X-Message-Number: 33385
From:
Date: Mon, 28 Feb 2011 02:56:51 EST
Subject: Melody Maxim's Distorted Reality 18
Content-Language: en
You write:
The only way to "assume a working knowledge of perfusion at Board
Certification level," is to hire properly educated and trained perfusionists. SA
and Alcor can certainly afford to hire qualified perfusionists, (or at least
retain a small pool, to rotate call), but I'm not sure CI can do this. If
not, they must work with what they have.
I couldn't agree more with the caveat (to which I gather you do not
subscribe) that cryonics is a discipline within medicine that requires
specialized mentoring and training. A cardiothoracic surgeon is NOT competent to
do
perfusion without extensive training in perfusion; particularly training to
develop split second judgment, rapid responses and a complete awareness of
the circuit he is operating: as if it were an extension of his body. People
who know how to drive well have a constant awareness of the position and
likely behavior of the other drivers around them; they are constantly alert
to likely (and unlikely) deviations in other drivers' behavior, as well as
in road conditions, and the behavior of their own automobile.
When I am in an OR I can immediately sense a wide range of things being
right or being amiss; I know the normal sound of a ventilator cycling
properly, of roller pumps or centrifugals operating smoothly, of the appropriate
level of tension in the voices of every person in theatre, of the sound of a
pump that has run dry or has an occluded line; the sound of bearing
starting to fail on a pump, the sound of an uncoupled impeller on a centrifugal
pump... You don't get these things in a day or a week, and if you can't get
them at all then DO NOT DO COMPLEX PROCEDURES that can deprive a patient of
cryoprotection. Nothing that CI can add to their technological base will
undo the harm of a patient who is massively air embolized and cannot be
cryoprotected as a consequence. This has happened at Alcor again and again...
Alcor had a perfusionist for a year or so to whom I carefully explained
that in patients who have had substantial cold ischemia, the aorta will be
under very slight negative pressure. This is totally counterintuitive unless
you understand the pathophysiology of ischemia. Absent ion pumping, large
amounts of vascular water move into the cells under the influence of the
Gibbs-Donan effect. Every bit of mechanically and osmotically accessible
vascular water will end up trans-located into the intracellular compartment.
Starting about 15 min post arrest the CVP actually goes slightly negative (if
you have a highly sensitive and properly zeroed pressure transducer to
measure it). When you do a median sternotomy on such patients the evidence that
the vascular volume has been depleted is that the aorta is concave. The
aortas normal configuration, if cut out of the body and placed on a table top
or in a basin of liquid, is NOT concave it is cylindrical. Why is this? The
short answer is because the aorta has elastic fibers arranged in such a
way as to make it cylindrical. The take home message is that the instant you
make your aortotomy with that #11 blade in a concave aorta air will enter
the aortic root/arch: air which you cannot see and which it is virtually
impossible to evacuate because of the physical structure of the vessel. The
first time Jerry Leaf and I saw a concave aorta we were smart enough to
realize that we needed to do something; but it took us about 10 minutes to
figure out what to do; should we cannulate a femoral vessel and pressurize the
aorta? That would take a lot of time, but would certainly work. We
ultimately decided to fill the thorax with perfusate and do the aortotomy and
cannula insertion under water. We were smart enough to identify that truly
unique
to cryonics problem and deal with it. Unfortunately, even after being
cautioned about this, the perfusionist that Alcor had on staff paid no heed
with the expected results.
What I do have is 30 years of experience doing perfusion under demanding
conditions that most perfusionists will never encounter. And I am not
speaking of cryonics cases, but rather of the years of research work with models
such as Peter Safar's dog model of CPB reperfusion after many minutes of
global normothermic ischemia. I have trained skilled perfusionists in this
model and they do not learn it easily; one described it as a combination of
his worst perfusion experiences all rolled into one; no volume, enormous
demand for flow, sky high CVP, severe acidosis, totally deranged blood gases,
no SVR and then, in seconds, massive SVR as a result of vasopressin and epi
administration; and then almost instantly a tight venous reservoir bag
which required draining into accessory reservoirs the volume of which could not
be returned to the animals for HOURS after CPB was over!
Below are photos taken during one of these experiments (circa 1998). Most
of the equipment you see was owned by me and maintained by me and I could
reliably operate all of it:
I could also manage intensive care of the animals (including vent
management and set-up and basic servicing of the vents of we used). That
expertise
extended to a wide range of ancillary equipment; IV pumps, syringe pumps,
gas blenders, anesthesia machines (everything from tearing down a vaporizer
to reworking gas regulators). The only thing I couldn't operate in the
pictures above was the computer control system; we were in the process of
automating CPB and Brian Wowk was the only one who understood that hardware and
software.
ICU care was extensive for all of our models (TBW and
ischemia-reperfusion) and we had to take a 12 hour shift alone:
Content-Type: text/html; charset="UTF-8"
[ AUTOMATICALLY SKIPPING HTML ENCODING! ]
Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=33385
Warning: This message was filtered from the daily CryoNet digest
because the poster sent too many messages per digest.
It thus may need to be rated.