What is this?

I have never used the term 'back filtration'. Can you place this in context for me? (What was going on when someone used this term?)

Carol

This is when the UF is turned off during the tx or before the tx ends, supposedly it can have a wrong affect.

Roger:

I am so sorry, but I have never heard of this happening nor was I able to find any documentation of this.

Can anyone help me????
Carol

Back-filtration is a natural phenomenon that occurs during dialysis. Molecules cross the membrane in both directions regardless of chemical gradient. Some believe that since the advent of high permeability membranes, backfiltration is of greater concern because of the possiblity of endotoxin and other pyrogens crossing over into the blood while still others believe that it remains of little concern because the molecular size of the endotoxin is for the most part still too large to cross through the membrane.

thanks, Chuck!

Lin,

Though still possible, the likelyhood of a pyrogenic reaction being caused by endotoxin crossing the membrane is very slim.

As I stated above, "backfiltration" is a natural phenomonon that occurs constantly regardless of how high or low the ultrafiltration rate is. Many people feel that endotoxin passage through the membrane is of little if any concern because of the fact that most endotoxin is just physically too large to pass through the pores.

This is a problem we have for a particular patient with very low UF rates. It results in a continuously negative TMP, which causes us concern that backfiltration may be occuring. We haven't however found a solution, short of infusion physiological solution during the treatment, thus increasing the volume to be removed...any suggestions welcome.

What machine and dialyzer is in use?

What do you call a low UF rate? On another subject, what is the highest rate the UF can be set at for patients who come in greatly overloaded?

Backfiltration does occur during dialysis. However endotoxins may cross the membrane depending on their size. They are only parts the bacterial cell wall membrane. Polysulfone dialyzers can help eveviate this because they can help trap endotoxins. In regards to "too low" TMP.....depending on machine, always check the integrity of the transducer protectors and the monitor lines. These MUST remain dry.

When you say remain dry what do you mean? I have seen blood backed up all the way to the round TP fitting. The techs tell me that blood can't get in there. So how would it get wet?

"Dry" meaning just that. You should never have saline and especially blood in the monitor lines and NEVER on the transducer protectors. They are made of paper. If this is fluid in them, the pressures A & V may not be accurate and cause other issues....ie:TMP alarms. Technically, if the TP's get wet, the inside TP should be checked for the presence of blood to prevent cross contamination....This may be found in the CDC guidelines but I not sure. Hope this helps.
T

I am wondering why FMC educators are teaching new technicians that a wet transducer, even a small amount of blood, as well as blood in the monitor line, is ok. Several techs have stated, after training, while working on the floor, that this is not a problem. The general answer is when asking, "It will only hurt the machine not the patient'..

high Kuf dialyzers coupled with low weight goals typically run calculable tmps into less than 20mm/Hg. Page 80 in the operator's manual(the revision I have, revision E) section 3.2 at any rate lists 8 actions for the operators to do to solve the problem. the Last action listed is to contact your qualified technician. Operators, please consult manufacturer's instructions.