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Re: Pacmakers and Tesla coils = bad??




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


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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
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