Re: Slightly OT - BP measuring equipment ... ?


"Charles" <charlesschuler@xxxxxxxxxxx> wrote in message
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"Arfa Daily" <arfa.daily@xxxxxxxxxxxx> wrote in message
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Anyone on here had any experience of repairs to blood pressure measuring
equipment, to the point of understanding properly the principles involved
?

Not the kind of thing one should repair, unless its a personal project.
Even then, I think it's a bad idea.


OK, here's the story then. Not a repair as such, hence the "slightly OT" in
the subject.

The unit is actually mine. It's a fully automatic job, made by Nissei, who
are quite respected in the field, I believe. It has a wrist-sized velcro
secured air cuff, connected to the main unit by a single small bore air
hose. No electrical connections between the two. When you hit the "start"
button, the cuff inflates to a preset (selectable for four values) pressure,
which is shown on the LCD as a genuinely 'measured' - i.e. not just a figure
put there by the CPU - mmhg value. The machine then starts a controlled
deflation of the cuff, picking up pulse soon after this starts. It appears
to be assessing blood stopped / blood flowing by measuring the minute
changes in air pressure in the connecting tube, caused by the vein pulsing
under the cuff.

Now, I've recently been sucked into the 'high blood pressure' thing by my
doctor's surgery, and they are determined to treat me for it. Fair enough.
However, my 'clinical care expert' - actually a feisty practice nurse with
the disposition of a bear with a thorn in its paw - will not accept that a
blood pressure monitor that does its measuring from the wrist, has any
validity at all. I would like to be able to monitor my own pressure on a
compatible basis with her, because I feel that I am a rather good example of
elevated pressure due to white coat syndrome. This is a factor that she
seems to ignore as being a contributory element to any readings. I don't
dispute that my blood pressure is higher than ideal, I just don't think that
it is as high (on average) as she insists it is, and I don't want to be
over-medicated for the condition.

So, onto the real question. My monitor is just about identical to the one
she is using in the surgery. Same measurement sequence, same sound from the
compressor, similar sized unit, similar length of time to inflate and
deflate etc. The only difference is that mine has a plug-in wrist cuff, and
hers has a plug-in arm cuff. She actually changed to a larger sized cuff to
fit my arm when I was in there a couple of weeks ago, which is what led me
to my next thought. Arm cuffs, on their own, are available from a pharmacy
chain store down the road. They're not cheap, but nothing like as expensive
as a whole new machine. Given that it seems to work by measuring the
pressure pumped into the cuff to reach a primary inflation point to work
down from, and then apparently does the 'business' measurements by looking
at the pressure variations caused by the vein inside the cuff pulsing, can
anyone see why my monitor should not work just the same with an arm cuff
plugged in, instead of a wrist cuff ? I don't really want to just shell out
on an arm cuff in the fond hope that it *will* work, and then find out that
it doesn't, but then neither do I want to spend even more money on a
replacement unit, if I don't have to.

Any opinions / insights / genuine knowledge anyone ? :-)

Arfa


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