X-Message-Number: 33381
From:
Date: Mon, 28 Feb 2011 02:47:46 EST
Subject: Melody Maxim's Distorted Reality 16
Content-Language: en
What is being done to make low CVP drainage possible through such a
comparatively tiny tube is to use the siphon effect; negative pressure is being
generated by gravity. The experts hired by SA were idiots. They knew nothing
of even the most basic physiology, let alone the mechanics of venous
return in CPB! When I saw that picture on the cover of THE IMMORTALIST I rang
up
Saul in the US (at Alan's expense) and frantically told him of this error
and its consequences. I then sent him and Bill Falloon a follow-up email.
This wretched set-up was nevertheless subsequently used on a cryonics
patient and they could not get venous return and there was massive edema. The
mortician (wisely) decided to hook the venous return line to his water
aspirator and suck on the venous line. They were able to complete washout but
only
after causing unimaginable injury to the systemic and pulmonary
vasculature.
The people at SA were apparently never able to wrap his mind around this
concept and he complained to a competent perfusionist they subsequently
hired (a woman named Melody Maxim) about not getting adequate venous return with
fem-fem CPB and Mike Darwin's set up. What he didn't tell this consultant
was that the venous reservoir was (arguably) 15 cm above the patient's
right heart!!!!!! This may have lead the consultant to suggest centrifugal
pump assisted venous drainage which is not typically necessary and which is
very technically challenging to implement; it requires great operator skill
compared to what is available in the form of non-professionals who are
trained in-house. It is also expensive. Also, unlike in the clinical setting,
you can always put in another femoral venous cannula and return line. We have
to do this in dogs:
The proper set-up of the MALSS is shown below. These photos are from a
case where emergent CPB was undertaken in the patient's living room. CPS was
started within ~2 min of arrest and CPB was started ~140 min post arrest; I
had to cut down the contralateral
The Mobile Advanced Life Support System (MALSS) in use in a patents home
in the mid-1990s.
CLOSED-CIRCUIT PERFUSION UNDERWAY AFTER TBW:
groin because the patient had an anatomically anomalous right femoral vein
that could not be cannulated (tumor invasion). Fortunately, he had great
perfusion with the high impulse ACDC Thumper during the first 60 minutes
post-arrest and he had cooled to ~ 23-24 deg C by the time bypass initiated.
CPS supported perfusion was probably very low past this point in time; you
can see the tympanic temperature cooling rate go flat in the graph below
at about 60 min post arrest). BTW, EVERY little back box or red dot on that
graph was collected BY HAND and in real time by a fully dedicated data
acquisition person. She literally collected data as fast as she could physically
take it down. This is an important point: if we did not have that high
sampling rate (now achievable with hand held temp. Monitors like the
DualLogger) we would never have seen the flattening of the cooling curve that
probably indicates the end of CPRs utility in moving blood (this data agreed
with
our dog data).
END OF EXCERPT.
You write:
Yes, I understand Mike's done a lot of perfusion, in cryonics, but "a lot
of perfusion" in cryonics isn't equivalent to "a lot of perfusion" in
conventional medicine. He's may have done dozens of actual cases over the years,
while clinical perfusionists would do hundreds, (if not thousands), of
cases, in the same amount of time. As Mike points out, there's no substitute
for clinical experience. I pretty much cut off my exchanges with Mike, (about
perfusion equipmjent), in a relatively short time, because I felt like it
was some sort of "pissing contest," as my father would say. (Pardon me, but
that's what it felt like, and I can't think of a more accurate, but
polite, term.) I have a feeling this discussion could become much the same
thing,
in light of Mike's criticisms of CI, for consulting with me, so don't
expect this to be a "back-and-forth," on my part. This will probably be a
"one-shot rebuttal"...
If all I had was perfusion experience in cryonics Id have had essentially
no experience at all. At one time I was a Board eligible perfusionist, but
I never sat for the Boards and quite honestly, I did very comparatively
little clinical perfusion. I started out in extracorporeal medicine doing
acute (ICU) hemodialysis and working in the dog lab doing CPB. My guess would
be that I've pumped ~1,000 animals in my career; this is a trivial case load
compared to that of a profession perfusionist over the same span of years.
On the other hand, they call it a learning curve because it does plateau
and after a certain amount of experience, animal or human, you do reach a
level of knowledge and experience I liken to having learned to ride a bicycle.
Having said, make no mistake about it, it has been 8 years since I've done
CPB and I would require substantial re-education in terms of my procedural
skills and knowledge; reflexive behavior and immediately accessible
knowledge and judgment. And this brings up THE critical point I was trying to
make: there are two kinds of knowledge in a craft: didactic (book or factual
knowledge) and procedural or hands-knowledge. To some extent it is almost
impossible for most people to master didactic knowledge in a discipline like
surgery, perfusion, or operating an automobile without also having
procedural knowledge; actually DOING the tasks involved, like driving an
automobile
under real-world conditions if you want to be able to drive a car. Once you
have mastered both the didactic and procedural aspects of a craft or
profession, you can usually maintain the didactic portion of your competence,
and currency in the field, by diligent reading, interaction with colleagues,
attending seminars and conferences and observing your discipline being
practiced (preferably at centers of excellence). However, you will NOT be able
to do procedures without interning and retraining your hands and reflexes.
Indeed, it goes deeper than just hands skills because you will make
procedural errors such as clamping or unclamping the wrong line, taking too
much
time to make a decision, or even making the wrong decision given only a
short time to react.
I know about this first hand because I have experienced it several times
during prolonged lay-offs from pump work. I learned to actually budget in
several dogs as screw-up runs when the team had been away from CPB for more
than 3 months.
So, my point was (and is) that I would not have, and in fact did not do
what Ben asked me to do, because I felt very confident CI would pump air. My
recommendations to Ben were essentially the same as yours (judging from the
photo and text that appeared in Long Life): digital roller pump, medical
grade tubing that is preferably discarded or properly reprocessed,
combination oxygenator (to be run with 100% N2; He would be preferable but cost
was
an issue) and heat exchanger, auto-venting 40 micron filter, purpose-built
reservoir with fluid addition baffles to prevent air entrainment and a
perfusate addition port below the liquid level for adding perfusate, connector
with port and 4-way stopcock at the arterial cannula to allow for aspiration
of bubbles in the aortic arch or other vessels, large caliber cannula with
an Intracath pressure monitoring line or a separate arterial line, heater
cooler (easily and cost effectively fabricated in house to allow for
subzero chilling of perfusate via the HEX) I strongly recommended, and have
done
so for over 20 years (!!!!), that CI use median sternotomy and RA drainage
assisted with the appropriate venous cannula and gravity. Since they have
refused (for 20 years) my last suggestion was stenting the RA and draining
the thorax with an array of several cardiotomy suckers. And my best advice,
if they insisted on using the carotids and vertebrals for vascular access,
was to measure pressure with a set-up like this coupled to a robust and
easy to operate transducer and monitor set-up:
In fact, I've tried repeatedly to argue that they can successfully perfuse
most whole body patients who want body perfusion solely via the femoral
approach by using properly sized Biomedicus flat-wire venous cannula; I've
perfused 7.5M glycerol via this route! I even offered to let them use this
equipment at no charge to see if they could work with it effectively.
But all of this requires more than just a few days training. We had to
pump dogs on a regular basis using a survival model to maintain the necessary
procedural skills. In fact, this level of activity was necessary for people
to even be able to find the necessary supplies on the shelves. Once you
move from extreme simplicity you begin to need to lots of things and those
things require organization and familiarity; neither of which can occur absent
experience. I was thus unwilling to create an environment where there
would be some benefit at the risk of enormous harm. Primum non nocerum.
The set-up I saw CI using horrified me; and Bens unwillingness to
substitute cable ties for corroding old hose clamps both baffled and disgusted
me.
Metal hose clamps are impossible to sanitize, can easily cut gloves and
protective clothing, and can (and often do) cut through tubing. I actually
pressured Ben to take me to a home improvement store and buy cable ties and
cheap applicator tool; although he said he could see no reason to use them!
That kind of lack of understanding and behavior shouts to me that under no
circumstances should I introduce complex and not well understood elements
into CIs practice absent extensive teaching and training; if not from me,
then from someone locally, perhaps found via AMSECT. I used to teach basic
dog CPB to cardiothoracic surgeons and my experience with those (mostly)
arrogant SOBs was that they had to kill a few dogs before they would listen to
me. These were highly intelligent people with an excellent head for
medicine and extensive background knowledge in physiology and pharmacology.
When
someone argues with me endlessly over cable ties for securing the
connections on extracorporeal circuit tubing or about the advisability of using
heparin or other anticoagulants post-arrest, I KNOW they have no business
running even the arterial leg of a CPB circuit.
Beyond the experience at CI, I have had what is now onto 2 decades of
horrible experience at Alcor and SA. Some of the people at Alcor are bright and
seemingly technically knowledgeable. However, all you have to do is watch
the Discovery Channel documentary Immortality on Ice (1996) and see Alcor
patient Stanley Penska being washed out in a mortuary with a PortiBoy
embalming pump and NO VENOUS CANNULA!!!!! The venous return is geysering out of
his femoral vein; periodically Hugh Hixon or Tanya Jones reposition the
mortuary clot forceps and out comes another jet of pink fluid. Unlike me, Hugh
can do the math that underlies the Poiseuille equation and can calculate the
resistance to flow and the pressure that will develop in any length of
tubing as a function of diameter, viscosity and flow rate. So, why are such
errors made??????
I have seen this over and over and over again, ad nauseum. Alcors
replacement surgeon (for me) actually asked me why we could not use a patients
Hickman central venous catheter for the venous return line on cardiopulmonary
bypass (CPB) instead of going to all the trouble of putting a purse string in
the right atrium and placing a two-stage venous return cannula! This was a
professional who was a practicing veterinarian and who had supposedly had
extensive experience with CPB in dogs, sheep and pigs!!!???!!!!! She was
holding the Hickman catheter in her left hand while palpating the tip of it
in the SVC; this is a tube with an external diameter of perhaps 3 mm and
through which it is very hard to force 500 cc at 300 torr pressure in 10
minutes! You could have knocked me over with a feather. I couldnt make this
stuff up if I tried!
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