X-Message-Number: 2815
Date: 09 Jun 94 02:54:52 EDT
From: Mike Darwin <>
Subject: SCI.CRYONICS Keith's Foley

Note that the title for this piece is Keith's *Foley*, not Keith's folly! 
I have been and continue to be terribly busy, so my postings have been
very truncated. Since I have been critical of some of Keith's posting re
the last Alcor case, I wanted to take a moment to make a positive
comment, among others.  

I already knew about the use of a Foley catheter to block the aorta (and
thus obviate the need for complex surgery to cross-clamp it) since Keith
had told me of his idea shortly after I left Alcor.  However, what I have
not done is to congratulate Keith publically on coming up with a very neat
idea.  I have not used it yet on a human, but almost certainly will.  And
yes, it is simpler actually to just do a third aortotomy and pass the
Foley retrograde down the aorta -- I have done this myself already.

In short, Keith's contribution is a valuable one -- one which will help
me and others shave time/complexity off Neuropatient surgery and allow me
to cut costs by doing the work myself or using my less skilled and less
expensive surgeon. Thank you, Keith

Keith asks for alternate explanations of the cause of the pressure drop
without accompanying volume loss.  Here are some I didn't have time to
write about before:

1) The pressure monitoring cannula tip may become blocked with a clot. 
This will cause a fairly precipitous drop in pressure (readings) -- and
it happens all the time.  It is particularly likely to happen on a case
with a long postmortem delay.  What will frequently happen is that a
clot will float in front of the catheter tip (often an ANCHORED clot) and
block it.  For this reason I run Intraflows (devices which continually
flush the pressure catheter with a few cc/hr of saline) on clotted cases. 
When we lose our waveform or our pressure on a dog (live) the FIRST
thing we do is go over to the Intraflow and squeeze it to flush the
catheter (the Intrflow will give a bolus of saline when it is squeezed).

2) The pressure transducer may have malfunctioned.

3) The TEK monitor may have malfunctioned.

4) There may have been a leak in the path from the patient to the pressure
monitor dome.  I have "lost" pressure due to someone catching a gown tie
on a stopcock handle and rotating it to the "closed" position.

I might also note that I would expect valve failure from glycerolization
to be characterized by slowly increasing flows and decreasing pressures. 
How sudden was the pressure drop and what were the relevant
flows/pressures at the time?  How far did you try cranking up the flow
(to see if pressure would come up) before you stopped?  How low did the
pressure go to and how quickly.  These are all questions, answers for
which would help a great deal.

I believe Keith said that he thought this problem was not very important. 
In this case for this patient this may be so.  But any time I see an
unexplained phenomenon which brings perfusion to a halt I WANT TO KNOW
MORE.  If it happened once, it can happen again.  Understanding WHY it
happened is the first step to preventing it next time.

Finally, one or two people have commented on the tone of my first response
to Keith (Charles Platt being one of them) characterizing it as unfriendly
or strident.  Believe me when I say this was not my intent.  There is
enough hard feelings going around without dragging technical matters into
it.  I meant my post to be simple, straightforward and free from any
hidden agendas.  I mean this one the same way.  My intent is simply to
find out what happened and to evaluate the reported events in the context
of cases already done. (If we can't learn from the past then we are in
really sorry shape.)

Mike Darwin

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