Pat Naughtin wrote:
>
> Dear All,
>
> Over the last few weeks, I have had a chance to see various medical offices
> and hospitals in action.
.....
> I believe that use of the unit mmHg is holding back progress in this area,
> and causing the medical profession to cling to old and dangerous technology
> because they have yet to find a way to change to the pascal, the SI unit for
> pressure, including blood pressure.
....
So, what new numbers should we get used to? Taking the commonly used
threshold of 120 mmHg for a systolic pressure that is too high, that
would come out to 160 hPa or 16.0 kPa. And a respectable diastolic value
of 60 mmHg corresponds to 80 hPa or 8.0 kPa. I don't know what diastolic
value gets the medicos concerned.
But, I can see a dangerous situation arising if a transition is made
from mmHg to hPa. The numbers are too close. A pressure reading of
150/90 is dangerous if the units are mmHg but OK if they are hPa. On the
other hand, if a patient's blood pressure were measured in hPa and
charted without units, then a dangerously low 100/60 (in hPa) would
appear "normal" in mmHg and thus be overlooked. Thus, I suggest it safer
to train people to work in kilopascals here. A charted 15/9 BP would
call attention to the fact that it is not in mmHg.
So, I suggest that we think of "normal blood pressures" as being
roughly "14/9", short for 14 kPa systolic and 9 kPa diastolic. (Charts
normally provide very little space to be explicit, hence the
"shorthand".) No need to add a tenths digit; blood pressure measurements
are neither that accurate nor that precise when taken by most common
means. In fact, I think that most doctors and nurses round those values
off to the nearest 5 or 10 mmHg.
I just checked my wife's Omron automatic sphygmomanometer. It reads out
in mmHg and there is no apparent way to change the units.
Oh, to save anyone from having to look it up,...
1 mmHg = 0.133 322 4 kPa or 15.00 mmHg = 2.000 kPa
Jim
--
Metric Methods(SM) "Don't be late to metricate!"
James R. Frysinger, LCAMS http://www.metricmethods.com/
10 Captiva Row e-mail: [EMAIL PROTECTED]
Charleston, SC 29407 phone: 843.225.6789
