X-Message-Number: 28687
Date: 25 Nov 2006 23:44:07 -0000
From: "Kevin Q. Brown" <>
Subject: Re: Brain Cell Death due to Oxygen Deprivation

My reply in CryoNet message # 28685 was so focused on the details,
ischemia and reperfusion injury, that it completely neglected
the larger picture.  The prognosis for a cryonics patient should
_not_ be based on the capabilities of current medicine, but instead
on the capabilities of medicine decades or centuries from now.

That is the remarkable, central principle behind cryonics;
a person whose condition has deteriorated beyond the capabilities
of today's medicine may be cryopreserved and then one can _wait_
for technology to catch up.  Although cryopreservation does
inflict some additional injury, it is a one-time cost, and
the patient then will not get any worse for hundreds of years.

But will it ever be possible to revive a person after cryopreservation?
Although we expect medical technology to become far better within
the next few decades, it still will have limitations.  Ralph Merkle's
article "Molecular Repair of the Brain" at:
describes one hard limitation, for _any_ future medical technology,
in the section:
    The Information Theoretic Criterion of Death
Roughly, one must preserve _structure_ to prevent information theoretic
death, whereas today's medicine is limited to situations in which one
also preserves _function_.

We do not know for certain that today's cryopreservation methods
succeed in preventing information theoretic death for a human.
They certainly do not yet preserve function.  But under good conditions
current techniques actually do a good job of preserving structure.
Furthermore, recent vitrification protocols can, under ideal conditions,
preserve not only structure but also function for selected tissues and
maybe small organs.

The feasibility of revival from cryopreservation thus has not been proven,
but there is reason for optimism.  And the technology is getting better.

Meanwhile, there always are not only medical, but also logistical, legal,
economic, etc. issues to overcome just to get a good cryopreservation.
Most people do not get preserved under ideal conditions, because of such
practical, everyday problems.  There is much work to do.

Kevin Q. Brown

(Please include "cryonics" or "CryoNet" in the subject line.)

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=28687