Patient's question put me on the spot!

tyloo · Mar 4, 2012

So a patient asked me, "If my BFR is at 450, wouldn't 500 do the work that much faster?" Another machine was alarming so I told him I would get back to him shortly (I really felt like I was saved by the alarm). I'm pretty new to dialysis but this made me realize that I need to read more and know my stuff! I went back over to him and he had turned his machine up to 500. I told him that the high BFR increases his AP and too high of an AP could cause hemolysis and also that he needs to speak to the MD about changing his prescription. This pt is very intelligent and imparts his knowledge on all of us, including the MD, so I'm thinking that he was just testing me. Regardless, I have never responded well to being "put on the spot" and I am going to try to be more prepared next time.

BFR is the blood flow rate per minute. It is the amount of blood being pulled into the machine and circulating through the dialyzer per minute. The higher the blood flow rate the more blood is being cleaned. So yes if the BFR is 500 it is 500cc/min there would be more LP (liters processed) at the end of his treatment compared to a rate of 450cc/min. However the highest BFR I have seen is 450. I have never seen a BFR past 450.

You are right it may have to do with the arterial pressure being to high. There is only so much blood that can be pulled from the access. You know how some catheters the BFR can only get as high as 350 or 400? The same for a graft and for a fistula.

jdethman · Mar 5, 2012

For 15g anything over 450 causes hemolysis, so you did well on the spot cheers

sharpeimom · Mar 5, 2012

there is never anything wrong with saying something like. "i don't know but give me a minute and i'll be glad to find out and get back to you." always better than trying to fake it for many reasons!

most people not only won't think less of you, but will be pleased by your candor and willingness to look something up just for them.

Chisca, RN · Mar 7, 2012

Higher QB's may cause more hemolysis due to the roller clamp crushing the red blood cells but that is not the reason higher flows aren't utilized. It is due to the effect it has on the heart, especially one that has a low ejection fraction, low cardiac output, or systolic/diastolic dysfunction. I have had many patients tell me they can feel when the QB is set at higher than 400/mn and it is not a pleasant feeling. So your patient may or may not tolerate a QB of 500 but he may be motivated to reduce his time on the machine if he feels he gets a better cleaning. If he can tolerate the higher flow I would try a QB of 500 but he will need to be monitored more closely for any distress.

Who?Me? · Mar 7, 2012

You are correct about the AP being too high. Is this pt's issue that he wants to finish his treatment faster?

Denroc72, BSN, MSN, LPN, RN, APN · Mar 8, 2012

With 14g needles, BFRs are obtainable at 550ml (AVF/AVG). Needle placement is also another reason that AP values can be elevated. If the AP is high with a CVC, then the positioning of the catheter, a kink, or just plain poor blood flow can affect it.

ICAN! · Mar 8, 2012

I believe he missed a tx and wanted more taken off during the same time frame.

Chisca, RN · Mar 8, 2012

Which is why higher flows are desirable at all, the belief that you can reduce treatment time by improving blood speed across the dializer. Mathematically it makes sense but it isn't reflected in dramatic reductions in urea or creatinine just an improved K/Tv. I am always a little nervous running patients at higher blood flows for the reasons I mentioned.