My wife recently bought a fitness-tracker wristwatch thingy. The significant feature of this one is that it measures blood pressure. It is just a watch with sensors on the back. No inflatable cuff like every other blood pressure instrument I've seen.
The manual is surprisingly short. The only thing that it says about the blood pressure is that "it is more accurate than simulated measurement". So obviously some devices in this category will just measure pulse rate or something else easy and just make up a number for pressure. But this one claims to really measure blood pressure.
I've tried googling but either I get barometric pressure sensors or cuff-type devices. Does anyone here have any clues on what operating principle could be at work in the watch?
A cuff gives you two readings one for systolic and the other for diastolic pressure. Does the watch give you these two readings? I can't imagine how you can get those two reading from any sort of watch.
Grumpy_Mike:
A cuff gives you two readings one for systolic and the other for diastolic pressure. Does the watch give you these two readings? I can't imagine how you can get those two reading from any sort of watch.
There must exist a device for testing / calibrating blood pressure monitors, a search shows there are
companies that offer a blood-pressure monitor calibration service...
MarkT:
There must exist a device for testing / calibrating blood pressure monitors, a search shows there are
companies that offer a blood-pressure monitor calibration service...
I asked my then GP about that some years back, and he said yep some guy pops in every few months.
Who calibrates the calibration guy's calibrator though?
(I suppose we all know the old one about the wheel tapper who condemned a whole train before he found his hammer was cracked....)
Paul__B:
The reference is the old mercury manometer.
AFAIK reference is invasive blood pressure measurement (catheter placed in an artery). The noninvasive monitors are calibrated to mean blood pressure and are said to be quite accurate in this value (provided healthy non-obese person with regular pulse). The systolic and diastolic pressure is only guesstimate derived from the mean pressure.
Smajdalf:
The systolic and diastolic pressure is only guesstimate derived from the mean pressure.
I presume you are referring here to the wrist-worn device described in the OP.
I can assure you that on the other hand, my HEM-907 electronic oscillotonometers really do measure systolic and diastolic blood pressure.
(No connection with the company cited other than occasionally purchasing their materials. )
Paul__B:
I presume you are referring here to the wrist-worn device described in the OP.
No, I know nothing about the wrist-worn device and I consider it very suspicious it may be able to measure blood pressure. Maybe it can do some "pulse contour analysis" but I doubt it would provide any reliable result without calibration for given person and given position on hand.
Paul__B:
I can assure you that on the other hand, my HEM-907 electronic oscillotonometers really do measure systolic and diastolic blood pressure.
I know nothing about this particular device and only little about the oscillotonometry. But I was told unlike Korotkoff sounds the oscillations are measurable with cuff pressure over systolic blood pressure as well as under diastolic blood pressure. So the device have no means to determine those two pressures and only guesses them.
Well, the long and short of it is, oscillotonometry works adequately reliably to give the desired readings!
Because it is used all day, every day, in every hospital and (particularly,) operating theatre.
It is true that arterial cannulation is used for critical procedures (I do remember having a cannula removed myself on two occasions!) in order to avoid any problems with cuff positioning once the procedure is under way. And there is certainly much discussion about the relative accuracy of oscillotonometry (as there also might be with sphygmomanometry if you search and this is presumably to what your "informant" refers) but in practice, that is what we use in the vast majority of situations.
Of course, atrial fibrillation is a problem.
Not surprisingly though, wrist measurements with a cuff are not so reliable.
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