Comparison of Nxstage Clearance vs. Standard Dialysis

[obsidianom]

I found this article looking at actual dialysate clearances of solutes , comparing Nxstage to standard dialyisis. I have often wondered about the actual dialysate clearances of Nxstage and how it compared. This article proved that even with LOW volumes of dialysate , Nxstage compares favorably to standard dialysis. They were only using 15 to 30 liters at that time which is lower than used now on most Nxstage patients.


2010 Jan;14(1):39-46. doi: 10.1111/j.1542-4758.2009.00399.x. Epub 2009 Sep 16.

Solute kinetics with short-daily home hemodialysis using slow dialysate flow rate.

Kohn OF1, Coe FL, Ing TS.

Author information
Abstract
="NxStage System One()" is increasingly used for daily home hemodialysis. The ultrapure dialysate volumes are typically between 15 L and 30 L per dialysis, substantially smaller than the volumes used in conventional dialysis. In this study, the impact of the use of low dialysate volumes on the removal rates of solutes of different molecular weights and volumes of distribution was evaluated. Serum measurements before and after dialysis and total dialysate collection were performed over 30 times in 5 functionally anephric patients undergoing short-daily home hemodialysis (6 d/wk) over the course of 8 to 16 months. Measured solutes included beta(2) microglobulin (beta(2)M), phosphorus, urea nitrogen, and potassium. The average spent dialysate volume (dialysate plus ultrafiltrate) was 25.4+/-4.7 L and the dialysis duration was 175+/-15 min. beta(2) microglobulin clearance of the polyethersulfone dialyzer averaged 53+/-14 mL/min. Total beta(2)M recovered in the dialysate was 106+/-42 mg per treatment (n=38). Predialysis serum beta(2)M levels remained stable over the observation period. Phosphorus removal averaged 694+/-343 mg per treatment with a mean predialysis serum phosphorus of 5.2+/-1.8 mg/dL (n=34). Standard Kt/V averaged 2.5+/-0.3 per week and correlated with the dialysate-based weekly Kt/V. Weekly beta(2)M, phosphorus, and urea nitrogen removal in patients dialyzing 6 d/wk with these relatively low dialysate volumes compared favorably with values published for thrice weekly conventional and with short-daily hemodialysis performed with machines using much higher dialysate flow rates. Results of the present study were achieved, however, with an average of 17.5 hours of dialysis per week.

[obsidianom]

Sorry I screwd this up and reposted it.
I am interested in your take on this Hemodoc. I know you think Nxstage uses too little dialysate. Does this make you at least a little less concerned?

[Hemodoc]

Sorry I screwd this up and reposted it.
I am interested in your take on this Hemodoc. I know you think Nxstage uses too little dialysate. Does this make you at least a little less concerned?

Not at all, I am still quite concerned about the volume of NxStage dialysate and saddened that I cannot push to about 50 liters to improve my clearances because they have never addressed the sodium level of 140 mmols in all their dialysate preparations.

What they looked at was TIME dependent which we all know is how middle molecules and PO4 is removed. Obviously, looking at Kt/V, we get a different picture that is volume dependant.

When I first started in 2009 on NxStage, I got a Kt/V of 0.5 on 20 liters over about 3 hours, 0.72 remember correctly on 30 liters or close to that and 0.93 on 40 liters over 4 hours. Clearly, volume is an important aspect of NxStage as you know yourself from your wife's experience.

Why is NxStage increasing their volumes now and offering the upgraded System One S? Well, I believe in large part because all of the machines in development pending FDA approval right now in the US use volumes close to standard machines and much higher clearances.

NxStage is a good machine that does exactly as you state, clear middle molecules but it is not anywhere as efficient as the standard machines in clearing even the middle molecules. For 17.5 hours on the NxStage, you only get the clearance of 9-12 hours on a standard machine including middle molecule clearance. The message of the study you listed above is that of very inefficient machine that does need more volume for sure. NxStage will have a hard time competing with the outcomes of the next generation of portable home hemodialysis machines and they know that.

On the several occasions that I increased my dialysate, I felt much improved subjectively and my mind was much clearer than on my 40 liters. However, after two or three days, I could not handle the salt load.

Now, if NxStage makes 60 liters a standard dosage for all patients and lowers the sodium levels to avoid the salt load, then they will be very competitive with the other machines when you consider their ultra-pure dialysate.

The deciding factor for me apart from ease of use has always been the ultr-pure dialysate and that is still the case. Their lack of volume has always been troubling to me and still is.

[obsidianom]

Thank you, thats helpful. I did mention the sodium load to my contact in the company and tomorrow I have a pre arranged phone call with one of their top product guys. I intend to bring that up along with lowering the calcium as an option too.

[Hemodoc]

Thank you, thats helpful. I did mention the sodium load to my contact in the company and tomorrow I have a pre arranged phone call with one of their top product guys. I intend to bring that up along with lowering the calcium as an option too.

They won't lower the calcium which seems a priori to be the correct thing to do, but in fact, Brent Miller MD has shown with extended dialysis such as daily nocturnal, you must have a Ca level of 2.5-3.0 in the dialysate to prevent calciphylaxis. It seems the Ca level is where is should be. The sodium level is another issue.

[obsidianom]

Thank you, thats helpful. I did mention the sodium load to my contact in the company and tomorrow I have a pre arranged phone call with one of their top product guys. I intend to bring that up along with lowering the calcium as an option too.

They won't lower the calcium which seems a priori to be the correct thing to do, but in fact, Brent Miller MD has shown with extended dialysis such as daily nocturnal, you must have a Ca level of 2.5-3.0 in the dialysate to prevent calciphylaxis. It seems the Ca level is where is should be. The sodium level is another issue.

Their calcium is 3.0. I found an article that I posted and will repost here that lowering it to 2.75 is adventagious. I know it would help my wife who has chronic hypercalcemia.

Abstract
Because active vitamin D preparations and calcimimetics have been widely used to treat secondary hyperparathyroidism, maintenance of acceptable serum calcium and phosphate levels is important. A 2.75 mEq/L dialysate calcium product, which may bring the calcium balance closer to 0, has recently been launched, and we had an opportunity to examine its possible benefits. We performed a 6-month retrospective review after switching from 3.0 mEq/L to 2.75 mEq/L calcium dialysate in 85 outpatients undergoing chronic hemodialysis. We evaluated blood biochemical parameters, including predialysis and postdialysis serum calcium and phosphate levels, predialysis intact parathyroid hormone (iPTH) levels; dialysis dose (Kt/V); and doses of concomitant active vitamin D preparations, calcimimetics, phosphate binder, and erythropoiesis-stimulating agents. Postdialysis calcium levels were significantly lower and predialysis corrected calcium levels significantly decreased. The change in calcium levels before and after dialysis was smaller after switching of the dialysate than before. iPTH levels significantly increased 1 month after switching of the dialysate. No remarkable changes were observed in phosphate levels or Kt/V. The dose of alfacalcidol, one of the concomitant drugs, somewhat increased, and no remarkable changes in dosage were observed for other concomitant drugs. These results were favorable in terms of calcium balance. However, there may be limitations in interpreting the results, but the resultant calcium levels suggest that switching to 2.75 mEq/L calcium dialysate may improve the control of calcium levels. In addition, it is hoped that the treatment choice of secondary hyperparathyroidism is extended.

[Hemodoc]

Yes, and when this was tried with nocturnal dialysis, i.e., extended dialysis protocols, the rate of calciphylaxis increased. When they went to 3.0 on the ca in dialysate, the calciphylaxis reversed. You may wish to contact Dr. Brent Miller at Washington University in Saint Louis for his writings on this issue.

[obsidianom]

Yes, and when this was tried with nocturnal dialysis, i.e., extended dialysis protocols, the rate of calciphylaxis increased. When they went to 3.0 on the ca in dialysate, the calciphylaxis reversed. You may wish to contact Dr. Brent Miller at Washington University in Saint Louis for his writings on this issue.

Why do you think this occurs? It seems counter- intuitive that lowering the calcium slightly would cause calciphalaxis. Do you have any theories?

[Hemodoc]

Yes, and when this was tried with nocturnal dialysis, i.e., extended dialysis protocols, the rate of calciphylaxis increased. When they went to 3.0 on the ca in dialysate, the calciphylaxis reversed. You may wish to contact Dr. Brent Miller at Washington University in Saint Louis for his writings on this issue.

Why do you think this occurs? It seems counter- intuitive that lowering the calcium slightly would cause calciphalaxis. Do you have any theories?

http://jasn.asnjournals.org/content/14/9/2322.short

http://onlinelibrary.wiley.com/doi/10.1111/j.1542-4758.2006.00125.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false

http://onlinelibrary.wiley.com/doi/10.1111/j.1542-4758.2007.00172.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false

[obsidianom]

I read several articles on this including the ones you sent and it appears actually there are multiple opinions and in general low calcium in the dialysate is only an issue with nocturnal dialysis due to the long time on the machine . They really made a case for individualizing the calcium to the patient. In my wifes case she would benefit from 2.75  calcium rather than the 3.0 currently in the bath as she runs on the high side. I didnt really see any mention of calciphalaxis.
  I did talk to our nephrologist about sodium levels in the bath just out of interest. They run 140 in center here. He thought 140  made sense with Nxstage.
Why do you think it should be lower ?   Would that work for everyone or just a few patients ?

[Hemodoc]

I read several articles on this including the ones you sent and it appears actually there are multiple opinions and in general low calcium in the dialysate is only an issue with nocturnal dialysis due to the long time on the machine . They really made a case for individualizing the calcium to the patient. In my wifes case she would benefit from 2.75  calcium rather than the 3.0 currently in the bath as she runs on the high side. I didnt really see any mention of calciphalaxis.
  I did talk to our nephrologist about sodium levels in the bath just out of interest. They run 140 in center here. He thought 140  made sense with Nxstage.
Why do you think it should be lower ?   Would that work for everyone or just a few patients ?

Very simply, my plasma sodium level is 135 quite consistently. Every time I have dialysis, I gain a salt load with the 140 mmol. I am afraid your nephrologist has not kept up to date with current recommendations. Every time I go in-center, my current nephrologist runs me at 135 and my post dialysis headaches with in-center disappeared.

As far as the CA issue, this is not a high flow dialysate system. By the law of mass action, with the significantly lower volume, I would not think with 30 liters that a calcium level of 3.0 is going to significantly affect your wife's Ca levels. You may wish to consider other aspects of her mineral bone disease. If her PTH is on the high side, she may be actively depleting her bone minerals and developing osteoporosis. The measured serum Ca is only part of the picture. You may want to determine how much activity she has in her bones since serum levels alone cannot tell you the entire picture. For the majority of patients, the 3.0 is just fine.

[obsidianom]

What is interesting is her calcium runs 10.2 and her phosphorus runs low to low normal without any binders. Her PTH was just checked and is normal at 56 . Her alkaline phosphatase runs very slightly up at 104. Basically all normal with just high normal calcium.

[Hemodoc]

What is interesting is her calcium runs 10.2 and her phosphorus runs low to low normal without any binders. Her PTH was just checked and is normal at 56 . Her alkaline phosphatase runs very slightly up at 104. Basically all normal with just high normal calcium.

That is a very low PTH. The serum Ca level is as you say, high normal. But the PTH in dialysis patients should not ordinarily go below 150 with our secondary hyperparathyroidism from our renal disease. The risk of a low PTH is adynamic bone disease which is a significant risk for fractures. In fact, many now believe 150 is too low as well and believe it is better at a level of around 300. As most things in dialysis, we lack significant studies to show the best practice, but a PTH os 56 sounds too low. You may want to look into that with your medical team.

http://www.sciencedirect.com/science/article/pii/S0272638600742922

[obsidianom]

You are assuming secondary hyperparathyroidism has to occur in renal patients. In my wifes case it doesnt occur. She has always had low normal phosphorus and high normal calcium , even 10 years before kidney failure. So physiologically she is reacting correctly. If the calcium is fairly high, the feedback to the parathyroid will keep it at lower levels . In a manner of speaking she is "normal' in this system.  As long as the calcium is up to high normal levels with normal phosphorus, the system will modulate the parathyroid back down .There is no reason for it to rise.   Our nephrologist was quite impressed with her labs at todays clinic. It is the best she has ever been. Her albumin is up to 4.0 and her hemaglobin was 11.5. Her kt/v with Nxsatge was 3.0 as predicted by the on line calculator.
I did mention your sodium issues to Nxstage in my long phone conferance today. I pushed them to look at it. I dont know if that will help but I tried. I was talking to an upper level managment person. 
While we were at our clinic appt today, in the regular in center upstairs someone crashed as often occurrs on Monday after 2 days off. They took the poor patient to the hospital. The nephro said " that wont happen to you at home" . In other words, we screw up our in center patients but you guys at home do better.    REAL NICE !!   

[Hemodoc]

If your wife does not have secondary hyperparathyroidism, that is QUITE unusual. Have they checked all of the markers for continued PTH responsiveness. That is really not the usual outcome. With renal failure most patients experience the failure of the renal endocrine system to include EPO production and conversion of vitamin D.

Secondly, if her vitamin D conversion is still intact with no need of PTH suppressive therapy, then the Ca level in the dialysate is even less important since the auto-regulatory mechanism is still intact. If that is really true with uremia but endocrine system intact, that truly is quite remarkable. Is she on EPO?

[obsidianom]

Interesting that you mentioned vit d. The nephro actually mentioned he thinks her remaining kidney function may still be processing vit d . We are going to test it by trying some vit d for a few weeks then testing her again to see how this effects her calcium and alk. phos. and phosphorus  etc.
She has always been an enigma to everyone. We still dont know what damaged her kidneys for sure.