X-Message-Number: 3197
Subject: SCI.CRYONICS: High Pressure Cryonics Jelly
From: ben.best@canrem.com (Ben Best)
Date: Sat, 1 Oct 1994 22:44:00 -0400


   Bob Smart's reaction to the idea of applying 20,000 atmosphere's of
pressure to a brain in less than one second is that the brain would be
turned to "jelly".  I'm as aware as anyone that putting a brain under a
pile driver is likely to smash it to smithereens. But the issues of
high pressure cryonics are more subtle than that.

   Pressure of 1 atmosphere is equivalent to 14.7 pounds per square
inch.  If you total-up the number of square inches of skin for a typical
person, that amounts to tens of thousands of pounds of pressure. Why
aren't we all crushed? Because the pressure is exerted in all directions
and is therefore "self-equalizing".

   In the ocean, pressure increases with depth at a rate of
approximately 1 atmosphere per 33 feet. Sperm whales regularly swim to
depths of 3,700 feet (about 110 atmospheres) and there are fish living
at depths 10 times as great (the bottom of the Mariana trench in the
Pacific) at about 1,100 atmospheres pressure. The greatest danger to
animals or fish occurs with change of depth -- especially the formation
of gas bubbles due to rapidly decreasing pressure. The most serious
danger of high pressure is probably the collapsing of the lungs
(pressure on a GAS-PHASE SPACE).

    Application of 20,000 atmospheres to a cubic foot of water would do
no harm, but could turn it into a solid state -- greatly reducing
molecular mobility. If the cubic foot of water contained a brain, the
equalization of pressure in all directions could mean that the brain is
simply turned into a solid state, without being "crushed". This assumes
that all parts of the brain are equally compressible with water, which
is probably a dubious assumption -- despite the fact that the brain is
mostly water and fat.  Nonetheless, I think potential damages due to
rapid application of pressure cannot be as great as those due to
freezing damage.

    I like the simplicity of suddenly putting the brain in a solid
state, but the fact that heat of fusion might drive the temperature
to 60 Celcius (about 140 Fahrenheit) does disturb me. Such a high
temperature could easily result in undesired chemical reactions, even
if molecular mobility is greatly reduced. I think the same would be
true of room temperature storage at high pressure. I think any high
pressure techniques should be combined with low temperature technique.

    Hergenhahn also suggested a multi-stage approach. This would
involve, say, lowering the brain/water cube to minus 20 Celcius at
2,000 atmospheres and then increasing pressure in one-thousandth of a
second (I don't know where he got this figure) to 6,000 atmospheres.
This might increase viscosity and increase temperature -- but still
to a sub-zero temperature. The sample could then be cooled again and
the process repeated until a solid vitrified state is achieved.
Unfortunately, I am not convinced that this iterative process would not
result in ice crystal formation -- I rather think it would. But I might
be wrong.

    Greg Fahy has only used high pressure under very limited conditions.
I favored testing the application of pressure at various temperatures
and speeds, but his research has not led him in the direction of this
kind of experimentation. I find it frustrating that only a very few
cryobiologists have any interest in doing the kind of experiments that
are of interest to cryonicists.

                     -- Ben Best (ben.best%canrem@uunet.ca)

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