Is turning the utrafiltration off ok?

Specialties Urology

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I know that if a person is crashing or cramping etc that it is acceptable to turn the uf off until the patient is stabilized then turn it back on. My question is can you leave the uf off for an extended amount of time without having any harmful effects or decreasing clearance? A lot of nurses that have many years experience say not to but there are doctors now that say it is ok. Can anyone explain the different reasonings for this?

I've done some searching (why is it so hard to find good information regarding dialysis?!), and it sounds like backfiltration became a concern with the switch to high flux dialyzers. When you do the math, there is nearly always backfiltration with high flux dialyzers unless the UFR is very high. That's why the AAMI lowered the acceptable bacterial levels from 2000 to 200 CFU/ml, to prevent blood contamination. To make a long story short, there will still be backfiltration even with a UFR of 300 ml/hr or higher.

I've also looked through the Fresenius 2008K operator's manual, and there is no reference to a minimum UFR of 300. Can anyone refer me to this recommendation?

One more thought - if solute drag with ultrafiltration affects clearances that much, why do we do sequential ultrafiltration and SCUF?

Specializes in Dialysis.

I think one of the ways that Fresenius machines deal with backfiltration with high flux dialyzers is by altering the pressure on the dialysate side. The high flux dialyzers have larger pores. Selecting the high flux mode on the machine panel changes the TMP alarms from 70 to 300. Even with the UF completely off the machine is applying some hydrostatic pressure to prevent water removal from the blood so maybe that prevents backflow.

One more thought - if solute drag with ultrafiltration affects clearances that much, why do we do sequential ultrafiltration and SCUF?

Both of these modes are for water removal only so clearances of solutes are not an issue.

Specializes in Nephrology, Dialysis, Plasmapheresis.
I've done some searching (why is it so hard to find good information regarding dialysis?!) and it sounds like backfiltration became a concern with the switch to high flux dialyzers. When you do the math, there is nearly always backfiltration with high flux dialyzers unless the UFR is very high. That's why the AAMI lowered the acceptable bacterial levels from 2000 to 200 CFU/ml, to prevent blood contamination. To make a long story short, there will still be backfiltration even with a UFR of 300 ml/hr or higher. I've also looked through the Fresenius 2008K operator's manual, and there is no reference to a minimum UFR of 300. Can anyone refer me to this recommendation?[/quote']

Maybe the recommendation is on the dialyzer itself instead of the machine? It may give specific recommendations for different machines. But I believe it had to do with the dialyzer itself.

Are you all confusing UF-off with UFR (UF- rate)???? Turning the UF off means no more fluid will be removed. Lowering the "rate" below 300 refers to the amount of K and Ca clearance.

Just an update - I had spoken to my clinical coordinator about this issue, and last week she showed me a letter from Fresenius (think it was dated 2005), the gist of which was that they say there is no harm in turning off the UF. I guess if the manufacturer says it's OK, then it should be OK.

Specializes in Dialysis.

Even though I'm a new nurse let alone new to dialysis, my manager, charge nurse, and fellow staff RNs have all stressed turning off the UF when the pt is in distress whether it be cramping or low BPs. Why continue stressing the body and heart on pulling more fluid if the BP is too low or the HR is too high? I'm still trying to learn what my pts can tolerate...41 a day is stressful :(

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