[AMRadio] Insulin Pump RFI?


Ed Berbari eberbari at indy.rr.com
Fri Mar 4 22:35:04 EST 2005


Jim,

Your prior work sure sounds like it was fun.

About 12 years ago I got involved with some RF issues with medical devices
and it was indeed surprising to find out how little testing was done.  Some
is beacuse the vast majority of medical devices come from small companies.
For example, motorized wheel chairs back then used unshieled analog cables
to the joystick controller and there were several examples of RF
interference from passing cars with trasmitters (police cars)  causing these
devices to unlock their brakes.  In this period the FDA was barely equipped
do do this testing.

Newer devices are designed with greater awareness of these issues, but there
are still a lot of legacy devices out there.  I got particulary involved
with the cell phone/pacemaker problem back then as well. Those devices have
been significantly improved since then.  I know nothing about modern
infusion pumps, but there wer many susceptable ones in the past.

Ed,  W9EJB


----- Original Message ----- 
From: "Jim candela" <jcandela at prodigy.net>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Friday, March 04, 2005 7:42 AM
Subject: RE: [AMRadio] Insulin Pump RFI?


>
> Ed,
>
>    I used to work in a EMI lab where we would test military gear for EMC.
> That was back in the late 80's when the standard test criteria was mil-std
> 461. We would test in a RF proof chamber (metal walls) and would bombard
the
> unit under test with RF from 14 Khz to 18 Ghz at high field strength.
> Everything tested failed at some frequency and at some field strength. We
> would also test by conducting RF into the wiring. This was a ham radio
> operator paradise where an array of amplifiers, antennas, spectrum
> analyzers, etc. were used daily. My ham radio knowledge paid off too where
> sometimes we had to clean up the RF with quarter wave stubs, filters, etc.
> because the broad band amplifiers often passed on harmonics at only -20 db
> down.
>
>   I guess the point is that although medical devices implanted in our body
> can be life saving, given the right circumstances they also might do the
> opposite. I hope that the manufacturers test the heck out of this stuff
> similar to what I used to do with military gear in the old emi lab.
>
> I sure miss that job..
>
> Regards,
> Jim
>
>
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net]On Behalf Of Ed Berbari
> Sent: Thursday, March 03, 2005 4:16 PM
> To: Discussion of AM Radio
> Subject: Re: [AMRadio] Insulin Pump RFI?
>
>
> Gentleman,
>
> The interference problem between RF sources and medical devices is real,
but
> fortunately a declining one.  For many years the medical device industry
did
> not do a good job in their designs but most devices were in a controlled
> enviroment.  However the medical devices have moved to the real world with
> such devices as pacemakers, etc.
>
> A lot of the intereference has to do with the mode of modulation.  The
newer
> digital phones can actually have peak power outputs of 10-12 Watts and
> indeed could cause some problems with devices like pacemakers.  This
problem
> was identified early on and there has been a fix.
>
> However the risk can be real.   http://www.ou.edu/engineering/emc/
>
> Ed, W9EJB
>
> ----- Original Message -----
> From: "Jim candela" <jcandela at prodigy.net>
> To: "Discussion of AM Radio" <amradio at mailman.qth.net>
> Sent: Monday, February 28, 2005 7:12 AM
> Subject: RE: [AMRadio] Insulin Pump RFI?
>
>
> >
> > I asked my brother, a diabetic, about radio interference to his insulin
> > pump. He is a lawyer, and I hoped to get a legal answer to a
hypothetical
> > case where he went into insulin shock as a result of my being on the air
> > waves:
> >
> >
> > Question:
> >
> >  John,
> >
> >    A hypothetical case. Your my neighbor with a
> >  insulin pump, and I am a federally licensed ham radio
> >  operator. I am transmitting within the law on a
> >  licensed frequency, running legal power, etc. Your
> >  pump is susceptible to strong radio waves... One day I
> >  am talking on the air, and while talking, a ambulance
> >  takes you away. Seems your in insulin shock due to a
> >  pump malfunction. Where is the law on this issue?
> >
> >  Jim
> >
> >
> >
> >
> > Answer:
> >
> > Jim,
> >
> > You are a mad man.  Actually, from looking at the manual of this thing
the
> > more likely problem is from the pump interfering with other devices
using
> > radio frequencies.  The RFs on the pump are used to transmit readings
from
> a
> > glucose test meter to the pump.  The book says that interference will
not
> > affect the actual pump operation.  As to your question the manual says
> that
> > the pump must comply with Part 15 of the FCC rules and it must accept
any
> > interference received.  That aside, if I survive in your scenario, look
> out!
> >
> > John
> >
> >
> >
> > Side note: If his insulin pump was creating interference, and causing me
> > trouble receiving the Collins net this Wednesday, would it be
appropriate
> to
> > ask my brother to turn that darn thing off? :-)
> > --
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