NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/cryonics/715

Text File | 1992-12-22 | 5.9 KB | 116 lines

Newsgroups: sci.cryonics
Path: sparky!uunet!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!cbnewsm!cbnewsl!kqb
From: [e-mail] (kevin.q.brown)
Subject:  Identity Loss From Pre-Death Shock?
Organization: AT&T Bell Laboratories
Date: Mon, 21 Dec 1992 21:57:19 GMT
Message-ID: <[e-mail]>
X-Crossposted-To: cryonics mailing list
Lines: 105

    ------------------------ Forwarded Message ------------------------

> Date: 20 Dec 92 06:55:12 EST
> From: "Steven B. Harris" <[e-mail]>
> Message-Subject: Identity Loss From Pre-Death Shock?

Dear Cryofolks:

   I've now seen not one, but TWO dark comments this last week on
the NET to the effect that cryonicists at present are suffering
some sort of irreversible damage before "deanimation" (clinical
death).  Taking the hint from Mr. Metzger's valuable advice about
NET debate etiquette, I've decided therefore to lodge a gentle
(but formal) challenge to this spreading meme/idea, if what is
meant is what I think is meant: i.e., that the average well-
attended cryonicist dying under expected conditions is now
suffering irrevocable, or even serious, *neurological* damage
*before* clinical death is pronounced.  I personally know of no
good evidence to support this idea, and can offer at least some
indirect evidence against it.

   The indirect evidence comes from the literature of shock.
Shock is a broad term which has to do with relative lack of
tissue perfusion or nourishment, but it's also a narrower term
for a clinical state in which a patient is suffering a large
amount of such tissue deprivation.  The distinction is important,
because a patient in "shock" may not be composed of tissues which
are all undergoing the same degree of deprivation; in fact,
patients usually are not.   Among organs the heart is usually
relatively protected from shock, in part because it is literally
so close to the pump.  Relative protection for other reasons
applies also to the brain, which while most sensitive to under-
perfusion, is at the same time the tissue most jealously guarded
by the physiologic defenses of the body *against* really ir-
reversible underperfusion.   This last fact leads to one of the
interesting "paradoxes" of the clinical state of shock, which is
that while full brain function (i.e., acute mentation) is often
the "first to go" when shock sets in (showing relative brain sen-
sitivity), the brain is at the same time the last organ to be
*permanently* damaged in low-flow (as opposed to zero-flow)
states.  Shock mentation loss is reversible.   In fact, I've
never seen or read of a case in which a patient suffering
cognitive deficits solely from shock did not recover full brain
function if the cause of the shock was ultimately reversed later.
Shock mentation-deficits do not (even to any approximation)
reflect permanent damage.  Again: in shock, the kidneys may
suffer damage, the liver may suffer damage, but the brain never
suffers damage-- or at least does not suffer clinically important
damage.

   Now, of course the above is due to the body's *relative*
guarding of the brain against low-flow states (as compared with
other tissues) and so it does not apply to the state of full
cardiac arrest, in which the flow to ALL tissues is identically
zero.  In cardiac arrest (and perhaps also in some artificial
states, such as low temperature perfusion, where the body's brain
defenses aren't operative), the brain may indeed be "irre-
versibly" damaged faster than other tissues, and thus after
periods of cardiac arrest it is quite *common* to see other
organs recover, but not the brain.  But this simply means that in
"cardiac arrest" something very different is happening to the
brain (in relative terms) than in "shock."  In fact, all this is
at least one reason why we still retain the terms "cardiac
arrest" and "shock" in medicine, and do not simply lump them all
in together as states of "ischemia."   In cardiac arrest your
brain is dying while your body is relatively well-preserved, but
in shock it is your body that is dying while your brain is
relatively well preserved.  Big difference.

   Now I hope the application of all this to things cryonic is
clear.  Happy cryonicists die in a state of slow shock, with all
around them watching carefully for the time of cardiac arrest.
While in slow shock, it is certain that awful thing happen to
mentation:  patients go out of their minds, patients lose
consciousness-- at the last, a patient's pupils may even become
non-responsive.   All these things are well-known in *reversible*
brain ischemia, however, and thus the savvy cryonicist should
consider that there is no good reason to think that any of them
particularly mean anything in shock.  Simple appearances are
deceiving, as who but the cryonicist should know full well.  In
shock we know that while the heart works the brain is probably
fine, since the physiology of the average person in shock is
protecting the brain at least as well as the heart, neurologic
signs or no.

   When the heart stops, by contrast, we enter a state in which
brain damage is now proceeding apace, and we have no other tissue
damage state to use as a gauge; in fact we have now have good
reason to believe that brain is now suffering more than any
tissue.

   Knowledgeable cryonicists will thus do nearly anything to
restore perfusion and lower temperature *after* cardiac arrest;
but it is far from obvious that knowledgeable cryonicists will
worry overmuch about *hastening* cardiac arrest for a person in
pre-death shock, even in ways where it is legal.  There are far
worse dangers that await cryonicists than what happens to the
brain during monitored pre-death slow shock.  In fact, I respect-
fully submit that almost *all* the dangers that await cryonicists
are worse than this one.

   So cross it off your lists, folks.  Or at least move it way
down.

                                       Steve