On 5-9-2012 22:49, Orchid Win7 v1 wrote:
>>>> But the method you describe is the more easy and cheap one.
>>>> Now you are unemployed I suggest you do your research before making any
>>>> sweeping statement. ;)
>>>
>>> In particular, I know a guy who has high blood pressure. The doctor has
>>> given him this very expensive-looking piece of automated blood pressure
>>> measurement equipment. Now why would anybody design such a complicated
>>> and expensive apparatus if a simple finger clamp could do the same job
>>> with a few light sensors?
>>
>> Because it is not simple? It is for a patient more easy to screw up the
>> finger measurement than the arm cuff. You need to measure at the level
>> of the heart. Easy for a sitting/standing/lying person with the cuff on
>> the upper arm. The only way to do it wrong would be to lay down on your
>> side, not a very likely error. For the finger measurement lying down is
>> almost the only option.
>
> Hmm, interesting.

typical pressures that you measure are about 1-2 meters of water (though 
generally expressed as mmHg).

>  From what I've seen, as soon as the guy sits down to take a
> measurement, he immediately becomes so totally apprehensive that his
> blood pressure goes sky-high. I would imagine that has a way, way bigger
> impact on the readings...
>
> (But what do I know? I'm not a doctor.)

No, well known effect. That is why it in general better to let someone 
measure themselves and not someone in a white coat. If his blood 
pressure still rises after a week of use, perhaps better consult a 
psychiatrist.

>> Even if it does look expensive, it may not be and the finger measurement
>> system it not cheap and I am not even sure you can buy it as a private
>> person giving that it needs calibration and some training to use.
>
> I did say "the doctor has given him" this gizmo. You would think they
> would give him the cheapest possible device.

No I wouldn't. the cheapest device may be so unreliable that it is not 
the best price/performance. And there are many other factors, some you 
may not wish to know as a consumer in the medical market.

>  It /is/ government money,
> after all... And a brick-sized machine with sensitive specially
> calibrated pressure sensors and complex mechanical parts cannot possibly
> be cheaper than a device with no moving parts that literally consists of
> just an LED and a photoresistor.

well, perhaps you should do some research before claiming that something 
is not possible. Or claiming to know how something works.


-- 
Women are the canaries of science. When they are underrepresented
it is a strong indication that non-scientific factors play a role
and the concentration of incorruptible scientists is also too low

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