X-Message-Number: 3599
Subject: SCI.CRYONICS Re: Flash freeze of Humans
From:  (Edgar W. Swank)
Date: Wed, 04 Jan 95 23:22:42 PST

In Message: #3552  (Robert D Grahame) writes,

   In article <CryoNet Message: #3543> Jan Coetzee write:

   >If so, then if it was possible to flash freeze a living human and then
   >flash thaw him he should have not suffered damage from it.
    Possibly...  But the thermal conductivity of a human is extremely
    low (compared to a metal).  Even if you dunked a naked brain
    straight into a vat of liquid helium only a thin layer on the
    outside would be flash-frozen.  The rest would freeze in a normal
    manner, and the un-even contractions from that process would
    probably crack the fragile flash-frozen layer in to the bargain.

    If you could somehow pump a similar coolant *through* the brain
    quickly, then you might be on to something, but to do that you'd
    have to get the liquid out of the blood vessels first, which
    sounds like a non-starter.

Perhaps not.  I can think of two ways to evacuate liquid from the
circulatory system to be replaced by cold gas, which can be pumped
through and acheive quick (if not "flash") and uniform cooling.

First: look for a "transition" fluid, more volatile then the initial
water/glycerin based cryoprotectant, but which is miscible with it,
and non-toxic at near 0 C.  Use this fluid to "wash out" the initial
cryoprotectant.

Second: Use a partial-vacuum chamber to encourage either the
transition fluid or (at a higher temp) the initial cryoprotectant to
vaporize.  The vapor can then be washed out by circulating another
gas, like helium, or any non-toxic gas with BP less then N2.

--
 (Edgar W. Swank)
SPECTROX SYSTEMS +1.408.252.1005  Cupertino, Ca

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