Omron units,
       | one at home and one at the office. I take my blood pressure often
       | enough to know what it usually is (and my real doctor takes it at
       | least twice a year). That is to say that no, it's not 200/160 or
       | whatever nonsense the dentist thinks it is and you'd think that
       | with a very small amount of reading they'd know better.
        
       | Arch-TK wrote:
       | 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.
        
       | ck2 wrote:
       | I have three blood pressure cuffs
       | 
       | They all give me different numbers, by a lot sometimes
       | 
       | btw you think they ever clean those devices?
       | 
       | you think healthy people go to pharmacies?
       | 
       | I won't even touch the signature pen, imagine what's on that
        
         | kotaKat wrote:
         | If you think that's bad, just think about what's in those
         | finger-holes in bowling balls, between rounds of beer, bowling,
         | and greasy bar food :)
        
         | ErroneousBosh wrote:
         | I had my blood pressure tested several times over the course of
         | the month and each time it was high, weirdly high, like
         | 160/100. If I drove in, weirdly high. If I cycled in, weirdly
         | high. If I got another reading after sitting quietly in the
         | waiting room reading my book for half an hour, weirdly high.
         | 
         | They wanted me to start on all sorts of medications
         | immediately.
         | 
         | The second-last time, they got a reading of 220/130, and were
         | going to get an ambulance to take me into hospital immediately.
         | 
         | Er, hang on a minute, folks.
         | 
         | That's beyond "hypertension crisis" and well into "incompatible
         | with life" levels. That's the kind of pressure I see in
         | hydraulic servo feedback channels, not living things.
         | 
         | They grudgingly agreed that someone with high blood pressure
         | probably ought not to be making as much sense as I was,
         | although what would I know about it, they're the professionals,
         | etc etc.
         | 
         | The next time I noticed the automatic blood pressure cuff had a
         | fresh new calibration sticker on it.
         | 
         | 130/90. Not bad, for a reading taken at the doctor's surgery.
         | 
         | I wonder how many people are on medication they just plain
         | don't need because of a plainly faulty sphyg though?
        
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       (page generated 2025-11-11 23:00 UTC)