TOWARDS BETTER PERFUSIONS
Dr. Peter Gouras is a Professor of Ophthalmology at
Columbia University and is a member of CI’s Scientific Advisory Board. He
recently wrote CI’s President, Ben Best.
I am puzzled by the lack of lower extremity perfusion and
the abdominal edema produced by lower body perfusion with ethylene glycol and by
the backflow into the head. How is performed? Is it done through the descending
aorta with a clamp on the ascending aorta and an opening in the heart for
efflux?
Peter Gouras
Ben replied: The brain is perfused by cannulating the
carotids (and vertebrals) and perfusing upward. The body is perfused by
reversing the direction of cannulation of the carotids and perfusing downward.
It seems that the gastrointestinal tract is highly sensitive to ethylene glycol
and that the vessels rupture and empty perfusate into stomach and intestines.
That is my wildly uneducated guess at what is happening. I do know that we have
twice attempted to perfuse the body with 80% ethylene glycol and in both
instances (the 74th patient and the 77th patient) the perfusions were stopped
because the abdomen simply swelled because of filling with perfusate and no real
perfusion was occurring.
http://www.cryonics.org/reports/CI77.htmlIt
was only for the 77th patient that I measured core brain temperature. The head
was in a slurry of dry ice and n-propyl alcohol so there should have been
considerable cooling of the head from the slurry. Yet during the body perfusion
the core brain temperature rose 2ºC. This probably means that backflow from the
pressure of the body perfusion was entering the head of the patient through
collateral vessels -- thereby compromising head vitrification.
Andy believed that it was only special circumstances with
the 74th and 77th patients that caused these problems. The 74th patient was a
cancer victim and in his experience cancer patients typically perfuse poorly.
The 77th was a 96 year old man, but I see no reason why he should have not been
a good candidate for perfusion, especially in light of the fact that he had been
heparinized. He was well-iced quickly and there had been 24 hours between
deanimation and perfusion. There was deterioration during his final days before
he was finished by a stroke, but his condition was not worse -- and probably
better -- than the typical CI patient.
I was prepared to attempt a body perfusion for our 81st
patient and I was prepared to apply a tourniquet to the neck to attempt to
prevent backflow. But the patient was too edematous in the abdomen already for
us to consider body perfusion. I discussed the idea of body perfusion again with
Yuri today and he seems to think that the collateral vessels would be too deep
and that the tourniquet would not work. Yuri is concerned about both backflow
and the body edema and he would like to do experiments in Ukraine before we
attempt another body perfusion. I am torn between my desire to please our
Members who want body perfusion and my concern about the ethical problem of
experimenting when there is past evidence of failure and grounds for suspecting
that my tourniquet might not work.
By the way no one has picked up on my note on perfusing
rather than thumping. Why not?
Possibly partially because you submitted it as a WORD
document and partially because we have been frantically busy with lots of things
since you sent your message. I have extracted your text from the WORD document
and reproduce it in pure ASCII text below.In many respects your suggestions are
a "non-starter" which we cannot even consider because they are based on a
misunderstanding of Cryonics Institute procedures. CI cryopreservation
procedures are summarized on the following page (which is mostly extracted from
numerous case reports):
http://www.cryonics.org/phases.html
We have not done a local standby case in many, many years
and I only know of one instance in which CI used a thumper. Suspended Animation
does use such procedures. For remote cases we have decided that we will not ask
funeral directors to touch a carotid because the danger of damage is too great.
We asked a funeral director to administer heparin into a jugular with our 79th
patient and he damaged the vessel on the left side before successfully injecting
into the right side. So we won't be asking funeral directors to inject in
jugulars either. Your suggestions might make more sense if we had people with
the right expertise to carry them out. Also, we cannot do brain perfusions in
the back of a van. Under Michigan law we are a cemetery and the perfusions must
be done at a funeral director's facility.
Ben Best
Ben I have read over the cryo-preservation protocols.
I would like to make the following suggestions, which I would like you to read
and tell me whether these ideas make any good sense to you and whether it should
be promulgated in long life for further feedback and discussion. I attach it.
Peter Gouras
SUGGESTIONS FROM DR. GOURAS
Modifying the Cryo-preservation Procedure by Peter
Gouras, M.D. June 1, 2007
At present we cool the head and thump on the chest after
administering solutions including heparin. Oxygen is cycled into the lungs by a
face-mask. This thumping may continue in transport to Detroit but in most cases
this thumping will cease during air transport when we must tolerate a cool but
un-perfused head and brain.
I presume that injections of any solutions are ideally
administered before death. Administering heparin into a vein after death may not
circulate well with a thumper mediated flow. I am troubled by how well the
thumper is circulating blood through the brain and head and I don't see any
feedback that monitors the effectiveness of the thumping. I consider such
feedback important. Not knowing how well blood is circulating is a great
handicap.
I would like to suggest another strategy. I recommend
that the first thing to do after death is to cannulate the carotid artery and an
adjacent (jugular) vein; both jugulars would be even better. This would allow
perfusion of a cool balanced salt solution to the head and brain; this solution
should be saturated with oxygen (about 0.3 cc oxygen/cc solution) without
erythrocytes and some albumin should be added for oncotic pressure. This would
allow assessing the return flow by watching the color of the solution leaving
the jugulars; this provides some monitoring of successful flow. Ideally the red
blood cells should clear in the return flow. One could conceive of a small light
emitting diode stimulating the eye that would allow detecting the retinal and/or
the brain's response to this light stimulus. This is even better feedback on
effective flow. Temperature would of course influence these light evoked
responses.
I suggest this strategy because of a method I published
years ago (Investigative Ophthalmology 9 (5): 388-399, 1970) and which was
continued by a fellow in my lab, Gunter Niemeyer (Ibid 33 (10): 2798-2808, 1992)
of perfusing the mammalian eye through its major artery using the technique
described above. This maintains the function of the neural retina for days and
this function is readily monitored by the neural retina's response to light.
Electron microscopy reveals excellent preservation of the neural retina as well
as the entire eye using this method. The flow rates through the small ophthalmic
artery were about 0.2-0.4 cc/minute. This would have to be much greater to
support the head but do-able through the carotid.
Now this would allow the brain to survive (and in fact
function if the temperature were raised) for certainly a day and probably longer
(without any heart beat). Then I suggest that we invest in a van that would
allow the subject to be transported to Detroit while brain perfusion continues
in the back of the van. A day or even longer should be sufficient to reach
Detroit from most parts of the USA.
I suspect that the brain would be in relatively good
shape during this entire time if the circulation were adequate. On arrival the
rest of the perfusion and cryo-protection could be carried out on a brain that
might still be able to function.
I propose this strategy and I would like to
know how it goes over with the readers of Long
Life.