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I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

james.belchamber.com

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Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#122

Post by hermitcrab »

digi59404 wrote: post #63
mh- wrote: post #57

Earlier quoted context omitted.

Agree with all of the rest of your points, but a legitimate 220/130 is something that a typical doctor's office does observe* on occasion, so that (by itself) wouldn't have made them think their instrument was faulty. Some of those people would even be outwardly asymptomatic, as strange as that seems. * those people would be considered to be in a hypertensive crisis, and sending you for emergency care would be the ri…

Can confirm; had a 210/110 legit BP reading. Multiple cuffs and sensors confirmed. I felt it too. Walked into the ER because my Dr forced me too. After walking into and chilling for a bit. 130/70. $3000 later no answers. So, it does happen to people.

My BP pressure has slowly creeped up over the years to 155/95 range, despite being quite fit with no real lifestyle issues. Was told to monitor it. Did a reading a few weeks ago: 190 over something. Not good. Went to A&E where they confirmed the reading with their cuff. Sat there for several hours. BP kept climbing until it reached something like 235 over something (probably partly due from a feedback effect of knowing my BP was high). Felt fine, apart from the anxiety related to the BP reading. Did a few tests, but no-one seems to know why it spiked. They gave me some meds and it slowly dropped. They let me go when it dropped below 180. Now taking a calcium channel blocker and it is very slowly trending down. Now about 160 over 100.

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#123

Post by nathan_douglas »

hermitcrab wrote: post #115
rhyperior wrote: post #110

Earlier quoted context omitted.

A PA explained to me once: they’re taught you have to sneak quietly into a room where the patient has been sitting in the dark listening to soothing music for 15 minutes and take their BP measurement without them noticing. Goals.

Hard not to notice the squeeze from a pressure cuff.

Numb the arm by having the patient sit calmly with their left arm in an ice bath.

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#124

Post by jcc11 »

Played around with the format a bit and made a Kaitai format if anybody else wants to play with it. Not confident about the year, but I have observed some timestamps based on date of manufacture if the device came out approximately 2016. The rest seems to line up rather well as bit-packed integers.

Kaitai Structured Output:

  0 [BpMsg]: 2025-11-10 11:03 - SYS:137, DIA:113, OPP:121, MAP:121, PP:24, HR:67
      unk1 = 0xA = 10
      sys = 0x89 = 137
      dia = 0x71 = 113
      hr = 0x43 = 67
      timestamp [Datetime]: 2025-11-10 11:03
          yearMinus2016 = 0x9 = 9
          month = 0xB = 11
          day = 0xA = 10
          hour = 0xB = 11
          min = 0x3 = 3
          paddedDay = 10
          paddedHour = 11
          paddedMin = 03
          paddedMonth = 11
          year = 2025
      unk2 = 0x50 = 80
      opp = 0x79 = 121
      unk3 = 0x0 = 0
      unk4 = 0x0 = 0
      unk5 = 0x0 = 0
      unk6 = 0x0 = 0
      unk7 = 0x0 = 0
      unk8 = 0x0 = 0
      map = 0x79 = 121
      pp = 0x18 = 24
  1 [BpMsg]: 2025-11-10 11:31 - SYS:132, DIA:86, OPP:95, MAP:101, PP:46, HR:68
  2 [BpMsg]: 2025-11-10 12:01 - SYS:126, DIA:84, OPP:90, MAP:98, PP:42, HR:82
  3 [BpMsg]: 2025-11-10 12:35 - SYS:128, DIA:80, OPP:86, MAP:96, PP:48, HR:61
KSY:

  meta:
    id: bp
    title: BP Msg Format
    endian: le
  seq:
    - id: msgs
      type: bp_msg
      repeat: eos
  types:
    datetime:
      -webide-representation: '{year:dec}-{padded_month}-{padded_day} {padded_hour}:{padded_min}'
      seq:
        - id: year_minus_2016
          type: b4
        - id: month
          type: b4
        - id: day
          type: b5
        - id: hour
          type: b5
        - id: min
          type: b6
      instances:
        padded_day:
          value: '(day
Using the following hex dump as my source "binary":

  0a89 7143 9b52 c350 7900 0000 0000 0000  ..qC.R.Py.......
  8456 449b 52df 505f 0000 0000 0000 007e  .VD.R.P_.......~
  5452 9b53 0150 5a00 0000 0000 000a 8050  TR.S.PZ........P
  3d9b 5323 5056 0000 0000 0000 0094 5d41  =.S#PV........]A
  9b53 4050 6700 0000 0000 0000 795c 4a9b  .S@Pg.......y\J.
  535e 506a 0000 0000 0000 007b 5341 9b53  S^Pj.......{SA.S
  5f50 5a00 0000 0000 0000 7b4f 4e9b 5381  _PZ.......{ON.S.
  5058 0000 0000 0000                      PX......

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#125

Post by hermitcrab »

nathan_douglas wrote: post #123
hermitcrab wrote: post #115

Earlier quoted context omitted.

Hard not to notice the squeeze from a pressure cuff.

Numb the arm by having the patient sit calmly with their left arm in an ice bath.

Sitting for minutes in extreme discomfort definitely won't change your BP! ;0)

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#126

Post by adirelle »

rhyperior wrote: post #110
hirvi74 wrote: post #109

Earlier quoted context omitted.

Mine constantly asks me questions during my measurements. I thought one wasn't supposed to be talking during the readings either?

A PA explained to me once: they’re taught you have to sneak quietly into a room where the patient has been sitting in the dark listening to soothing music for 15 minutes and take their BP measurement without them noticing. Goals.

You are kidding but having hypertension issues for years, I can confirm you that tension is a highly-dynamic value that can change in few minutes for a lot of reasons. Here the standard toi

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#127

Post by chihuahua »

taneq wrote: post #70
pavel_lishin wrote: post #3

Earlier quoted context omitted.

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.)

Just to be clear, 'fang doctor' doesn't actually refer to a medical werewolf. :D

Can confirm, I was a FAANG doctor (Ph.D.) for a while, not a werewolf.

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#128

Post by 3D30497420 »

ErroneousBosh wrote: post #89
3D30497420 wrote: post #83

Earlier quoted context omitted.

I love those visits. I've occasionally had sharp chest pains which go away after a number of seconds. They've never been accompanied by typical heart attack symptoms, so I usually ignore it (not smart, I get it). After one such episode, I decided to schedule an appointment with my general practitioner. They refused to see me if I didn't go to the ER first. I was pretty certain I didn't need an ER visit, but went anyw…

> (For what its worth, I probably have this: https://en.wikipedia.org/wiki/Precordial_catch_syndrome ) Huh, that's interesting. That matches something that I get sometimes, usually after I've been driving a long distance or sitting at my desk doing mouse-heavy stuff for a long time. I put it down to poor posture. It hasn't happened quite so much since adjusting the steering to track and centre properly so I'm not con…

Better posture has definitely helped me as well. I most often have the pain when hunched over.

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#129

Post by bluesign »

devinvs wrote: post #47

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) unsatisfyingly I don't have any idea what the gaps are or why parts need to be reversed, so i could be wrong. With the data from the post: 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 0

I think this is the format, some parts are split ( maybe some obfuscation attempt )

0-4 month 4-7 year 8-10 hour 11-15 day 22-23 hour 24-29 flags 30-31 year

Re: I didn't reverse-engineer the protocol for my blood pressure monitor in 24 hours

#130

Post by cestith »

atourgates wrote: post #51
dhosek wrote: post #31

Earlier quoted context omitted.

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.

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 oth…

I’d like to think it has to do more with hypertensive retinopathy, but...
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