I would like to know your opinion about the possibility of reverse ultrafiltration during dialysis when using the hiflux dialysers with the volumetric ultrafiltrtion controlled HD machine. As we know one of the disadvantage of the Hiflux dialyser is backfiltration with the lower TMP( minimum ultrafiltration). When using the volumetric ultrafiltration controlled mechine there is no significant TMP changes noted with either higher or lower UFR.

quote:

Originally posted by Xavier:
I would like to know your opinion about the possibility of reverse ultrafiltration during dialysis when using the hiflux dialysers with the volumetric ultrafiltrtion controlled HD machine. As we know one of the disadvantage of the Hiflux dialyser is backfiltration with the lower TMP( minimum ultrafiltration). When using the volumetric ultrafiltration controlled mechine there is no significant TMP changes noted with either higher or lower UFR.

This is a topic that can cause alot of division in the dialysis community. Whether you like it or not backfiltration happens. Its just the way the pressure dynamics in a dialyser works. Since blood and dialysate flow in opposite directions (countercurrant) the will be a difference in pressures from the blood compartment and the dialysate compartment. At the top of the dialyser where the blood enters, the pressure on the blood side is usually higher than the dialysate side, thus no backfiltration. As the blood travels to the end of the dialyser it the pressure becomes less. At the end of the dialyser the dialysate pressure is at its highest, therefore if backfiltration is going to occur it will happen here. As you get closer to the middle of the dialyser you begin to reach a point where there is no backfiltration but that can depend on the dialyser being low or high flux. I recently attended a conference where a gentleman named John Sweeney from Baxter talked about dialyser dynamics. If you can get a hold of someone at Baxter who can get you a copy of his presentation its well worth it. John has been in the field formany years and has a gift for teaching in a way that is simple and easy to understand.

Thank you for giving a reply. I will try to contact Baxter for more information. whenever you get any information or presentation please send to me. My email xavierantonysg@yahoo.com

You are welcome to the group of hemodialysis technicians as well. Here is the URL please join with us.
http://groups.yahoo.com/group/hemodialysis/

From my experience, having used Fresenius H and K machines, both with Volumetric UF Control, if you keep your UF pump on at all time and maintain a negative TMP, back filtration should not be a problem, especially on the K machine (if that is what you are using). If you are using K's during a low TMP alarm valve 24 closes to keep back filtration from occuring by keeping a negative pressure in the dialysate compartment. If it is a high flux dialyzer then the instruction sheet that comes with it should say to keep the UF pump on at all times. If it is routine to have a patient cramp up because of excessive fluid removal and it is imperative to turn of the UF pump then maybe they should be on a different dialyzer? Hope that helps you.

quote:

Originally posted by Xavier:
I would like to know your opinion about the possibility of reverse ultrafiltration during dialysis when using the hiflux dialysers with the volumetric ultrafiltrtion controlled HD machine. As we know one of the disadvantage of the Hiflux dialyser is backfiltration with the lower TMP( minimum ultrafiltration). When using the volumetric ultrafiltration controlled mechine there is no significant TMP changes noted with either higher or lower UFR.

I agree wholeheartedly about John Sweeney, He is the "man", a genius, as far as hemo machines are concerned. He has taught me a great deal since I started and he is also in charge of Baxter's Global training facility in Largo Fl. which has a museum devoted to Hemodialysis Technology,featuring the original Kolpff rotating drum machine.
go to: http://www.baxter.com/doctors/renal_therapies/techpubs/index.html

Anyway, the problems usually occur when you have a high Ultrafiltration rate on the dialyzer combined with low weight removal goals and long treatments. The machines can't handle the impossible, so the result is negative TMP, hence the alarms.
The only remedy is to lower the time, or raise the goal weight.
It really doesn't make a lot of sense to put a 98 lb. woman, with a goal weight of 1.5 kilos on a high UFR dialyzer and run her for say; 3.5 hours.
If you and I agree that it doesn't make sense, then that explains why your machines are alarming. They can't make it work either.
Just throwing a little Sweenyism at bro.