NxStage vs. Fresenius

I have mentioned in earlier posts that since starting the NxStage that my b/p and heartrate had returned to normal. Since I haven’t had a week of normal since starting dialysis, I considered this significant. Additionally I have felt so much better, lots of energy etc., just as I was told to expect with daily dialysis, but that I had never felt. I even made my son go out yesterday because I didn’t feel like hanging out at home, VERY unusual. What is odd is my clearances aren’t as good and my BUN is higher (still normal for dialysis 60 pre 28 post).

So, today I had to run again on the Fresenius. Yesterday my b/p was around 110/70, heartrate in the low 70’s. Started dialysis with a very normal b/p and heartrate (and also went on at the same time I have been treating with the NxStage so I am comparing apples to apples). By the end of treatment (slightly higher than dry weight as I wanted to be sure no one will say I went “too dry”) my b/p was 80/56 with a sitting heartrate of 98 and standing of 120. I am also shaky and weak with no energy and the inability to be up for long without feeling exhausted.

I really don’t know the reasons for this, but I think it is significant. I can’t wait to get back to my new machine and see what my pulse and b/p end up tomorrow after treatment.

Also, in case people are wondering, I was also extremely careful with fluid so only removed 500 more than usual in a longer treatment, inspite of it being two days since my last treatment.

I am not saying that the Fresenius isn’t a fabulous machine, it is, however, for some people it might cause problems.

home hemo 9/04
change to NxStage 3/06

Well, let me tell you, removing 500ml more is definitely significant. In a dialysis centre, when they want to adjust dry weight up or down to deal with blood pressure, a mere 500ml is usually the adjustment that makes the difference. We only have about 5 litres of blood in our bodies, so half a litre of fluid more or less can make a big difference. Since I’ve been on home hemo, when I’ve required an increase or decrease, I even been instructed to do it 200ml at a time - and I’ve seen the big difference in BP it makes. So, that’s definitely enough to make a difference.

Given that relatively small amounts like half a litre can make a big difference, is it possible that your weigh-in is different than when you’re at home? Clothes you wear at the unit vs at home could easily account for it. It’s very easy to suddenly weight half a kilo more because of heavier clothing, or less because of lighter clothing. If you happen to be wearing heavier clothes that day, you will in effect be taking off more fluid (you’re weighing more but it’s not fluid). Your eating patterns might also be different, or it could just be that the scales are different, giving different results. No two scales are exactly the same, and it’s not like they calibrate these things every day.

The other difference in how you feel is that there might be something that’s different in the dialysis prescription on either machine that isn’t immediately obvious. Dialysis is dialysis. If you’re getting wildly different results, something must be set different. Is the calcium the same? Bicarbonate concentration (well, I guess there’s no bicarbonate on a NxStage, so I don’t know what effect that change would have)? Sodium concentration? Seemingly slight changes can make a huge difference, in my experience.

I’m glad to hear you feel better, but I would be willing to bet it can be accounted for by something other than it just being the different make of dialysis machine.

Keep us posted. It’s very interesting.


I really think your getting a more gentle dialysis with NxStage low dialysate rates than the conventional dialysis that uses high dialysate rates…

Another factor is that daily short compared to 3x a week keeps an overall balanced state of feeling, whilst 3x a week fluctuates harshly making you feel dragged, drained, tired and horrible…

But also the dialyzer NxStage uses may also be a factor…

I wonder if anyone out there with a Fresenius can try lowering their dialysate rate close to NxStage and do daily and see what results given… :roll:

This would not be a good idea. Just looking at the ASN poster on the NxStage site shows how quickly clearances drop off as dialysate flow decreases.

It is hard for me to imagine how an increased dialysate flow would impact how you feel before or during dialysis. Blood flow would be a diferent matter but I assume you’re keeping blood flow the same. How could dialysate speed be “felt” by the body? That just doesn’t make sense.

Could you be sensitized to the standard dialysate? I don’t know if your symptoms could be the result of an immune response to the non-ultra pure dialysate but it seems possible.

I have experienced something similar in-center when I have been switched to a different machine. I wll be doing consistently well on my usual machine, but as soon as I am switched to an alternate machine, my dw and goal calculations do not work. I check all the settings on the machine and all checks out, but the alternate machine does not pull the same and I become hypotensive. Machine calibration can be different internally, where the machine is located in the loop is another factor as is the pressure flow into the machine, if the machine prescription is changed -all of these things can change the tx. Any of these things and other factors can change the way the tx is delivered and throw the calculated goal off. I can weigh the same as I did the tx before, wear the same clothes etc., but if the machines are calibrated differently it messes with the goal and will cause hypotension.

There certainly can be small variations between how closely-calibrated the various parameters are from one machine to the next in a dialysis centre. Everything is adjusted to a range, not necessarily and exact number. There’s an acceptable margin of error. I’m not a technician, but I know they calibrate things like temperature, conductivity, etc. Even once adjusted, these things drift over time. I’m not sure to what extent it would be enough to make someone hypotensive though. Sometimes it can be something as simple as dialysate temp. If the temp is lower, it will keep BP a little higher, and vice versa. All of the machines in use today have very fine regulation of ultrafiltration. But it’s not unheard of for a given machine to be off a bit. When a person is on daily hemo, it’s usually not necessary to have a dry weight which is at the absolute lowest it can be, unlike conventional hemo, and if so, small differences from one machine to the next shouldn’t be enough to cause serious hypotension.

I’ll try to reply to everyone at once:

First I have been using my weight only based on my home scale, I weigh prior to leaving and then weigh on their scale so I can tell the difference, then adjust, so I know that the weights there and the weight here at home are equivalent. I normally weigh in my nightgown, so to adjust for clothes I still weigh first in my “normal” night clothes, then get dressed (no eating or drinking in between) and then weigh again so I can adjust, I am Very, VERY sure that my weights are equivalent.

Second, the extra 500 is nothing, I used a lower u/f rate here today than I did at center using the NxStage. You must remember I have been having the low b/p and high heart rate for the entire 18 months I have been using the Fresenius. I have removed as little as 1kg and as much as 4kg a treatment (4 hours) and it has made no difference in my b/p and heartrate. I have also played with my dry weight and varied it by 5kg with no variance in my b/p and heartrate.

Gus, you knucklehead (said lovingly of course) I have been doing 6x a week treatments the entire time. I have never dialyzed in center, except for in my training center.

My bfr is much faster on the NxStage so should be “tougher” on me (450 vs. 350) however my Arterial and Venous pressures are much less on the NxStage than the Fresenius.

My “gut” agrees with Bill that there is something either in the Fresenius dialysate that I am reacting to, or something in their lines/kidney. I have also often had an increased white blood count since starting dialysis and even when normal it is around 10, which indicated to me that I was responding to treatments.

I do appreciate all the thoughts, and again, am not trying to bash the Fresenius, it just appears to give ME problems, and it might do the same to some others even though for most it works wonderfully.


This is all EXTREMELY interesting to us Freni users and we will be waiting for your next postings impatiently. Hope it all continues to look good for you.
Cheers 8)

Gus, you knucklehead (said lovingly of course) I have been doing 6x a week treatments the entire time. I have never dialyzed in center, except for in my training center.

Cathy, sorry…just forgot… :? …I guess am a knicklehead after all…

Btw, maybe its the dialysate…perhaps that’s what’s partly making a difference…

I was going to ask about your WBC - it is sounding like an immune response.

My husband is a dialysis patient of 4 years. We have just found information on the NX stage and are very interested. I am looking for responses from users of this unit and the pros and cons of the machine.

Hi Beth,

there’s alot of information already on this messageboard, if you search the board you will find lots of threads about NxStage System One…just visit this link below to search the board…


If there’s un-answered questions about NxStage just post your questions!

In regards to heartrate I’d not heard anyone note a difference Cathy, but I’m glad you did. I had a heartrate problem during txs. and ended up in the hospital for five days. If the Nxstage can help with that, that in itself will be worth the effort. Lin.

Cathy writes:

You must remember I have been having the low b/p and high heart rate for the entire 18 months I have been using the Fresenius. I have removed as little as 1kg and as much as 4kg a treatment (4 hours) and it has made no difference in my b/p and heartrate. I have also played with my dry weight and varied it by 5kg with no variance in my b/p and heartrate.

This is really interesting. Do you gain or lose real weight often or stay pretty much the same? What does you conductivity and ph usually run? Are you PKD…could that have anything to do with it?

As I mentioned, previously, I have dialyzed on the same FR machine tx after tx and the first time I am switched to an alternate FR machine I become hypotensive. Similarly, I have dialyzed on the same FR machine for months and feel fine during txs although post tx I feel very tired, but ocassionally on this same machine feel wonderful post tx, so much so that I desire to skip right off and go out to supper. And also, I was critlined once on a FR and felt incredible post tx, too. So, is it that I don’t do well on FR or is it that the tx peramiters/prescription is not individualized accurately to my needs?

In my personal experience, I have yet to meet the nephrologist, nursing staff or biotech who has good insight into individualizing the tx. And, I have had numerous nephrolgists tell me that such is not possible in-center so they don’t concern themselves with it. This, in my opinion, is pretty sad. Does this go on in other fields of medicine…maybe it does, but not so much as in dialysis?

It could also be, that some machines, dialyzers/lines and solutions are more compatible with patients overall, more technically balanced. Would be nice to hear from those who know, but they are few are far between…



I definitely think you have it right. I have used NxStage, AKSYS, and Fresenius units for tx and until I had a NxStage tx I thought all treatments are going to leave me feeling lousy when I was done. I don’t really know why, but like you my clearance is a little higher on NxStage. After 2 months of using NxStage I hope I never have to use another machine. I’m not worried so much about numbers I think how you feel is important.
When I was in clinic I remember I would ask them to run an extra bag of saline because if they didn’t I would get a rash soon after I came off. Now I just run a normal run on NxStage and I don’t have this problem. I didn’t seem to have a reaction when I was on AKSYS but even after an AKSYS tx I would feel run down after treatments. I don’t know if the rundown feeling could be a chemical reaction but I think there is a possibility.
I wish doing dialysis was like buying a car, test drive first then I think everyone could find a machine which is right for them.
I don’t know about anyone else but I have found with NxStage I can run a blood flow rate of 470 w/o a problem and I usually do. I could only run about 400 on AKSYS and 420 at clinic. I wonder if other NxStage users have seen this as well. Even at 470 my pressures run about A-200 V-180 and E-210 that seems pretty good for me as long as these numbers correct and not varied from one machine to another. Unfortunately I still would like to get better clearances with NxStage and I’m not sure how we can resolve that issue.

Bruce K.
Transplant 79’ 95’
Dialysis Feb 05’
NxStage Feb 06’

If and when NxStage gets their nocturnal version going this could help with clearances.

From what we heard it is possible to do nocturnal txs on NxStage currently with a stand alone heparin pump and your neph’s ok. Ask your rep.

Bruce, you can better your clearances by either slowing down your blood pump speed or possibly slowing down your u/f and running longer. My kt/v is actually quite good at .78 (look for a different number on daily, they want above.5). My BUN is just a bit higher, pre was low 50’s post low 20’s, so actually quite good for a dialysis patient. I am a large patient above 100 kg, so I am happy it is working well, it was a concern. I use 24liters of dialysate and an ff of 33, what is your prescription??

I’m happy you are doing better on the NxStage too. I do believe it is possible that different people have different experiences with the machines. All I know is that in spite of all the supplies and those heavy bags, I am looking forward to having some energy again and knowing how I was supposed to be feeling these last 18 months.

Cathy who comes home with her machine tomorrow!!

Cathy, once you get home on your first day with NxStage don’t forget to take some pictures of your first day!

Glad its working out for you!..