BFR- for nocturnal and depending on what dialysers?

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1

Hello. My husband is using a polyflux 21L dialyser. He does Nocturnal dialysis every second night and does 8 hours.

He was running his blood pump (BFR) at 250. But, since reading the manufacturers book on this dialyser it says to run a BFR at a minimum of 300 and maximum 500.

Do, you think running at 300 is to much for nocturnal patients?
He did run it last night at 300 with AP-160. VP-100. without any problems, we were just wondering if 300 was to fast.

thanks for your replies :roll: :slight_smile:
Queenie.

2

You should of course check with your home dialysis nurse, but this is what I know about it. I do daily nocturnal.

First, are you sure the dialyzer data sheet is talking about blood pump speed? The instruction sheet that comes in my boxes of Fresenius dialyzers says that the UF rate should be no less than 300. It doesn’t say anything about blood pump speed, and I don’t see why it should, unless the idea is to reduce the possibility of clotting in the dialyzer. The recommended minimum UF rate is to prevent backflushing of dialysate into the blood circuit. However, it’s common to run nocturnal treatments with a UF rate less than 300, and our technical people here now say that it’s not a problem, as there is always a bit of backflushing anyway (and that’s OK because more attention is paid to dialysate water quality nowadays - in addition to the R/O, Fresenius machines used at home here have a special “ultrapure” filter).

But whatever it says, in my home hemo program, they routinely prescribe a blood pump speed of 300 ml/min for nocturnal. This is really more of a maximum, and running it slower is Ok if you have lots of pressure alarms. But if you run it too slow, the needle pressure numbers will be low, and there’s a greater chance of clotting during treatment. Another disadvantage of slower blood pump speeds is that you get less dialysis in the same given amount of treatment time. So, ideally, blood pump should run at 300 unless that gives arterial or venous pressures that are too high (the number itself, not looking at the negative or positive sign). In my case, I’ve run it as low as 250, but the pressures are kind of low when I do that.

So… no, a blood pump speed of 300 is not too fast. If your husband is doing nocturnal hemo but only every other day, then, if you run the blood pump too slow, he won’t be getting much better dialysis than he would during a 4 hour in-centre treatment. For example, let’s say in-centre he runs at 400 (which is typical) for 4 hours. Well, if he runs at 200 for 8 hours, he’s not getting any more dialysis.

The idea of slow blood pump speeds (slower than 300) is kind of obsolete now. They originally did that because the were afraid the long treatments would cause depletion of various essential things like vitamins, minerals, etc. But many years of clinical experience with daily nocturnal has shown that this is not the case. So now, they recommend a blood pump speed of 300 in order to maximize the amount of dialysis the person gets overnight.

Do check with your nurse though, as there might be special circumstances I’m not aware of (and I’m just another patient, not a nurse or doctor).

Pierre

3

Thanks Peirre,
for replying.
I have just rechecked the General information sheet that comes in the box for the polyflux21L dialyser. It says blood flow rate between 300-500. UF rate should be <130 with a BFR at 300.

It does say in bold letters. " DO NOT preform a treatment outside of the min or max values listed below. BUT, it doesn’t say why :slight_smile: hhmmm… It has me wondering now.

I want to thank you for all the information because you reminded me of somethings I had known and forgotten. :slight_smile:
Queenie.

4

I respectfully disagree with some of Pierre’s statement. When nocturnal dialysis began in Canada and the U.S. it was believed that a slower blood pump speed is easier on the heart. To my knowledge this belief hasn’t changed. The slower blood pump speed was possible with daily nocturnal as you were running long enough to get a good treatment at a slower speed.

5

Pierre:

The instruction sheet that comes in my boxes of Fresenius dialyzers says that the UF rate should be no less than 300. It doesn’t say anything about blood pump speed, and I don’t see why it should, unless the idea is to reduce the possibility of clotting in the dialyzer. The recommended minimum UF rate is to prevent backflushing of dialysate into the blood circuit. However, it’s common to run nocturnal treatments with a UF rate less than 300, and our technical people here now say that it’s not a problem, as there is always a bit of backflushing anyway (and that’s OK because more attention is paid to dialysate water quality nowadays - in addition to the R/O, Fresenius machines used at home here have a special “ultrapure” filter).

In-center they have a new protocol that the UF can not be turned completely off temporarily (5-15 min.) when low bp or cramping occurs which is what has been done for yrs. to give the body time to rest to give up fluid- now UF can only be turned down to minimum which is 300. We asked and their concern is re backflushing, but no one knows why suddenly now unless it is a corporate decision to protect liability. So, the question is, just how serious is backflushing?

6

I don’t come up with these things on my own :slight_smile:

This is what the nephs are saying here. A pump speed of 300 ml/min is already fairly low compared to most in-centre hemo. But as I said, some people might have special circumstances (like heart problems, for example). The only reason I can think of for a dialyzer manufacturer to recommend a minimum blood flow speed is probably to prevent clotting in the membranes. Other than that, what matters most to a dialyzer is transmembrane pressure (which itself is a function of UF).

SLOW DIALYSIS: relatively slow blood speed (no more than 300 ml/min), slow dialysate speed (300), slow UF rate (usually around 400 ml/hr or less).

But local technical experts sometimes have different ideas than the original manufacturer, so, I just do what they tell me.

Pierre

7

Hi Queenie
In answer to your other query, I also live in NSW and my Neph is quite happy to up my nights on Dialysis from 4 to more if and when i want or need to. So… I think it depends how much sway your neph has with your hospital and how tight the hospitals budget is. There are NSW patients on 4+ nights a week so we need to keep pushing the envelope to get the best individual patient outcomes.
I regularly use 225- 250 blood pump speeds as I feel better on these speeds and use high flux FX60 dialysers. My results are great so far (although I am sure not as good as Pierre’s who does daily Nocturnal. But for me 3-4 nights a week makes me happy at present.

Have you seen John Agar’s site http://www.nocturnaldialysis.org

Question and quote from Agar’s Website
[ You use lower NHHD flow rates than we do – why is this and aren’t high flow rates beneficial and necessary?

Your question says you use a blood flow rate (Qb) of 300 ml/min and dialysate flow rate (Qd) of 500 ml/min. We use an average Qb of 225-250 and a Qd of 300. The following reasons underpin our decision …

Initially in 1993-4, when Uldall and Pierratos began the first NHHD program in Toronto, they used a program of 8 hr dialysis/treatment, 6 x week and a Qd of 100 and Qb of +/- 250.

When I visited in 1999 and decided to ‘import’ his program to Australia, he only recently had increased the Qd from 100 to 200 and finally to 300. We chose to use 300 based on his experience at that time.

Since then, others have used even higher rates - see below - but remember, our two programs (Toronto and Geelong) are based, in the main, on 6 treatments/week whereas many of the more recent ones are alternate nights (7/fortnight or ‘3.5’/week). The less frequent the dialysis, the greater the need to up-regulate flows to compensate for the loss of time and to ensure adequate dialysis.

So, what are the positives and negatives of all this?

Clearly the greater the Qd and the Qb, the more efficient the dialysis … but we already were achieving super-efficient and effective dialysis. Our patients’ Kt/V’s (the current ‘measure’ of dialysis efficiency which, incidentally, I do not believe in for a moment nor agree with at all) were far in excess of those achieved by CHD. Our patients were reaching a glomerular filtration rate (GFR) equivalent of 50 ml/min. 2 normal kidneys produce a GFR equivalent of 100 while CHD produces an equivalent of 13 and chronic kidney disease (CKD) just before entry into a dialysis program is usually equivalent to ~8-10. Compare 8-10, 13, 50 and 100 and you will see that NHD is achieving about 1/2 of normal two-kidney function whereas CHD achieves about 1/8th .

As such we felt no need to ‘push’ the fistula but to simply ‘cruise’ with gentle blood flows and a Qd which didn’t risk either the concentrate or the Bi-bag running out before the planned end of the treatment. The initial rationale for a low Qd was to extend the life of the treatment time and thus ensure bi-bag and concentrate continuity. Remember, our NHHD program is primarily six treatments/week.

As we have introduced patients to alternate night NHHD (7 nights/fortnight or ‘3.5’ nights/week) as well as 6/week NHHD… and here I stress my very strong belief in 3.5/week not 3/week regimes, we have kept our initial Qb and Qd regime for no better reason than it was in our protocol! OK, I know this is not a good scientific reason, but it is truthful! Despite this, we are very happy with our phosphate control, dialysis efficiency and other parameters under both options so I suppose there has been no driving cause to review or change.

As for why higher flow rates are beneficial? … simply, the more ‘passes’ that occur between blood and dialysate, the more efficient is the solute removal. There is therefore some theoretical benefit from both a higher Qd and Qb but if one only - which?

Well, a Qd of 500 compared with a Qd of 300 significantly raises solute removal whereas increasing Qb from, say, 250 to 300 has only a small effect on efficiency - certainly a correspondingly smaller effect than changing Qd. In addition, I have a personal belief (founded more in my experience and ‘gut feelings’ than in my scientific head) that higher AVF flows don’t do the fistula much good. So … if a Qb of 225-250 gives good numbers and outcomes, I think I am justified to be happy with it. In my view then, if one flow rate is to be increased, make it the Qd.} end quote

Cheers 8)

8

HI Beachy,
Nice to see some fellow Aussies on board :slight_smile:

I am not sure of the reason why our centre runs the Qd rate at 500. but it is my understanding as you have written above that it raises the solute removal. They haven’t proved either way whether this is true or not. As it says on Dr Agar’s website.
When I spoke to him in person at a Seminar a couple of years ago he said it can’t hurt and if you aren’t running out of bibag/dialysate fluid and if the machine allows you to have the flow at 500. ( the fresenius 2008) don’t. Con is using a fresensius 4008 ( boogie…lol )

We both agree with you that with higher AVF pressures it can’t do the fistula any good. Con’s are currently AF 160, VF 100. The Neph has told us that these are good. Anything under 180-200 is ok.

Before he started on Nocturnal he used to run the Qb at 360. and the Qd at 500. He had great clearances. Have you ever had a pre and post urea test? This when calculated tells you your clearance rate. Con was getting 88% clearance, using a polyflux 17L dialysers.

Since going on to Nocturnal, they kept the machines Qd at 500. and the Qb at 250. But, he was changed to a Dicea 170 Dialysers. After testing his clearance rate it went down to 78% clearance. So, we had something to say about that and the doctor has now ordered he have a polyflux 21L. Turn the Qb up to 300 and leave the Qd at 500. We need to wait 2 weeks then, do a clearance test and see what it is.

My guess is that this will show whether turning the Qb up will make much difference and of course having a big surface area in the dialyser will make some difference.

After all that, as to your question why are the Qb and Qd so different to what you use. I don’t know :slight_smile: Does it make any difference? Well maybe not. :slight_smile: I will ask again at the next seminar we attend. There is one every year run by Sydney Dialysis Centre. They have a number of doctors attending, Dr Agar is the most informative. Its a great day. Very very informative in all areas of ERSD.

cheers Queenie.

9

Firstly, you shouldnt be following instructions on packaging. Whatever your Dx unit tells you to do, is what you should be doing. As far as I know the dialysers are no different for nocturnal, they may change to a different size though. I run at 225, which is what Ive been told. I would suggest you talk to your unit about this.

10

Hi Amba,
I have spoken to the unit manager about this and the doctor. The dialysers are the same, they just have different surface areas, and some are sterilized differently, hence why some people have reactions to certain dialysers. His Dx unit are happy for him to run the Qb at 300 and the Qd at 500 :slight_smile: ( the Qd rate is standard here in nsw on a fresenius 4008b) at his centre.

Also, it is good to read the manufacturers recommendations because there are reason why certain rules apply. Then, of course you consult the doctor because he knows best, most of the time. :slight_smile:

I posed the question "Do, you think running at 300 is to much for nocturnal patients? " to the group because it is good to get the opinions of patients who are actually doing this form of dialysis.

I appreciate everyones input,
thank you very much for taking the time. :slight_smile: :slight_smile:

cheers Queenie.

11

Queenie, I am on nocturnal thats why I answered. We run the flow rate at 500. Im on a 170H dialyser.

12

hi Amba,
I think we are confusing each other…lol…
what I mean by running at 300. is the BFR. ( the blood pump).
Cons flow rate ( dialysate flow) is at 500 also. The same as you.

I just thought orginally that having the BFR at 300 was to fast for nocturnal dialysis, but since speaking to the nurse. She has said it is good. :slight_smile: as long as the Arterial/venous pressures are good.

cheers Queenie.

13

I try to gradually raise blood pump speed to 300. Sometimes though, because the pressures are higher, it might cause alarms as I move about during the night. If that’s the case, it will usually happen during the first hour, and I just decide to turn it down to 275 or 250 for the night. That usually solves it. As I tried to explain before, it’s not that critical for nocturnal since even at 250, you would be getting plenty of dialysis. Just look at total blood volume after treatment if your machine displays it. For example, the night before yesterday, I ran at 300, and I ended up with a blood volume over 135 litres. Last night I ran at 250 because for some reason, my venous site was sensitive to movement, and I ended up with a blood volume of 110 litres. That’s still a lot of times through the dialyzer.

So, don’t misunderstand me. I’m not saying you have to run at 300. I’m just saying there’s nothing wrong with running that fast on nocturnal if you can - as long as your dialysis prescription allows it.

Pierre

14

HI Pierre,
Thanks :slight_smile: I think it is great that we can all talk to each other.

cheers Queenie

15

Sorry Queenie, I probly read your post too quickly. Im happy doing 225 BFR for nocturnal doing 10hrs. I have a bad tendancy to get rebounding potassium, so the slower speed is better for me. Plus my venous pressure wouldnt hold up if I were going over 250.

16

HI Amba, :slight_smile:
what is reboudning potassium? I haven’t heard of that.

Queenie.

17

I couldnt tell you the exact definition Queenie, but it is basically when you get a high potassium after dialysis which is your bodies response to it being too low, or from having short fast dialysis. As an example, when I was on 3x5hr treatment, it didnt take much for my potassium to go up between treatments. Naturally it will rise between treatments, but mine was so crappy that I could barely eat anything without setting it off. I counted my mmol to the very point, but it still went high. One doctor didnt beleive me and said “it has to be what your eating” pffft. I saw the dietition that many times, and was the first person to ever ask her for a detailed list of exactly how much potassium was in each food, so I could count it as accurately as possible. It doesnt happen to everyone though.

18

Heather, It’s backfiltration they’re referring too and it’s my understanding it can happen more readily with some of the new dialyzers, in particular the polysulfone types, ultra. Just watch the tmps and make sure they’re in range; that way you know backfiltration isn’t taking place. Lin.

19

Yet another nocturnal dialystor in Oz :smiley:
I use a 210H dialyzer…surely whatever the number is, is the surface area in square meters, so a 170L or a 170H or whatever else, will all be 1.7 M2.
I run at a b.p. of 250 and flow of 500. …I occasionally get TMP dropping & have to come off early, as the Fres’ 4008B does not allow running @ or below 0 (whereas the Gambro does), but that’s O.k. by me. I’d rather not risk it. 8) It means I get thru about 8-9l of acid (2 5l bottles decanted into a jerry can) & totally thru a 950g BiBag in a 9 hour session.

20

Pierre wrote

So… no, a blood pump speed of 300 is not too fast. If your husband is doing nocturnal hemo but only every other day, then, if you run the blood pump too slow, he won’t be getting much better dialysis than he would during a 4 hour in-centre treatment. For example, let’s say in-centre he runs at 400 (which is typical) for 4 hours. Well, if he runs at 200 for 8 hours, he’s not getting any more dialysis.

Beachy quoting professor Agar wrote:

Well, a Qd of 500 compared with a Qd of 300 significantly raises solute removal whereas increasing Qb from, say, 250 to 300 has only a small effect on efficiency - certainly a correspondingly smaller effect than changing Qd. In addition, I have a personal belief (founded more in my experience and ‘gut feelings’ than in my scientific head) that higher AVF flows don’t do the fistula much good. So … if a Qb of 225-250 gives good numbers and outcomes, I think I am justified to be happy with it. In my view then, if one flow rate is to be increased, make it the Qd.

I have to second professor Agar there is not a linear relation between the amount of blood processed and treatment efficiency. Increasing Qd is the lowest hanging fruit available to improving the value of each minute spent dialyzing.

As Jim Curtis wrote in the other thread –

The reason long dialysis treatments work so well on middle molecules is not so much the dialyzer membrane, but the human membranes. During your treatment, molecules must “dialyze” out of your cells to get into the blood stream. The larger the molecule, the longer it takes. That is why phosphorus levels are so much better with Nocturnal dialysis.

I think that is the value of long (and to a lesser extent more frequent) dialysis, not the amount of blood processed. Nocturnal gives time for molecules to migrate, from in and among the cells, to the blood stream. Worrying about the amount of blood processed (like the renal diet and post-dialysis washout) is a hangover from standard three day a week, short dialysis schedules.