X-Message-Number: 2483
Date: Wed, 8 Dec 93 22:56:24 CST
From: 
Subject: CRYONICS Brain injury

Brook H. Norton:
 
> Is is simply the case that when resuscitation starts within 5 min of 
> clinical death, that the cryoprotectant reaches the entire brain,
> but when resuscitation starts later, cryoprotectant does not reach
> some areas of the brain, areas which then undergo a local straight
> freeze?
 
        Things aren't really that bad.  Most of the swelling 
responsible for the "no re-flow" phenomenon occurs *after* blood flow 
is restarted with the brain in a metabolically unbalanced condition.  
In fact, swelling of ischemically-shocked brains doesn't max out until 
after several hours of respirator support.
 
        Cryonics patients are administered drugs to minimize brain 
swelling right from the start of cardiopulmonary support.  Hypothermia 
is also induced as quickly as possible.  These measures help to 
maintain patency of the cerebral vasculature beyond what would 
ordinary be expected in clinical medicine.
 
        At the Institute for Biodiagnostics here in Winnipeg, Canada 
there is in fact a research group that specializes in the physiology 
of slowed metabolism.  Their research includes cardioplegia (stopping 
of the heart for open-heart surgery), hypothermic organ preservation, 
and *the beneficial effects of hypothermia on ischemically-shocked 
brains*.  In fact, earlier this year I sat through an entire seminar 
extolling the virtues and therapeutic effects of hypothermia 
administered *after* an ischemic insult to the brain.  It's this kind 
of research that gives me great confidence that cryonics patients 
experiencing 5-30 minutes of ischemia are in better shape than 
ordinary medicine would lead one to expect.
 
        My own Mother experienced 9 minutes of warm cardiac arrest 
followed by 3 hours of inefficient low-impulse CPR during slow 
external cooling in her cryonic suspension.  24 hours later, and 2000 
miles away (at Alcor) her brain perfused with glycerol excellently.
 
        This is not to say that time isn't important.  If CPR and drug 
administration is delayed beyond 30 minutes, blood clotting will 
become a problem.  As Thomas Donaldson points out, there are indeed 
many cryonics patients who suffered protracted cardiac arrest and who 
did not purfuse well (or at all) as a result.
 
                                                --- Brian Wowk

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