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Category: Perfusion
Forum Name: Pediatric Perfusion
Forum Discription: This forum is for discussion of cadriovascular perfusion issues in pediatric patients.
Printed Date: Sep 19 2018 at 1:09pm

Topic: M.U.F.
Posted By: coleb
Subject: M.U.F.
Date Posted: Jun 14 2009 at 9:18am
At our center we do A-A MUF.  We have had good success with it.  Can anyone tell me pros and cons of doing A-V instead of A-A?

Posted By: Prasannasimha
Date Posted: Jun 19 2009 at 9:53pm
What are you exactly referring to as AA MUF. Classicaly MUF implies withdrawing from the aorta and returning to the venous side. This allows lowering of afterload and preload augmentation, improves hemodynamics and essentially filters the patient and not the reservoir. It also returns warm blood back to the RA/PA promoting reflex pulmonary vasodilatation and decreases PVR.
You will see a regular increase in hemodynamics due to both hemoconcentration and removal of various inflammatroy metabolites ofCPB.

Posted By: coleb
Date Posted: Jun 20 2009 at 11:09am
Our surgeon once had a bad experience with A-V mufing.  The story I heard is that the right side became over loaded and the patient had to be put on ECMO.  When we finally talked the surgeon in to doing muf again, we agreed that mufing A-A or arterial back to arterial would be acceptable.  Basicly, we draw back down the arterial line and push back into the aorta through the cardioplegia system.  We have had good results.  Removing anywhere from 500 to 700 cc over 10 to 12 minutes.  The surgeon has mentioned that he does not like having to repair the Aorta where the CP line was placed, so I have hinted that it might be better to put it into the RA.  This brings up this whole can of worms about overloading the right side.  I was just wondering if anyone out there would know if there is really that much of a difference between the two MUF sites and if so what are they?

Posted By: Prasannasimha
Date Posted: Jun 21 2009 at 5:14am
The real advantage of Arteriovenous MUF is the decrease in PVR that follows.
Dr Prasanna Simha M

Posted By: coleb
Date Posted: Jun 22 2009 at 8:20am
This may be a stupid question, but just trying to understand the physiology behind it all so I can inform the surgeon with proper information.  Wouldnt A-A also decrease PVR?  If you take the fluid off the arterial side, wouldnt this in return have a positive effect on the venous, and help the pulmonary system resistance?   I am trying to talk the surgeon into trying A-V again and would like to have a solid base to present to him. 

Posted By: gmyers
Date Posted: Jun 22 2009 at 9:34pm
For the past 15 years we have been doing Simple Modified Ultrafiltration post bypass. This is where we take from the venous line and put the blood back into the arterial line (call it V-A MUF if you prefer).
There are several advantages to SMUF over the usual A-V, A-A or V-V MUF. By removing blood post bypass from the venous line we can continuously monitor the hgb/hct through the venous sat probe as we ultrafiltrate. Instead of looking at time and volume, this allows us to achieve any given target hct or have the ability to see how effective the SMUF is working.
By infusing this ultrafiltrated blood just prior to the oxygenator inlet and back into the aorta, we do not need to remove potassium from the cardioplegia device because we do not use it.  We do not have to worry about introducing emboli of any type because we run the blood through the concentrator, membrane and arterial filter before it reaches the patient.
But two of the best advantages of the SMUF system are we never have to get the surgeon to do any manipulation of cannula's or sites, because we simply start SMUF immediately after clamping the venous line.  All the surgeon does is talk about the case with his assistant until we are done.  The second clear advantage over the other systems is that we do not remove blood from the aorta, and therefore never have to be concerned about flows or stealing from cerebral blood flow during the procedure.
If you are using cerebral oximetry, look at your numbers the next time you remove blood from the aorta during MUF.  As you will recall, oximetry values are a reflection of cerebral blood flow in the watershed area.  If you take away from that blood flow with a mechanical pump, the oximetry values will also decrease ... indicating reduced blood flow to the brain.
SMUF is extremely user friendly and simple to use. Check it out. It is listed in Pubmed under Simple Modified Ultrafiltration.
Gerard Myers
Halifax, Nova Scotia

Posted By: Prasannasimha
Date Posted: Jun 22 2009 at 10:47pm
I will be out of town for a few days and will reply when I return. Arterio arterial and to a greater extent arteriovenous MUF will filter the reservoir rather than the patient
As far as falling cerebral saturations if done @ 10ml/Kg it doesnt affect cerebral flow. It is only when it done at a grater amount or when done at a rate that induces hypotension  that cerebral flow is altered. In fact if done propelrly there must be an increase in pressuresand cardiac ouput. The key is slow translocation of extracellular water. If done rapidly it will only displace intravascular water leading to hypotension. We want to shift extravascular water intravascularaly as well as remove toxic metabolites of CPB.

Posted By: coleb
Date Posted: Jun 23 2009 at 8:58pm

SMUF?  We did a case today and did both A-A and A-V due to the fact we had to go back on pump.  Both work well but due to manipulation of canulas the surgeon is still not happy.  So I brought up SMUF and showed a diagram on how it might work.  We all think this may be something we are interested in doing. 

Can you walk me through your circuit set-up?  Do you just cut a HC in line of your arterial, drain slowly down your venous, into your reservoir, through you O2 and up through the HC into the patient?   Also how long do you SMUF?  We can usually go 10 to 12 min.  A-A.   Also very important, how do you maintain the patients pressure if you are hemoconcentrating back through your arterial?  Do you just run your arterial pump faster than what is coming down the venous?  And any other little details you can provide.  We have another kid tomorrow (24th).  If you get this please send back all info asap. 

Thanks in advance

Posted By: gmyers
Date Posted: Jun 24 2009 at 3:42pm
If you send me your direct e-mail address, I will try to walk you through the set up and send you some attachements with pictures and diagrams.
The set up is actually very 'simple'. 
Place a luered connector in your venous line (either 1/4" or 3/8") and attach a stopcock to it.  From that stopcock, put in a length of 3/16 tubing that will go back to a seperate roller pump (call it SMUF pump) and into the TOP of a pediatric hemoconcentrator. From the BOTTOM of the hemoconcentrator, run a length of 3/16 tubing to the inlet of the membrane oxygenator.   About 1-2 inches from the inlet of the oxygenator, cut the 1/4" tubing and put in a 1/4 x 1/4 connector with luer and a stopcock, then attach the hemoconcentrator line to this stopcock. That is it.
Before going on bypass and while circulating your prime, you can use this system (running from A to V) to reduce your prime and wash your blood prime to correct electrolytes and reduce lactate. During bypass you can use this system to perform CUF and monitor venous blood gases with a CDI500 by running in the V to A direction.
At the end of bypass, you clamp between the venous inlet of the oxygenator and the luered venous line connector to come off bypass (do not clamp the arterial line at this time).  When the surgeon tells you to SMUF, you turn on the SMUF pump at a rate of 20-40 mls per minute and draw from the venous line which now goes into the hemoconcentrator, through the membrane oxygenator, out to the arterial filter and into the aorta.  As you take fluid off through the hemoconcentrator the pressures will decrease.  To bring them back up you keep the SMUF pump running and slowly turn on the main pump to slowly infuse reservoir volume as you would in any MUF case. When the pressure stabilizes, turn off the main pump but do not turn off the SMUF pump.  Repeat this over and over until you remove 30-50 mls/kg of fluid or you see the hematocrit on your venous saturation probe increase to where you want it.  Once you run out of volume in the reservoir you can chase the remainder with 50 mls of added fluid until the venous reservoir is empty again.  Then turn off both pumps and clamp the arterial line ... tell the surgeon you are done and what the results are (time, vol off and hematocrit). SMUF times will depend on reservoir volume and patient size but usually it will run for 5-10 minutes.
I would suggest you try this once or twice without a patient until it becomes clear. Once you get used to it you can even use the system to hemoconcentrate the entire volume of the circuit once the cannulas are out and give the concentrated volume back to anesthesia in a bag.
You have to be aware that the main pump and the SMUF pump are connected to each other in the above manner.  We have become so used to it now that we run it throughout the pump run and even use it to retrograde prime the venous cannulas before the surgeon puts them in at the start of bypass.
Once again, please try it in the lab or the pump room so both you and the surgeon can get used to the idea.
Drop me a line at - and I will send you some info.

Posted By: rajev76perf
Date Posted: Aug 31 2009 at 8:39am
Hi Gmyers and Coleb
I also would like to share my technique of doing modifed ulterafilteration ,but without using any extera pump , we usually use two way i.v set for deairing pusporse after de-clamping  , the same i.v set is used for deraining and another i.v set for returning the filtered blood back.
SMUF connections are like that:
 venous cannulae(a)--luer st.or y connector conector with three way attached leter(b)----venous line(c).
now when u want to start muf just attach one end of i.v set with three way (b) and put a clamp between(b) and (c).and through another end u can drain directly through non filterd port into venous reservior with three way attached to control the inflow in case of hypotension.
connect art. filter purge line three way to hemofilter inlet(d) and from hemofilter out let three way (e)---attach i.v set one end to this three way and keep the direction of threeway such that all blood will be directed towards another end of i.v set  to return blood back which u can connect either to aortic cannulae luer connection or medikit used for cardioplegia delivery or into RA.
when u want to start the MUF clamp the art. line post art. filter .just turn the  threeway to take the blood  into the reservior ( non filtered port)and start the main arterial pump ---from oxygenator to art. filter ---purge line ----inlet of hemofilter .
 rest is same as GMYERS CIRCUIT.with this circuit u can use venous line blood too for filteration and keep even continue with supplying filter warm oxygenated blood without any problem with venous reservior blood.keep target of taking water out from hemofilter around 10-20 ml/kg or time of 7 -10 min.with this target u can easily achive the desired hct and lees pvr postoperatively. at any moment of time u can go back on bypass just simply taking iut the clamps at venous and arterial lines. please do share u views how did u find this .
Rajeev Gupta

Posted By: dragosmodiga
Date Posted: Sep 18 2009 at 3:08pm
    I don't know if you're doing MUF every single operation or only on the complex one, but anyway, after a surgical repair, having in mind the delicate moment  for the pediatric heart when you're performing MUF, in my personal opinion someone should follow a very carefull and " phisiological" way of filling this heart avoiding as far as possible to increase the afterload, all this being a pro for the A-V MUF
P.S. Even if it's a loosing volume procedure, it's about where the inflow is at that very moment

Posted By: dragosmodiga
Date Posted: Sep 18 2009 at 3:50pm
  I totally agree with Prasannasimha. First of all, the littlest contact with the ECC is mandatory for avoiding the complement activation(you don't need some more of this stuff, right?) It was one of the basic rules when the MUF started. Secondly, the MUF flow is insignificant respectly to the LVO

Posted By: merry-shopping
Date Posted: Jan 06 2010 at 5:25am
happy new year

Posted By: jormoltx
Date Posted: Mar 27 2012 at 2:14pm
AA MUF was introduced by Mehta, Millan and Molina at the AmSECT 2006 meeting in a poster as an alternate if aortic root venting was undertaken for a long time.  We simply drained the venous line, sucked aortic root blood, hemoconcentrated it and pumped it back just proximal to the MO (conducer with 1/8" tubing) and distal to the MO when the levels were zero until the blood turned light colored.  No venous lines simply a 1/8" venting tubing-roller head-HC-preMO/postMO-aortic line.   Jorge Molina :)

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