Pump speed 480? WTH? 1st day on NxStage, Very worried

Ok so I had my first NxStage training today and I have a couple of questions.

One they wanted to run the pump speed at 480 :shock: I never run in center higher than 400, I have run 450 before though. Well I insisted that they lower it to 450 at least. At my old center I ran on a Fresenius machine. They say that the machines are different and 480 is normal, is that true.

Also, I am worried about the venous and arterial pressures. My arterial pressure was 190 at 450 pump which is similar to my in-center machine BUT my Venous was 240 and she said that is fine but I usually run 120-140 at 400 pump speed. Again they say different machine. Is that true?

I also want to know the “Good” parameters of the art/ven pressures while using a NxStage.

Overall I felt ok afterward, I ran 2.5 hours and only removed 1.5 kilos however that was my goal. The machine never beeped once and it was smooth sailing.

At first they insisted they stick me, so they get to know the fistula and so I let the nurse do the 1st needle and she did not get it, so I grabbed it and got it right in (after I went deeper), she did not go deep enough. I will never let them stick me again.

Also I spoke with the Nxstage rep and he assured me that the lines have a med port for epogen injection, but the lines used today did not have a med port. So I did not get epogen today. I refused it while they figure out a protocal for giving me epogen through the line at the end after they unhook me from the venous.

I would appreciate a reply from any Nxstage patients who know about these issues.

Overall it is VERY intimidating. And I am worried it may be to much work.


  • Epoman

First let me just say - way to go. I switched to home after 11 years incenter so I know that you must have self-motivated yourself to try something new. I do not use the NxStage but I always tell people to give it some time. A couple weeks any ways.

With the different pressures that could be the machine and it does seem odd that the absolute value of the venous pressure is higher than the absolute value of the arterial pressure. Jim Curtis where are you?

The blood pump is another matter all together – 480 ml/min means the same thing no matter which machine you’re using. My reaction is the same as yours, I wouldn’t have done it either. I use to run at 450 then in about 1996 when I started interacting online and hearing the stories of successful dialyzors I asked to lower my pump speed and increase my time. Since 1996 I’ve run at a 350 pump speed (the online edition of the Atlas of Diseases of the Kidney: http://www.kidneyatlas.org/toc.htm Chapter 5, Section 3 explains High Efficiency and High Flux dialysis. The Atlas notes that High Efficiency Dialysis is defined as having a blood flow rate greater than or equal to 350 ml/min, and a dialysate flow rate greater than or equal to 500 ml/min.)

This pump speed questions goes to the heart of my standing questions about the NxStage system – the dialysate flow rate. Doesn’t the constraint on the dialysate flow rate create issues? With the dialysate flow rate constrained the only way to increase the treatment impact is to increase the blood pump speed or increase treatment dose (time or frequency). Is anyone who’s been on the NxStage for over a year doing less than three hours?

I haven’t been on it over a year yet only 7 months. However I run my pump at 500 and take off an average of 2 kilos every treatment. I do only 4 treatments a week for now, may change next week, having a prob with phos and potas.

How long is each treatment? And how much dialysate do you use per treatment?

A 500 ml/min blood pump speed is fast. Did you start at that speed or build to it?

Sorry for all the questions Troy but I’m trying to understand the choices the NxStage requires - the high blood pump speed strategy seems myopic.

With the NxStage you can easily speed up or slow down your pump speed but it will change your parameters, and will lengthen the time of your treatment. When setting up you can play with it and see how long your treatment will be. How much dialysate do you use? Also the amount of fluid you remove affects the time, it is not like the Fresenius where your treatment is always X hours. Here bfr and fluid removal affect the overall time, but not by major minutes. I range from about 2:55 to 3:12.

I can get more technical but it really isn’t important.


Sorry, forgot about the two other questions:

Epo. Even on the Fresenius I did not do EPO through the port as it is much more effective if given subcutaneous. The needle is soooo small you don’t even notice it. I would guess if you refuse to take it that way, there is no reason why you can’t just add it to the lines as you do the heparin.

Pressures: Yours sound pretty good. Did you notice that the venous went down after a while, mine does.

Not too sure about what was so intimidating and so much work. I truly can set up my machine, wash, pull tapes, and be dialyzing within 30 minutes with at least 10 of that sitting around. Maybe we can give you some pointers. Maybe the Aksys would be a better choice for you as there is minimal set up.

home hemo 9/04

Absolutely, Cathy is right…Epogen is given subcutaneously here as well, results are much better than give through lines, the 1cc epo needles are tiny, you barely feel them…however, there are some patients giving it to themselves through the venous port on top of dialyser, using an extension.

As for pressure, they always start a bit high for the reason your sitting up, but after you raise your legs and relax it all normalizes…

I think Cathy suggests the right choice, for people on wheelchairs the Aksys would be a good choice, less supplies to deal with, but if your in apartment and don’t have extra room for water treatment and modifications and perhaps the landlord might not want the extra modifications, it might be a problem. On the other hand NxStage has a new addon module called PureFlow SL which eleminates the need of the bagged dialysate…prolly by end of year they will start shipping to all NxStage users who are interested…

As for the blood pump flow speed I first started at 370 for several months and now I run it at 420-450 …if you don’t feel well at 480, you can turn it down.


As for the blood pump flow speed I first started at 370 for several months and now I run it at 420-450 …if you don’t feel well at 480, you can turn it down.

How many hrs did you run for initially?

Do you still run the same time or less?

What is your dialysate flow rate?

What is your dialysate flow rate?


Does that equate with in-center rate of 500?

Do you know how to figure how long we would have to run using a blood pump speed of 350?

Dialysate in a conventional system does not run through the dialyzer many times. Fresh water is purifed by a reverse osmosis water purifier, then through the ultrapure filter. Then it enters the dialysis machine where it is mixed with bicarbonate and acidified concentrates to form the required dialysate. It only runs through the dialyzer once and then it goes out the drain. Some dialysis centers may have some kind of water recovery system, but you don’t have this at home.

Dialysate flow rate for short daily hemo is usually 500.

Even NxStage must start with water. Whether the water is purified to “ultrapure” standard at a factory or on site doesn’t matter in the end.


Do you know how to figure how long we would have to run using a blood pump speed of 350?

For people going on NxStage its measured differently, your height and volume, not body weight…for example, for someone of about 5 feet tall… 2.5 -2.7 hours…for people taller than 5 feet at about 3.5 - 4 hours

We are learning all the time. We thought all SDD txs ran about 2-21/2 hrs.

Let me clarify this, In-center dialysate passes through the dialyzer alot more, not 15liters within 2.5 hours…

We don’t use water, just plug and play…eventually, we may soon use water with the new Pureflow SL… :slight_smile: [/b]

[/b] :stuck_out_tongue:

Still need an answer to the question how long would we have to run with a blood pump speed of 350 for SDD txs?

I just gave you an answer, you want an answer based on pump speed, its not measured like that for NxStage…

Well Gus, pump speed does matter, at a slower pump speed you need a slower flow rate to get your prescription ff, her prescription will be for a certain number of kilos of dialysate and an ff factor. Depending on how much she is removing and how fast her bfr is the dialysate rate will change.

I thought it interesting that you say yours is always the same, mine will depend on the speed I am taking off and ranges from 6.9 to 8.9 maybe you always remove the same amount per hour, but even then, when it finishes removing fluid you increase the dialysate rate don’t you?? I remove anywhere from 1.0 to 1.5 per hour and take off anywhere from 1 to 4 per treatment.

Heather, I tried to tell you earlier, but, we can only estimate. Call your training center and ask them to calculate it for you. Generally however, SDD is not done at a 350 pump speed you will be doing daily dialysis for probably 3 hours or so at that flow rate unless you are a very tiny person. And Gus, weight and height do figure into the prescription not just height.


Cathy my understanding is that the NxStage has a filtration factor (Ff) that is set by the program – for instance the Northwest Kidney Centers uses a filtration factor of 35 or .35. This is the unique setting on the NxStage when compared to a standard machine. My understanding of the filtration factor is that it gives you the dialysate flow as a percentage of blood flow.

So with a Ff of 35 it means your dialysate flow rate would 35% of your blood flow rate. So to answer Heather’s question: Heather if you were at NKC (where they use a Qb of 350) and you were going to use a Qb of 350 ml/min the length of your treatments would depend on how much dialysate your doctor prescribed. If your doctor prescribed 20 liters of dialysate per treatment then you’d figure it this way:

Qb=350 x .35(Ff) = 122.5 = Qd (ml/min)
20 liters = 20,000 ml
20,000 / 122.5 = 163

So by my understanding your run length would be about 163 minutes. However. Cathy wrote that the amount of fluid that you are removing effects this calculation. Cathy does the your target fluid removal change the filtration factor? For instance if your filtration factor was 25 then your Qd would drop to 87.5 and your run length would be 228 minutes for the same amount of dialysate.

So there are at least three variables – the amount of dialysate, the filtration factor and the blood pump speed.

This is completely different from standard machines where the Qd is independent of Qb i.e. changing one does not change the other. On a standard machine there are studies that point to the improved clearances that result from increasing the dialysate flow rate relative to the blood flow rate. I have not seen any studies relating clearances to changes in the filtration factor. It would be interesting to see how changes in the filtration factor impacts clearances.

I think that the only way to shorten a run on the NxStage would be to increase Qd or decrease the amount of dialysate hung. In Epoman’s case I think that they proposed running Qb at 480 so that the run would be shorter. By running at 450 it made the run about 6% longer

Gus I don’t know what you’re talking about re: height. All I can think is that your conflating height with BMI but they are not interchangeable. At NKC they put the cut off for the NxStage at 90kg but they are probably using a BMI number and the 90kg is a rule of thumb approximation.

As Pierre states this is true for a conventional system, the Aksys PHD has yet another way to do it.