From: aharris@javelin.sim.es.com (Alan Harris)
Subject: coma, cardiac arrest and near death exp.
Reply-To: aharris@javelin.sim.es.com
Organization: Evans & Sutherland Computer Corp., Salt Lake City, Utah
Date: Fri, 16 Oct 1992 16:59:35 GMT

First- Thanks for the positive posts and E-mail regarding my last
post about my dad's uncle.  It seems that most people really do want
to learn from others experiences and feel it important to treat them
with respect so that these experiences aren't kept secret.

Just a few thoughts on the topic of coma and cardiac arrest.  
I spent about five years during college working as an emergency medical
technician on a small town volunteer ambulance service.  Hardly like
being a paramedic in New York or L.A. but I did have some interesting
experiences.  One thing that I learned is that during a coma, some parts
of the brain may still be very active.  It is not uncommon for a person
in coma to recognize a voice and understand what is going on around them.
Doctors can sometimes tell if a person is aware by measuring their pulse.
If the patient's pulse quickens everytime a certain person comes to visit,
then the patient may very well recognize and undrstand the voice.  People
have awakened from comas and reported that they could hear and understand
but they just couldn't respond.  The point is that during a coma, the brain
may still be active in some areas.  Coma patients could have dreams and 
halucinations that make them think they have had a near death experience.

Cardiac arrest however is a very different matter.  In cardiac arrest, blood
flow stops.  Cells in contact with the blood continue to use the oxygen
and replace it with carbon dioxide.  Since the blood is not moving, the
oxygen next to the cells gets depleted right away.  I've heard that you have
about 15 to 20 seconds of conciousness before brain cells become so oxygen
starved that they slow and stop working.  (when you hold your breath, the
blood is still moving.  Even though it isn't well oxygenated, it can keep you
concious for a minute or two.)  Anyway- During a cardiac arrest, where no
one is doing CPR, I doubt there is enough brain power to produce a dream or
a halucination.  I don't know this for sure but I believe it is true.  Like-
wise, the drowning person, underwater for a few minutes is in the same
situation.  I can believe that halucinations account for some near death
experiences in comatose people with working or partialy working brains, but
I don't think halucination explains what happens to a cardiac arrest, drowning
or otherwise oxygen depleted person.  One post suggested that since it is
common for people to be revived after several minutes underwater or in cardiac
arrest, that their brains must be alive and working. therefore they could have
had a halucinated near death experince.  I disagree.  First it is very UNcommon
to revive someone after even a few minutes of no blood flow.  Brain cells 
begin to die from 4 to 6 minutes after blood flow stops.  Children with very
healthy bodies who have drown or suffocated, have been revived after 10 or 12
minutes without oxygen, but they almost always show signs of brain damage in
those cases.  I doubt their brains were halucinating when they don't  have 
enough oxygen to even maintain life.  There are rare cases of revival after
up tp an hour under water but that is ONLY in the case of cold water drowning.
It appears that what happens is the brain must be cooled very rapidly in the
4 to 6 minutes before the cells begin to die.  This only happens in freezing
or near freezing water.  The persons brain is held in some kind of "suspended
animation" untill they are warmed and blood flow is restored.  I sincerely
doubt that in that condition that they are dreaming or halucinating either.

In summary- the old saying  "Oh you just had a halucination." may apply
in some cases, but probably not in all cases where a person has had a
near death experience.  And halucination certainly doesn't explain how
a person appears to know things that happened remotely from their body.

Alan