←back to thread

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

(james.belchamber.com)
333 points jamesbelchamber | 4 comments | 11 Nov 25 21:25 UTC | HN request time: 0.888s | source
Show context
hermitcrab ◴[12 Nov 25 15:59 UTC] No.45901756[source]▶
I am having issues with hypertension and purchased one of these:

https://hilo.com

You put on a cuff (supplied) to calibrate it, and then you wear a little gadget on your wrist. It takes frequent measurements throughout the day and night when it senses you aren't moving. It then syncs with your phone to store the results. Its a little pricey, but seems to work well[1]. And it avoids the faff of a pressure cuff[2] and 'white coat hypertension'.

[1] Apart from the option on the app to do a reading from your finger using your phone camera - which gives wildly different results to a cuff.

[2] You need to recalibrate it every month or so using the cuff.

replies(2): >>45901857 #>>45907350 #
victor106 ◴[12 Nov 25 16:06 UTC] No.45901857[source]▶
how accurate is this?
replies(2): >>45901886 #>>45906364 #
1. barbazoo ◴[12 Nov 25 20:43 UTC] No.45906364[source]▶
> The Hilo Band uses photoplethysmography (PPG)—an optical sensor technology that collects data from your wrist. This data is sent securely through the Hilo App to Hilo’s cloud server, where advanced algorithms estimate your blood pressure using Pulse Wave Analysis (PWA), which looks beyond just the rate of your pulse, and examines the unique form of each heartbeat’s pressure through your blood vessels.

I doubt that it’s comparable to real blood pressure monitor.

replies(1): >>45907602 #
2. hermitcrab ◴[12 Nov 25 22:16 UTC] No.45907602[source]▶
I can do 3 cuff readings within 5 minutes are easily get +- 10 for each measurement. So it doesn't have to be super precise to have comparable accuracy to a cuff. Also the fact it is making continuous readings (even while asleep) is very helpful.
replies(1): >>45908035 #
3. barbazoo ◴[12 Nov 25 22:53 UTC] No.45908035[source]▶
By "cuff" you mean the brachial artery ones, right? I'd be interested in both accuracy (same value when measuring the same thing) and precision (how close to actual value).
replies(1): >>45908126 #
4. hermitcrab ◴[12 Nov 25 23:01 UTC] No.45908126{3}[source]▶
>By "cuff" you mean the brachial artery ones, right?

Yes, the one that goes on your bicep.

Anecodtally, it seems to be within the variance of the cuff (plus or minus 10).

Trying to measure both at the same time is tricky as you can't actually tell the Hilo device when to make a measurement. It does it on it's own scedule.

You are supposed to calibrate the bracelet against a cuff at least once a month.