RF biohazard -electrosurgery units
From: Bill the arcstarter [SMTP:arcstarter-at-hotmail-dot-com]
Sent: Monday, May 11, 1998 8:18 AM
Subject: RF biohazard -electrosurgery units
It was written:
> From: R M Craven <craven-at-globalnet.co.uk>
> I suppose one way that this could be investigated would be to get a
> joint of pork, uncooked, and then ensure a path to ground occurs via
> the meat. The temperature at some subcutaneous point could be measured
> (alcohol rather than Hg in glass thermometer). Assuming the pork is
> fatty, the inside would be thermally insulated so a protracted
> run-time would hopefully generate a measurable rise in temperature.
Yep - we used to do exactly that. My employer used to mfg
electrosurgery units (called "Bovies") - which basically produce either
a damped or continuous RF current < 1MHz. This current is applied to
the patient using (usually) a narrow wire. The field at the wire cuts
and coagulates the tissue.
I don't have any data on power or current, although I'm told the output
was around 7KV or so.
We used steaks as test fixtures.
The continuous vs damped wave have different effects on tissue. The CW
was used to actively cut the flesh, while the damped would more or less
just coagulate w/o much cutting action.
Sounds like a tesla coil would produce the coagulating waveform-so at
least you won't bleed to death if an arc tags you!. :)
The electrosurgery operator could control the mix of the damped and CW
energies according the the particular surgical technique being used,
The old units contained both spark gap and vacuum tube generators for
the production of the appropriate waveform. The spark gaps were
self-gapping - each time the unit was turned on the gaps would
automatically position themselves however many thousandths apart -
compensating for wear. They used about 6 tungsten to tungsten contacts
for the gap.
One concern is the grounding of the patient. If a large metal plate in
good contact with the patient isn't used, then you'd get RF burns at the
exit point of the current! Lawyers LOVE this equipment...
Unfortunately this product line was sold about 12 years ago so I can't
tell you more than this! Many hospitals still operate this sort of
-Bill the arcstarter
Starting arcs in Cinci, OH
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