X-Message-Number: 33377
From: 
Date: Mon, 28 Feb 2011 02:00:35 EST
Subject: Melody Maxim's Distorted Reality 12

Mike Darwin: ***Since I am opposed to using hard-shell open  reservoirs I 
wont comment here beyond saying that Boons interpretation is  correct.***  
4. Melody Maxim: Deleted excess connectors from AV loop.   
Its best to have only the two cannulae connectors most likely to be  used 
inserted in the AV loop, with others available.   
Mathew Sullivan: As mentioned during the meeting, I recommend that  we 
universalize our cannulae connections by inserting any appropriate fittings  

deemed necessary to our cannulae and re-sterilize them. This ensures no matter
if we are working on a full sized adult or a small child that we can 
connect the  cannulae to the tubing without having to make any last minute 

adjustments. The  most obvious example of this might be to insert a   x   
connector 
into a venous  cannulae, then re-sterilize it. This may seem strange to 
perfusionists out in  the real world considering they would use a small tubing 
circuit with the  interest in a small circuit volume for a child, but our 
tubing packs are one  size fits all and this is okay in our situation because 
we do not have the same  concerns associated circuit volume and the need for 
blood.   
We should also consider or debate the possible use of quick  disconnects 
made by Qosina that Medtronic was using at Mechanisms.   
Mathew Sullivan: Question is what are the percentages that you will  be 
working on a small child, my guess is probably not often. The quick  

disconnects that Medtronics Resting Heart System circuits are using may be a  
good 
solution.  
Mike Darwin: ***Unfortunately, I dont have the text at hand, but  Alcor 
recently (last 12 months or so) pumped a patient full of air in the field  

because they did not have the right sized connector and the mortician tried to
jury-rig something which, as best I can tell, created a venturi at the  

connection between the arterial line and the arterial cannula thus allowing for
sustained and undetected (until foam came out the venous line) air 
embolization.  In several cases perfusion was either not possible, or mortuary 

cannula and/or  equipment had to be used because there was a missing connector.
One of these  cases was the mother of a world-renowned biomedical researcher. 
I have been  criticized for calling people who do this kind of things 

IDIOTS, but I honestly  dont know what else to say. The first time it happens is
inexcusable, but to  have it go on, and on, over 15 years is sheer idiocy. 
Nevertheless, this is the  way it is. An inexperienced person digging through 
lots of supplies on a tray or  in a kit-box may be unable to find or 

recognize the right sized coinnector. I  know that seems impossible to you (and
me) but it has happened. I used to keep  every conceivable sized connector in 
my goat so that when I filled the goat with  saline I would empty out my 
pile of connectors onto the cutdown or major  thoracic tray thus they were 

always at hand and in the sterile field. And, of  course, I could tell a   x 3/8
connector from a 3/8 x 3/8 connector on sight.  You only get that ability 
by handling these things on a near daily basis.   
While you may well know in advance that you are doing a child, and  the 

odds may be low, you cant count on that. No child has been cryopreserved  since
the early mid to late 1970s. However, there are children signed up and  

there may well be a pediatric at-need case. You need to at least be able to go
from 3/8 to  .  
What is more, I kept a selection of stainless steel cannula on my  tray 

(maximum size 6 mm OD) which I could use on very atherosclerotic patients.  The
femorals of some elderly patients will only accommodate a small cannula and 
 these all have   tubing barbs. You can easily deliver 5 LPM a minute 

through  such a cannula (I did it all the time on dogs) albeit at the price of a
high  back-pressure between the pump and the cannula.***  
Melody Maxim: The venous cannula currently being used has an  incorporated 
3/8 connector.  
Mathew Sullivan: I dont know that we have come to any firm  conclusion on 
which cannulae we will be using, but if or when this becomes the  standard, 
the tubing should not go past the first barb to make for easy removal  of the 
tubing. Speaking thereof, the AV loop on the training pack has both of  its 
cannulae connections past both barbs and if this were done on a real tubing 
 pack, expect the surgeon to complain a lot. Tubing or connectors meant to 
be  removed to make way for cannulae connections should not go past the 
first barb  to make for easy removal.  
Melody Maxim: The arterial cannula does require a 3/8 connector, so  one 
with a luer lock has been included.  
Melody Maxim: Discuss whether this luer lock is acceptable to  replace the 
previous manometer port connector.  
Mathew Sullivan: My assumption here is that we will be going with  the 
arterial cannulae with pressure manometers built within unless someone can  
think of a reason not to; therefore, the 3/8 LL connector will need a one-way  
stopcock to allow for the removal of large amounts of air, sampling for those 
 who will insist on taking a sample there, or even for those who might want 
to  use a florescent die to look at patient circulation as an example as 
has  happened in the past. We used to have this type of connection next to the 
 cannulae at Alcor, but the surgeons complained enough that we moved it 
back a  few inches to allow for better handling and making the cannulae 
connection.  
Boon: I think the purpose of having a luer lock on the 3/8  connector for 
the arterial cannula is to allow air (if any) to purge out when  connecting 
to the arterial line from the pump. I do not agree with putting a  one-way or 
a 3-way stopcock there to allow for taking an arterial blood sample  or for 
measuring the arterial line pressures. You dont want to mess around with  
the arterial cannula once it is in place. Instead put a 3-way stopcock on top 
of  your arterial line filter to have access for blood sampling and 
checking your  arterial line pressures is a better way to go.  
Mike Darwin: ***This has been an endless source of frustration for  me. No 
one has listened to me over this issue for the last 15 years so I hardly  
expect them to start now. (Forgive my cynicism.)  
Pressure cannot accurately be measured in back of the arterial  cannula at 
all but the lowest flows with the largest diameter cannulae. In order  to 
measure pressure via the arterial cannula it is necessary to pass an  
intracath beyond the tip of the cannula and then hook this up to a pressure  
transducer. Yes, it can be a manometer, but this is pretty pathetic and very  
dangerous. Solid-state disposable pressure transducers and portable, compact,  
battery powered (NiMH no less!) monitors are now available. USE THEM! Use them 
 not only to monitor MAP but to monitor CVP or even venous line pressure at 
the  venous cannula, if nothing else is available.  
What you are measuring when you measure pressure behind the  arterial 

cannula is the back pressure generated by the constriction of flow  represented
by the arterial cannula. The long fluid filled line leading to the  manometer 
is just air embolism machine waiting to spring into action.  
The idea of the 3/8th connector near or on the arterial cannula  being used 
to work air out of the system before going on bypass is not  understandable 
to any professional cryonicists now engaged in perfusing people  (that I 
know of). They assume that if you dribble fluid out of the arterial  cannula 
when you insert it into the arteriotomy that you MUST therefore have no  air. 
It is impossible to convence them that AFTER the arterial cannula is placed 
 and secured that you must draw back blood and work out any bubbles. If 
they dont  see any air in the line when the insert the dripping cannula into 
the artery,  they dont believe there can be any. The fact that air may have 
entered the  artery via the arteriotomy and be present between the arteriotomy 
and the  proximal arterial ligature appears to be an impossible concept for 
them to wrap  their minds around. Of course, in the real world, if you fail 
to do this you  will pump air and you will usually have a detectable 
neurological deficit to  contend with.  
Similarly, if you simply do the rote exercise of aspirating the  vessel 

after the proximal tie is released you will almost always SEE air.  However, if
you always refuse to do this you will never see the air and  therefore you 
will never remove it. And, since your patient never wakes up, you  never see 
any harm in this Indeed, after you have completely filled a patient up  

with air and blown him up like a balloon you can confidently state: Despite the
 problems during surgery, the cryoprotection went fairly well.  
So, yes, you need a 3/8 connector with 4-way stopcock at the  arterial 
cannula to remove air prior to going on bypass.***  
5. Melody Maxim: Removed a 3/8-1/4 reducer, as well as a tube  inside a 

tube connection, from the AV loop recirc line and changed the tubing  from 1/4"
to 3/8. 


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