From: sbharris@ix.netcom.com (Steve Harris  sbharris@ROMAN9.netcom.com)
Newsgroups: sci.med
Subject: Re: Widespread Use Of Non-Sterile Medical Instruments In The U.S.
Date: 27 Jan 2004 17:39:43 -0800
Message-ID: <79cf0a8.0401271739.1a0a3271@posting.google.com>

willlocksley@aol.com (yelxol) wrote in message
news:<a71be19b.0401271029.3852d129@posting.google.com>...

> FATAL PROBE

> "If it (sterilization of laparoscopes, endoscopes, vaginal specula and
> probes, etc.) is neither available nor suitable, HLD (disinfection,
> not sterilization) is the acceptable alternative for final
> processing."
> "These items (laparoscopes, gastrointestinal endoscopes and vaginal
> specula) are second in importance and affect mucous membranes and
> small areas of nonintact skin ? When correctly performed,
> sterilization clearly is the safest and most effective method for the
> final processing of (these) instruments."
> Johns Hopkins University


COMMENT:

While all of this sounds rather scary, I wonder why the author isn't
out attacking a far more pervasive problem of just the same kind. To
wit, the re-use of flatware at restaurants. The knife, fork and spoon
that goes in your mouth, which is approximately equivalent to a
speculum being used gently, has been in the mouths of a lot of other
people, and who knows what kinds of diseases *they* had? Or whether or
not their gums were bleeding then, or yours are now.

And I promise you that between you and the last 100 customers who used
that spoon or fork, there was not only not an autoclave or EO
sterilization, but there wasn't even anything nearly so good as a
medical disinfection with Cidex. Rather, it probably got swiped under
a tap with a bit of greasy soap by some guy in the back of the kitchen
who is an undocumented laborer at minimum wage, and for all you know
living in the street when not washing dishes.

Old story: two ladies are having breakfast at a restarant and one
orders cow tongue. "Yuk!" says the other. "How can you eat something
that has been in cow's *mouth*?? I'll just have the eggs."

SBH

From: sbharris@ix.netcom.com (Steve Harris  sbharris@ROMAN9.netcom.com)
Newsgroups: sci.med
Subject: Re: Widespread Use Of Non-Sterile Medical Instruments In The U.S.
Date: 28 Jan 2004 12:33:05 -0800
Message-ID: <79cf0a8.0401281233.73329467@posting.google.com>

Thomas Anantharaman <tsa@biostat.wisc.edu> wrote in message
news:<NOIRb.77945>

> >While all of this sounds rather scary, I wonder why the author isn't
> >out attacking a far more pervasive problem of just the same kind. To
> >wit, the re-use of flatware at restaurants. The knife, fork and spoon
> >that goes in your mouth, which is approximately equivalent to a
> >speculum being used gently, has been in the mouths of a lot of other
> >people, and who knows what kinds of diseases *they* had? Or whether or
> >not their gums were bleeding then, or yours are now.



> I don't think the restaurant scenariou is very relavant : most people
> don't abrade their mouth with flatware.


COMMENT: I've got news for you: most doctors don't abrade vaginas with
speculums. Now, it is true that abrasion of the cervix is done
routinely with another instrument, but that one IS sterile. In the
same way it's quite common for people to abrade their gums when
brushing their teeth. Or to have gingiva which are being abraded by
poorly fitting dentures. Or to have mouth sores for many other
reasons. The spoon, like the speculum, is merely an instrument for
transfer of germ-containing fluids which are there for other reasons.


> The risk of infection of
> microbes transfered to the food from non-sterile flatware (or already in
> the food from non-sterile dishes, eg salad) is quite small since the
> primary function of the stomach acid is to disinfect all food.


ROFL! And that's why food and water-borne illness are so uncommon in
the world-- all those bugs are sterilized away by stomach acid. Not.

Look, the primary function of stomach acid may be to partly disinfect
food, but that doesn't mean it's very good at it.  Add to which the
fact that there are a huge number of people not even getting that mild
benefit, due to taking acid-suppressant medications, or being so
geriatric that their acid production is inadequate.

No, sorry, but the poster is being irrational about at least
speculums. They are generally plastic, disposible, single use, and in
any case they serve in much the same capacity as flatware.
Endoscopes, however, are a different issue, and she probably has a
point there, particularly when it comes to those used in abdominal
surgery and for surgical procedures like polyp removal. To the extent
that these things can't be completely sterilized, I'm amazed that
current guidelines allow them to be used at all, except possibly in
procedures where there is no other good choice, and there is a
significant risk of life in not using them.

SBH

From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Re: Sterilization by microwave oven
Date: Sat, 13 Apr 2002 12:24:01 -0600
Message-ID: <a99t5n$elg$1@slb6.atl.mindspring.net>

"ton4" <ways8on@lycos.com> wrote in message
news:550e20a0.0204130614.29c0ecf3@posting.google.com...
> "Chris Oates" <chrisoates99@hotmail.com> wrote in message
> news:<a98t24$ol5$2@helle.btinternet.com>...
> > "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com> wrote in message
> > [Zap.]
>
> > Microwave sterilizers are available items
> >
> > http://www.pharmnet2000.com/Avent/electric-microwave-sterilizers.htm
> >
> > very dependant on water though.
> >
> > Chris

It is indeed-- just a complicated way of boiling stuff.

And, BTW, these aren't really "sterilizers" but rather sanitizers.  The FDA
only allows the term in connection with nursing bottles and nipples because
it's an old one (and nondescriptive if you take it literally). You could not
possibly use one of these like an autoclave for a medical practice for
instuments, though I suppose it (like boiling) would be better than nothing.

Autoclaves are expensive, and they are in use still for a reason!

To kill bugs reliably at steam temp you need pressure. Even home canning and
bottling isn't reliable, and works only because you're doing it for
relatively clean fruit and vegetables, and only trying to kill a few classes
of bugs. Do a lot of meat that way without pressure, and eventually it's
going to get you.

SBH

From: "Steve Harris" <SBHarris123@ix.netcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Re: Sterilization by microwave oven
Date: Sat, 13 Apr 2002 00:44:37 -0600
Message-ID: <a98l84$g05$1@slb6.atl.mindspring.net>

"Repeating Decimal" <SalmonFly@attbi.com> wrote in message
news:B8DD23AA.83D8%SalmonFly@attbi.com...
> in article 3CB79CCC.50308@man-made.de, X-Ray at nobody@man-made.de wrote
> on 4/12/02 7:49 PM:
>
> >> A microwave won't do that. And while a pressure cooker or conventional
> >> oven can, you need laboratory procedures and controls to effect real
> >> sterilization. But if you just want to sanitize a wet dish sponge,
> >
> > Maybe I'm proofing ignorant in this matter but to my knowledge
> > all microorganisms consist of more or less polar compounds
> > (like water, solved salts, polar amino acids) which will
> > take up the mwave's energy through resonance and after a long
> > enough time they should either pop or dry out and oxidize.
> >
> > It should just be a matter of time of exposure.
>
> Maybe so. But small critters have large surface to volume ratios that go
> like 1/r. Thus, small particles (bacteria, fruit flies and the like) cool
> off faster than the get heated. The bottom line: If they don't get cooked,
> they don't get killed.
>
> Bill



Yes, you beat me to this comment. Microwave absorption is by volume, but
cooling by convection is by surface area. For a little critter you just
can't heat it up enough to hurt it, because the equilibrium temp for these
competing processes in small drops (so long as air in the oven is cool) is
not at a high enough temp.

For those who don't believe, take two cups of the sort that don't absorb
microwaves, fill one with cold water and invert the other empty and put a
thin film of water in the "bottom" (now the top). Zap them both together in
your oven until water in the full one is hot (just at the edge you can stand
to put your finger in). Now, stick you finger in the film on the other. Is
it boiling? No-- barely warm. That also happens with ants, and with a
vengeance in anything smaller.

SBH

From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Re: Sterilization by microwave oven
Date: Sat, 13 Apr 2002 12:07:47 -0600
Message-ID: <a99s79$o59$1@slb6.atl.mindspring.net>

"Richard Saam" <rdsaam@att.net> wrote in message
news:3CB8627C.4024F96B@att.net...

Several misconceptions:



> There is also a focusing effect.
> Put an apple in the microwave for about 45 seconds. The outside will be
> only warm, but the core will be very hot apple sauce .  Don't bite into
> it.


I haven't tried it, but if you get such an effect it's not due to focusing,
but convective cooling of the skin. Microwaves heat from outside-in, just
like other stuff. But they penetrate several cm, perhaps enough to get to
the core of an apple. However, they should heat the rind, if anything, even
more.




> Doesn't this whole idea of microwave heating come down to size of heated
> object relative to microwave wavelength on the order of centimeters?

No. Wavelength has nothing to do with any of this, except that the
absorption of materials from dielectric heating (which is what this is,
essentially), does depend on frequency. Lower freqencies penetrate farther.
AFAIK, the fact that in water the characteristic half-distance (50%
absorption distance) is on the same order as the wavelength (here about an
inch) is pure coincidence. It would be something else for some other
absorbtive fluid (alcohol).



> Ants and water
> films are less than a cm so they do not interact with microwave energy.  A
> cockroach may have problems.

No, they interact just as well. But they are cooled by air.

> I would guess that two well thermally insulated volumes of water of
> dimensions much greater than a centimeter placed in a microwave at the
> same time .5 V & 1 V would have the same temperature after a period of
> time


Yes, if they're insulated.


>
> If the .5 V was placed in the microwave by itself it would heat twice as
> fast as the 1 V placed in the microwave by itself.

This is true, of course, for cup-sized volumes of fluid, but has nothing to
do with what we're discussing. If you put half as much water in the
microwave, the microwave field inside your oven is effectively twice as
strong, so you DO get heating twice as fast. However, there is a limit to
this, because there's a limit to the microwave E field your magnetron can
generate without internal voltage breakdown and sparking (what happens if
you use the oven empty with no absorptive load). You can't put ants alone
and no water in there without risking damage to the oven.

I doubt you can harm ants even at the effective limit of the oven's
microwave intensity, which is set by the lowest amount of water you can put
in, with out damaging it. I don't know how much that is.

SBH

From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Ant Experiment #2: Re: Sterilization by microwave oven
Date: Mon, 15 Apr 2002 15:06:04 -0600
Message-ID: <a9ffej$5pk$1@slb6.atl.mindspring.net>

Not to be outdone in Aristotelian hair-splitting, I tried my own ant
experiment today.

Subjects: 20 vicious volunteer red ants from my local ant pile, placed in
opentop Tupperware, no other substance inside. Totally dry (they can't climb
these walls).

Sharp Carousel tabletop microwave oven on HIGH.

Ballast 5 oz water in glass, room temp (ant temp) to start.

Time to boil water by the side of the ants: 75 sec (est 600 watts).

Effect on ants: 10/20 immobilized, and appear badly injured. 1/20 running
with abdomen tucked up-- probably badly injured. 9/20 still running
normally, probably no injury.

Conclusion: Even a 600 watt microwave oven will kill ants if you leave them
in long enough. However, the ability of 50% of ants to run through a field
which has boiled a cup of water next to them (a temperature which would
surely kill all of them if they had reached it), shows that the air cooling
effect, or some other effect, drastically reduces the temperature of the
ants in these conditions, relative to aliquots of pure water with many times
their volume.

SBH

From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Re: Ant Experiment #2: Re: Sterilization by microwave oven
Date: Mon, 15 Apr 2002 15:14:49 -0600
Message-ID: <a9fg14$kth$1@nntp9.atl.mindspring.net>

Addendum:

Time to totally and undeniably kill remaining ants with NO ballast: 15
seconds.  Obviously the microwave intensities are much greater when the
experiment is done this way!

I think we can here account for nearly all of the conflicting arguments and
observations in this matter.

SBH

From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Newsgroups: sci.physics.electromag,sci.med,sci.physics,sci.chem
Subject: Re: Ant Experiment #2: Re: Sterilization by microwave oven
Date: Tue, 16 Apr 2002 12:39:58 -0600
Message-ID: <a9hr64$eng$1@slb2.atl.mindspring.net>

"Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:3CBC5875.F7625A3@hate.spam.net...
> Bruce Bowen wrote:

> > What were the dimensions of these ants?  Were they the size of small
> > "sugar ants", or larger carpenter ants, or even Uncle Al's favorite,
> > Jerusalem Crickets (ie. potato bugs, not really an ant, but proabably
> > pretty spectacular in a microvave)?  I imagine sugar ants, assuming
> > they weren't clustered, could probably tolerate a higher intensity.

Red ants-- a bit bigger than small black ants. There were in a tupperware
container which rotates on a glass table maybe 1 cm off the (recessed) metal
floor of the oven, so they may have been close enough to metal to get some
of the antinode-of-standing-wave protection effect. Will have to re-try with
both higher ants and ants given the chance to walk on the oven wall. Maybe
not today, since it snowed here last night, so the ants will be hiding
underground.

>  A Jerusalem cricket is too aesthetically awful to
> contemplate.  I bet they explode when zinged.
>
> Any god that made Jerusalem crickets and retinoblastoma is no god of
> mine.


Jeruselem crickets aka mole crickets are one of the more horrid outerspace
things you see in the ground. They are cricketoid only in the same way the
Alien in the movie Alien is humanoid. I've seen one that must have been 2
inches long poking though mud in the rocks beside the Snake River in Idaho.
I was sure the planet had been invaded by Martians. The Xanti giant ant
critters invented by the old Outer Limits to scare the crap out of people
weren't nearly as bad.

SBH