Question about BFR with NxStage

My personal dialysis was improved with both time and increased dialysate. The NxStage operates on a part of the flow curve that is not yet maxed out and plateaued so increasing the dialysate does increase clearance as well as the time. You do need to be careful of potassium going low with higher dialysate. Once again, bring this issue up to the medical team. I do 40L in less than 4.5 hours without any problems and my clearance went from 077 to 0.9 in the same exact time frame. Good luck.

Dear Alaskagirl

We need to be cautious - especially those who, maybe foolhardily, try to do Q&A sessions (like this one) on the net - about offering direct comment on patient management and dialysis prescriptions. Management decisions are, must be and always will remain a contract of trust and obligation between a patient and his/her managing team. It would be wrong to ever regard it otherwise.

Nevertheless, you have, to an extent, already answered your own question by following the decisions that you have worked out with your managing team… the longer treatments, the higher heparin dose … and, given your comment that you ‘feel as though dialysis has taken over your life’, you have also already concluded (correctly in my view) that overnight dialysis is the way forward with your comment ‘I can hardly wait for nocturnal’.

As for the dialysate - it is one of the nice, warming things in my life as a doctor to see patients who, after intelligently considering their own programs, come to their own - and commonly correct - conclusions about things that might just make a positive difference to them and to their treatment regimens. You have been an example of that! Well done.

Peter Laird, a dialysis (and NxStage-using) patient who has already taken the path you are now treading - to his personal satisfaction and delight - has answered you wisely from his perspective as a ‘user’. Remember my earlier caveats about my personal lack of experience with the NxStage machine … again, I defer to those who know it better than I … and, as a result, any comments I make are offered only as broad observations. That said, one of the concerns I have had with the NxStage, rightly or wrongly, is that it does tend to skimp on dialysate exposure. Much as I believe that more is better with dialysis as a whole, the same could be said for the dialysate.

In my view, you are on the right track. But, please, discuss it with your team first. Always do ‘stuff’ with your team and never against it, and never without their blessings and agreement. One of the best rewards in dialysis - both for the patient and for the treating team alike - is gained from mutual learning, each from the other. Here is your chance to softly, carefully bring your team along with you, so that you can both learn and grow together.

John Agar

Dear Dr. Agar,

Does body weight in any way affect BFR when it comes to nocturnal txs? Specifically, can a large bodied person run at a BFR of 200?

Body Weight and BFR

No, there is no special relationship between BFR and body weight that I am either aware of, nor which I can conceive might be required or of any practical importance in nocturnal dialysis.

The simple beauty of nocturnal dialysis … and here, the word ‘nocturnal’ implies a through-the-night, sleep-through dialysis regimen - and that implication, in turn, implies long duration therapy and, further, that implies (in our Geelong program at least, though I am aware this may not be true of all programs) an 8-9 hour mean run time … the simple beauty is the capacity to wind down the volume removal rate (the UFR) and the fistula ‘flog’ rate (the BFR).

I like the thought of that! It is more physiological. It is gentler on the body. It exerts less sheer-force on the fistula endothelium (the vascular lining cells).

I believe in a simple adage - an adage exemplified by nocturnal dialysis … if you don’t have to flog the system, then don’t.

Further, the more frequently the long, slow, overnight treatment is given, the happier I am … and the better-off the patient’s physiology will be.

In this milieu of long, slow, frequent (extended hour and high frequency) dialysis, even a very large patient won’t need to ‘rush’ stuff. I simply don’t see the need for it. What might be lost in efficiency by a slower BFR (at any body weight) will be more than compensated (at any body weight) by the greater efficiency exerted though extended dialysis duration in the removal of solutes from deeper body compartments (Eloot - from Vanholder’s group in Belgium - performed a series of elegant experiments using the Genius System … see "Kidney International (2008) 73, 765–770; ‘Impact of hemodialysis duration on the removal of uremic retention solutes’) and, if greater dialysis frequency is also built in, better again!

It is only in the US that ‘excessive’ (my word, my view) BFR’s are used. Only in the US. Why? Because your dialysis programs have embraced short-hour (and sometimes very short-hour) treatments - so it simply has to be wham-bam, bazooka dialysis, just to ‘make ends meet’ regarding solute and fluid removal. That means US patients are ‘conditioned’ to accept big everything … and especially big BFRs and big UFRs. But, that don’t make 'em right.

As for actual BFR in ml/min … we started our NHD program @ 200-225 ml/min. Our NHD patients (broadly) now run their BFR @ 225-250 ml/min. Our conventional patients run a BFR of 275-325 ml/min though most are @ 300-325 ml/min. 200? for long duration treatments … I’d say, why not?

Ray Vanholder, a most eminent Belgian dialysis expert, has written much on the factors that influence dialysis efficiency. From his work, the following factors are (among the most) significant:

Solute related factors:

Compartment solute distribution, Intracellular solute concentration Resistance of cell membrane, Solute protein binding, Electrostatic charges, Molecular steric configuration, Solute molecular weight

Patient related factors:

Distribution volume and body weight, Solute intake and generation rates of solutes, Metabolic solute precursors, Residual renal function, Access quality, Absorption rates from the intestine, Hematocrit, Blood viscosity (+/- blood rheology)

Dialysis related factors:

Dialysis time, Dialysis frequency, Interdialytic intervals, Blood flow rate, Mean blood flow rate, Blood flow patterns (within the dialyser), Concentration gradient, Dialysate flow, Dialyzer surface area, Dialyzer volume, Dialyzer membrane resistance, Dialyzer pore size, Adsorption onto the dialyzer membrane or onto other constituents of the dialyzer circuit, Ultrafiltration rate, Intra-dialytic changes in efficacy, Blood pH., Heparinization, Free fatty acid concentration.

I have quoted Ray Vanholder, here, to make a point … there’s a whole lot happening during a dialysis treatment that affects dialysis efficiency. BFR is but one of these factors.

So, yes … it does matter if the BFR is lower - a bit - but it isn’t the be-all and end-all. A lower BFR will be more than canceled out simply through adopting a longer dialysis time and, in general terms and while not referring to any specific patient when I say this … … and some!

So, I’d be comfy with a gentle BFR in any weight patient if the other (more important) criteria of duration and frequency and dually met.