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Re: Pacmakers and Tesla coils = bad??
Some updates..
http://www.emcyork.co.uk/technical/papers/docs/emv99/emv99.htm seems to
imply that for RF EMC between 26 MHz and 1 GHZ, 3 V/m is the test field,
per IEC 801-3 (1984). Of course, this is somewhat above the range where
most TC's operate.
A warning to the reader of the above link... Figure 1, showing fields from
a GSM phone, can't be applied to a TC (there is a note that limits the
applicability to the "far field", greater than several wavelengths from the
source (.35 m in the case of the phone, many hundreds of km in the case of
a TC at 100 kHz).
Another interesting link:
http://chppm-www.apgea.army.mil/armyih/Docs/MSHP/emi.txt
Some quotes:
- Manufacturers of artificial pacemakers have long identified EMI
susceptibility problems. They subject pacemakers to susceptibility
tests to ensure that the device is adequately shielded against
electromagnetic energy levels one would expect individuals to normally
encounter.
- Susceptibility testing of medical devices is not regulated in the
United States, and manufacturers of medical devices are specifically
exempted from compliance with the Federal Communications Commission
(FCC) emission standards. Therefore. manufacturers have not been
compelled to perform susceptibility test... medical device
manufacturers may use minimal test criteria and reduce their
production costs at the expense of susceptibility. (ellipsis mine, jl)
- The majority of medical equipment now in use in hospitals throughout
the United States has not been reviewed by the FDA for susceptibility.
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Pacmakers and Tesla coils = bad??
> Date: Saturday, February 12, 2000 11:48 PM
>
> Original Poster: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au>
>
>
> This is a little long, but please indulge me !
> The note at the end could be placed in the Safety FAQ ??
>
> At 05:48 11/02/2000 -0700, Terry Fritz wrote:
>
> >It appears today's modern computerized RAM, ROM, programmable,
> >microprocessor, built in defibrillator, etc. pacemakers may be
"confused"
> >by things like arc welders, diathermy, x-ray, MRI, Shoplift detectors,
> >airport security, etc. equipment that puts out powerful RF or magnetic
> >fields.
>
> This is true, to a point.
>
> >My first thought was that Tesla coils beat all those interference
sources
> >easily!!
>
> No question !
>
> The newer pacemaker units are programmed by inductive coupling. You have
a
> PC driven programming unit which attaches to a coupling probe which is
> placed over the pacemaker (in the person who is wide awake) and the unit
is
> re-programmed accordingly while you have a chat to the patient.
>
> We usually test the defibrillators with people under light general
> anaesthesia, 'cause the jolt is a little unpleasant awake. The unit is
> capable of *inducing* VF (ie a cardiac arrest) in the patient, so that
the
> units response can be checked. In life it only goes off when the person
> has an arrest (therefore is unconscious) but to check this awake would be
a
> little nasty. A TC could easily "instruct" the unit to do this in error
!!
>
> CLEARLY, both of these devices have tuned receiving coils which are used
> for in situ programming. Both may actually CAUSE arrhythmias in the
heart
> and close proximity to a TC would be highly inadvisable.
>
> IMPORTANT NOTE: Virtually all of these devices have an in-built safety
> feature. Placing a moderately powerful magnet over the control unit
> (usually just under the clavicle, or on the side of the chest/abdomen)
will
> cause them to revert to a standard pre-programmed safety mode. This will
> however revert once the magnet is removed.
>
> For example, all operating theatres in Oz (and USA I believe) have
> appropriate magnets in the top draw of the anaesthetic machine for
exactly
> this reason.
>
> >I would think a Tesla coil would be an excellent test bed for pacemakers
> >and their susceptibility to nasty electromagnetic fields. It would have
to
> >be a lab grade device that was consistent. Perhaps a few million bucks
> >from a government grant would help out defining how a Tesla coil could
be
> >used to rate such devices... Apparently, the new pacemaker's ability to
> >deal with such emitted energy sources is a very big deal...
>
> Now I was wondering what my next research project could be ;-)
>
> Mark
>
>
> ___________________________________________________________
>
> Mark Finnis Hm: 61 8 8431 2889
> Staff Specialist Wk: 61 8 8222 4000
> Intensive Care Unit Fax: 61 8 8223 6340
> Royal Adelaide Hospital Mbl: 041 2324268
> www.health.adelaide.edu.au/icu
> ___________________________________________________________
>
>