I Hate Dialysis Message Board
Dialysis Discussion => Dialysis: General Discussion => Topic started by: Zach on September 03, 2006, 09:02:05 PM
-
Is it difficult for you to keep the same Kt/V each month? Please share your experiences.
How many hours are you on dialysis? How many times a week?
You may be asking, what is the Kt/V?
K stands for the dialyzer clearance, expressed in milliliters per minute (mL/min) You can get this information from your doctor.
t stands for treatment time
Kt, the top part of the fraction, is clearance multiplied by time, representing the volume of fluid completely cleared of urea during a single treatment
V, the bottom part of the fraction, is the volume of water a patient’s body contains
Example: If the dialyzer’s clearance is 300 mL/min and a dialysis session lasts for 180 minutes (3 hours), Kt will be 300 mL/min x 180 min. This equals 54,000 mL, or 54 liters.
Kt = 300mL/min x 180min
Kt = 54,000mL = 54 liters
The body is about 60 percent water by weight. If a patient weighs 70 kilograms (154 lbs), V will be 42 liters.
V = 70 kg x .60 = 42 liters
So the ratio (K x t) to V, or Kt/V, compares the amount of fluid that passes through the dialyzer with the amount of fluid in the patient’s body. The Kt/V for this patient would be 1.3.
Kt/V = 54/42 = 1.3
This information is from:
http://kidney.niddk.nih.gov/kudiseases/pubs/hemodialysisdose/
The National Kidney Foundation (U.S.A.) sponsors the Kidney Disease Outcomes Quality Initiative or KDOQI, which provides evidence-based clinical practice guidelines:
Minimum Delivered Dose of Hemodialysis (Adults Evidence, Children Opinion)
The dialysis care team should deliver a Kt/V of at least 1.2 (single-pool, variable volume) for both adult and pediatric hemdialysis patients. For those using the URR, the delivered dose should be equivalent to a Kt/V of 1.2, ie, an average URR of 65%. However, URR can vary substantially as a function of fluid removal.
Prescribed Dose of Hemodialysis (Opinion)
To prevent the delivered dose of hemodialysis from falling below the recommended minimum dose, the prescribed dose of hemodialysis should be Kt/V 1.3. In terms of URR, a Kt/V of 1.3 corresponds to an average URR of 70%, but the URR corresponding to a Kt/V of 1.3 can vary substantially as a function of ultrafiltration.
Frequency of Measurement of Hemodialysis Adequacy (Opinion)
The delivered dose of hemodialysis should be measured at least once a month in all adult and pediatric hemodialysis patients. The frequency of measurement of the delivered dose of hemodialysis should be increased when:
1. Patients are noncompliant with their hemodialysis prescriptions (missed treatments, late for treatments, early sign-off from hemodialysis treatments, etc.).
2. Frequent problems are noted in delivery of the prescribed dose of hemodialysis (such as variably poor blood flows, or treatment interruptions because of hypotension or angina pectoris).
3. Wide variability in urea kinetic modeling results is observed in the absence of prescription changes.
4. The hemodialysis prescription is modified.
For more information (though a bit more complicated) please visit:
http://www.kidney.org/professionals/kdoqi/guidelines_updates/doqiuphd_ii.html#4
-
1.4
Personally I want it to be higher but the doc says its fine. I would take more time as to me the day is shot anyway.
-
When I was in-center my Kt/V was about 1.2 to 1.3 The doctor always wanted me to run longer but 3 hours was enough for me, I tried 4 hours and I just could not stand it.
On NxStage they measure the Kt/V differently, currently mine .76 but that is daily 5 X week, they say that is VERY good.
-
mine used to be a bit higher but lately it is between 1.4 and 1.7 on average for me.
-
Mine was 1.7 on my last test. But epoman kt/v is kt/v how can they come up with different results? ???
-
Mine was 1.7 on my last test. But epoman kt/v is kt/v how can they come up with different results? ???
Not sure except that it is measured differently than conventional in-center or traditional home-hemo. But I am getting better dialysis now than I was at in-center. My Kt/V is higher.
I need to ask NxStage about that and I will post the technical answer here when I find out.
-
I had my first adequacy test (doing PD- 9 hrs/night) and the nurse mentioned in passing that it the number was 4.1. :o I wanted to ask more but was in a rush to get home and figured I would ask the doctor the next day.... but my appointment got cancelled.
Is 4.1 possible or did I misunderstand? Why is it so high? Should I be happy or worried?
-
If we are talking Kt/V then 1.40 or higher is optimal on Hemo. I'm not sure what numbers are for PD. Maybe you should confirm what you heard and what it was for.
-
Mine was 1.5 and they said it should be 1.8, come on, whats .3 measly little numbers, well, now, they have me on the cycler 11 hours and now i have to have 3000 ml dwelling in me 5 times with one manual drain... crazy huh?
-
oh man, Goofynina. :beer1;
-
I feel sorry for you goofinya, sounds almost like my PD regime. Constantly 9 months pregnant! :-\
I dont think some of the docs here like the kt/v as a way of measuring adequacy. I think Ive had mine done once or twice since Ive been home.
-
I dont think some of the docs here like the kt/v as a way of measuring adequacy. I think Ive had mine done once or twice since Ive been home.
URR is another method. It's easier to understand and figure out mathematically. Here's more:
The reduction in urea as a result of dialysis, or the URR, is one measure of how effectively a dialysis treatment removed waste products from the body. URR stands for urea reduction ratio, but it is commonly expressed as a percentage.
Example: If the initial (predialysis) urea level was 50 mg/dL and the postdialysis urea level was 15 mg/dL, the amount of urea removed is 35 mg/dL.
50 mg/dL - 15 mg/dL = 35 mg/dL
The amount of urea removed (35 mg/dL) is expressed as a percentage of the predialysis urea level (50 mg/dL).
35/50 = 70/100 = 70%
Although no fixed number can be said to represent an adequate dialysis, it has been shown that patients generally live longer and have fewer hospitalizations if the URR is at least 60 percent. For this reason, some groups advising on national standards have recommended a minimum URR of 65 percent.
From the web site:
http://kidney.niddk.nih.gov/kudiseases/pubs/hemodialysisdose/
-
This message was by mistake ... oops! :o
-
Mine can vary by more than .4 from say, 1.3 to 1.75.
Unfortunately there's a bit of room for error in the test, and I wouldn't get yourself in a position of receiving more "tests" to look for problems in your access due to one low Kt/V.
Depending on flow rates during treatment, exact time you're on the machine, and even who draws it, the Kt/V results can really vary.
-
In the UK I have never had how good my dialysis was by Kt/V? We use URR's mine about 63%, the Unit aims for 70 -75% so not a good dialysis that day? Blood is taken at the start of dialysis and at the end of dialysis and both results compared to see how well you are getting dialyized. It gets done once a month so it is on the day?
-
I run about 1.0, which is why I am on hemo 4 times a week and 4 hours at a time. (Had the option of 3 days/5 hours, but I'm climbing the walls after about 2 1/2 hours in the chair as it is. I'd rather take the extra day. They tell me that's probably better for me anyway.) They've tried all sorts of methods to boost it, including using a dual filter arrangement for awhile. For a long time I was about .85-.9, so I have actually improved. For me, going from a fistula to a graft made a difference. They tell me the best thing I could do for my Kt/V is lose weight, and I don't have any trouble believing that. So I battle on.
-
Four treatments a week is real good. I'm glad they gave you that option. :beer1;
-
Oh ya I was gonna post what mine was once I got my results. Average for the month was 1.78 KT/V
Mine was 1.5 and they said it should be 1.8, come on, whats .3 measly little numbers, well, now, they have me on the cycler 11 hours and now i have to have 3000 ml dwelling in me 5 times with one manual drain... crazy huh?
I remember when I was on PD they were telling me that my clearance was barely enough. It seems I do better on Hemo even though I LOVED PD a LOT more :(
-
I would be interested to hear what everyone's URR is. This month mine was 75. In the past it has been 70.
-
Did my URR the other week. Twice actually. On the "normal" dialysis machine I got 78. Then I tested again when I did the HDF machine and the result was 81. Pretty happy with that. So 5 hours, 3 times a week is working for me. :clap; My doctor said to leave it at 5 hours so I do. Liz :beer1;
-
URR is about 90%
-
My average urr since starting dialysis in April has been 72.
-
My URR is 85% on 4hrs 3 x a week. Running at 400 pump speed. I'm happy with that. I do feel a lot better if I go over 85 litres. It seems to be a cut off point for me. Has anyone also noticed a point where they feel a lot better?
-
My URR is 85% on 4hrs 3 x a week. Running at 400 pump speed. I'm happy with that. I do feel a lot better if I go over 85 litres. It seems to be a cut off point for me. Has anyone also noticed a point where they feel a lot better?
What do you mean by "if I go over 85 litres"?
-
I didn't even know about Kt/V, and when you guys started a thread about it, I had to be silent. It is coincidental, but my nurse last Friday told me what mine was. I was telling him that you guys were talking about it and I had no idea. Mine was 1.3
-
I don't know what URR is... what is that?? ???
-
URR is urea reduction ratio which is usually given in percentage. Used to measure if one is getting enough dialysis like Kt/v.
It takes your pre dialysis urea measurement and then subtracts your after dialysis urea measurment. That number is then divided by the pre dialysis measurment and that give you the URR in a percentage.
The reduction in urea as a result of dialysis, or the URR, is one measure of how effectively a dialysis treatment removed waste products from the body. URR stands for urea reduction ratio, but it is commonly expressed as a percentage.
Predialysis urea 75, post dialysis urea 25.
75-25=50
50/75= 66.7%
One should have a URR of greater than 65%.
-
I mean if I have more than 85 litres of blood pumped through the kidney. I'm not sure of the medical term for it.
-
I mean if I have more than 85 litres of blood pumped through the kidney. I'm not sure of the medical term for it.
Now I know what you mean. Thanks.
-
....I wish some of ya'll where my patients....someone actually posted that they want MORE time on the machine. Clearly not one of my patients!
This is an interesting topic. The kt/V has many flaws as a measure of dialysis dose. However, like most of clinical medicine, it is based on the B.A.D. principal.....meaning Best Available Data.
I may have my numbers off a bit, but I think the only study that look at outcomes with different targets was the HEMO study, which overall was a negative study.... I think kt/v of 1.1 was equal to 1.3....or something like this.
The problem(s) start with realizing that kt/V is for UREA clearance. However, urea is not really the "uremic toxin" that makes people ill with kidney failure. The nice thing about urea is that it is cheap to measure, and it is very small. We use it as a marker of the other stuff that builds up with kidney failure that actually would make someone ill. Urea is very rapidly cleared with today's high-flux membranes (F-160, 180, etc...), since it is very small. Most of the clearance of urea takes place in the first hour or two (..."zero order kinetics, for the chemists out there). This is a CONCENTRATION dependent clearance (the higher the concentration, the faster the clearance...thus the first hour is where most of the urea is removed, because your urea is actually higher at the start of the treatment.)
However, we think that many of the toxins in renal failure are bigger than urea....this is the "middle molecule" theory. These bigger molecules (...those into the data might have heard of beta2-macroglobulins as a marker of this size stuff), are not so eaisly cleared. These larger compounds are removed in a more linear (or "first order" kinetics) fashion. In other words, this is more TIME dependent. The amount of these middle molecules removed is THE SAME for each hour of dialysis...the first hr is the same as the last hr. The problem is that we don't measure these things.
So, just by solely focusing on urea modeling (kt/V for urea), we can miss a whole bunch of stuff....so just because your Kt/V is above goal, maybe cutting your time is not a good idea, because you will have less clearance of larger molecules (but we don't measure this). Over time, perhaps this is why ESRD pts have other medical problems faster than other people (vascular disease, etc...).
But, this is hard to study, so a lot of what we do is based on a "belief system"...(like a religion...not proven), rather than on good clinical trials. That is OK, but we just need to remember what our science is based on and what it is not....as to not get too dogmatic over these Kt/V number.
Of course, the government gets involved, and makes these targets that we have to meet to get paid....etc, etc..and weird things start happening that may or may not be based on the "truth", where ever that lies.
Hope I didn't confuse the hell out of everyone. I could go on, but,...as you can guess, they have books written about this stuff (...go figure?..), and there are knock-down, drag out fights during national meetings about this stuff.
-
Thanks Dr Evil,
It is good to know some of the finner points of dialysis.
-
The problem(s) start with realizing that kt/V is for UREA clearance. However, urea is not really the "uremic toxin" that makes people ill with kidney failure. The nice thing about urea is that it is cheap to measure, and is very small. We use it as a marker of the other stuff that builds up with kidney failure that actually would make someone ill. Urea is very rapidly cleared with todays high-flux membranes (F-160, 180, etc...), since it is very small. Most of the clearance of urea takes place in the first hour or two (..."zero order kinetics, for the chemists out there). This is a CONCENTRATION dependent clearance (the higher the concentration, the faster the clearance...thus the first hour is where most of the urea is removed, because your urea is actually higher at the start of the treatment.)
However, we think that many of the toxins in renal failure are bigger than urea....this is the "middle molecule" theory. These bigger molecules (...those into the data might have heard of beta2-macroglobulins as a marker of this size stuff), are not so eaisly cleared. These larger compounds are removed in a more linear (or "first order" kinetics) fashion. In other words, this is more TIME dependent. The amount of these middle molecules removed is THE SAME for each hour of dialysis...the first hr is the same as the last hr. The problem is that we don't measure theses things.
So, just by solely focusing on urea modeling (kt/V for urea), we can miss a whole bunch of stuff....so just because your Kt/V is above goal, maybe cutting your time is not a good idea, because you will have less clearance of larger molecules (but we don't measure this). Over time, perhaps this is why ESRD pts have other medical problems faster than other people (vascular disease, etc...).
Very good post! Thank you for that! :2thumbsup; :thx;
I hope you post more! :clap;
-
If anyone is interested about the next big thing in dialysis, I think it may be Hemodiafiltration (hemodialysis + hemofiltration).
It is used in some countries in Europe. Some data is starting to come out, and it seems promising.
If anyone is interested, post a reply and i will dive into it.
-
....I wish some of ya'll where my patients....someone actually posted that they want MORE time on the machine. Clearly not one of my patients!
I think you may be referring to me. What I meant was I found it easier to endure four days of 4 hour sessions than 3 days of 5 hour sessions. I find 4 hours nearly intolerable some days, but 5 hours would be unbearable. There's another advantage. I don't have to battle the "three day weekend" of fluid control. It's never more than 2 days between sessions for me. I have enough trouble with fluid control without the three day business.
-
Yes- more total dialysis sessions will give you better Kt/V (for urea) than longer sessions less often. This goes back to the concentration-dependent nature of urea clearance... the first hour is the most efficient, so the more "first hours" you have, the better. If it was actually logistically possible, 2 hr treatments 7 days a week would probably work great. The only problem (s) are: Set up time for each treatment; access sticks with fistula; logistical nightmare to try to do this in-center.
If you are home with a catheter and doing home hemo, this can work, but it does take a lot of time.
And, unless you are in some kind of pilot program, there are reimbursement issues...as medicare only pays for a max of 4 treatments a week.
later
-
I would like to know more about hemodialysis and hemofiltration, Dr. Evil.
-
However, we think that many of the toxins in renal failure are bigger than urea....this is the "middle molecule" theory. These bigger molecules (...those into the data might have heard of beta2-macroglobulins as a marker of this size stuff), are not so eaisly cleared. These larger compounds are removed in a more linear (or "first order" kinetics) fashion. In other words, this is more TIME dependent. The amount of these middle molecules removed is THE SAME for each hour of dialysis...the first hr is the same as the last hr. The problem is that we don't measure these things.
So, just by solely focusing on urea modeling (kt/V for urea), we can miss a whole bunch of stuff....so just because your Kt/V is above goal, maybe cutting your time is not a good idea, because you will have less clearance of larger molecules (but we don't measure this). Over time, perhaps this is why ESRD pts have other medical problems faster than other people (vascular disease, etc...).
Is this why 8 hour treatments (nocturnal), six days a week is thought of as one of the better forms of hemodialysis? ... Because it also removes the "middle molecules?"
-
If anyone is interested about the next big thing in dialysis, I think it may be Hemodiafiltration (hemodialysis + hemofiltration).
It is used in some countries in Europe. Some data is starting to come out, and it seems promising.
If anyone is interested, post a reply and i will dive into it.
Yes please do but please create a NEW thread. :thumbup;
-
Is this why 8 hour treatments (nocturnal), six days a week is thought of as one of the better forms of hemodialysis? ... Because it also removes the "middle molecules?"
Yes- you get the benefits of long treatment times (middle molecules) and the frequency of treatments (better urea clearance...ie. Kt/V of urea).
I will start a new thread later on dialysis vs. hemofiltration vs. hemodiafiltration.
EDITED: Fixed quote tag - Goofynina/Moderator
-
So, just by solely focusing on urea modeling (kt/V for urea), we can miss a whole bunch of stuff....so just because your Kt/V is above goal, maybe cutting your time is not a good idea, because you will have less clearance of larger molecules (but we don't measure this). Over time, perhaps this is why ESRD pts have other medical problems faster than other people (vascular disease, etc...).
Since Kt/V is, in part, a function of time, what would you suppose is the minimum (Kt/V) per treatment to remove some of those middle molecules? In other words, does it take at least 3 hours of a single treatment to remove a significant amount of the larger molecules?
And of course, it also depends on the type of filter that is used. ;)
-
I had never heard of Kt/V and URR, but I just calculated them for myself and they are 2,2 and 72% respectively.
pump speed: 360 mL/min
time: 4 hrs (3x a week)
weight (total): 65 kilos
urea before (last monday): 233 mg/dl
urea after: 66 mg/dL
-
I just had blood work again the first wed of the month and got my results on Friday. My kt/V this time is 1.75 while last month it was 1.78
while on the Fresenius 2008K machine it shows the "projected kt/V". It is important to realize that over time you reach the optimum kt/V for the duration you dialyze.
-
So, just by solely focusing on urea modeling (kt/V for urea), we can miss a whole bunch of stuff....so just because your Kt/V is above goal, maybe cutting your time is not a good idea, because you will have less clearance of larger molecules (but we don't measure this). Over time, perhaps this is why ESRD pts have other medical problems faster than other people (vascular disease, etc...).
Since Kt/V is, in part, a function of time, what would you suppose is the minimum (Kt/V) per treatment to remove some of those middle molecules? In other words, does it take at least 3 hours of a single treatment to remove a significant amount of the larger molecules?
And of course, it also depends on the type of filter that is used. ;)
Zach- remember, the Kt/V you are talking about is for Urea. You can pick any marker you want and calculate a Kt/V for it as well. If you get the package insert from the dialyzer (ask your head nurse or Doc), they will have a reference chart for the kidney. Look at the b12 clearance (i think this is about the size of a 'middle molecule'). Anyway, we just don't routinely measure these other molecules in routine care of dialysis patients.
In response to your actual question,.....I don't know how long or how much of the middle molecules are removed in 3 hrs. However, I can say it will be about 25% less than if you were on for 4 hrs (since this is first order clearance, and every hr is the same). The amount of urea you remove that last hr is far less (since the concentration has fallen quite a bit since the first hr). And nobody knows how much is too much or just enough.
This is all about how diffusive clearance works (...or dialysis..... countercurrent osmosis...). If you do hemofiltration rather than dialysis, then you use conventive clearance. This is for the next topic on HD vs hemodiafiltration.....I will get that to that soon. :)
EDITED: Fixed quote tags - Goofynina/Moderator
-
As far as I know I'm on Hemodiafiltration. I look forward to you new thread.
Thanks Alasdair
-
New thread started on Hemodialysis vs. Hemodiafiltration. (Under general discussion)
-
Just to reiterate:
From K/DOQI GUIDELINE 4
Minimum Delivered Dose of Hemodialysis (Adults Evidence, Children Opinion)
The dialysis care team should deliver a Kt/V of at least 1.2 (single-pool, variable volume) for both adult and pediatric hemdialysis patients. For those using the URR, the delivered dose should be equivalent to a Kt/V of 1.2, ie, an average URR of 65%. However, URR can vary substantially as a function of fluid removal.
-
does kt/V vary by the size of the patient for what the goal should be?? (Sorry if this is a dumb question. I am still learning) :-[
-
does kt/V vary by the size of the patient for what the goal should be?? (Sorry if this is a dumb question. I am still learning) :-[
I don't know the full answer to your question, but they tell me one thing holding my Kt/V down is my excessive weight.
-
The V in Kt/V is volume of the patient, so the larger the patient, the longer treatment time is necessary (or better filter) to reach the 1.2 Kt/V.
-
The V in Kt/V is volume of the patient, so the larger the patient, the longer treatment time is necessary (or better filter) to reach the 1.2 Kt/V.
So my being able to reach on average 1.7kt/V is because I am an average sized girl? (I am 165cm / 5'5" @ 63kg / 138lbs (http://www.albireo.ch/bodyconverter/))
-
In fact, some make the argument to drop the V altogether, as we really can't measure the volume with any accuracy in any individual anyway. It is all just a factor of the time and the kidney.
Always remember....the "Kt/V" as we keep using it here, is just for UREA clearance. It is not the be-all, end-all factor that determines the adequate dose of dialysis. You may be doing quite well as a larger person, but can not quite make the exact number the clinic (or medicare) wants.
In fact, larger wt people do better on dialysis, even with lower Kt/V....this holds true across all ages, even adjusting for other illnesses, etc.
-
Why do larger peoiple do better as a whole on dialysis?
-
I don't know mine. I asked on monday and didn't get a responce. So......All I know is it must be good because my time was lowered from 3hr/30mins to 3 hrs. I'm trying to get down to 2hr/45mins now. Less time I have to spend there the happier I'll be. ;D
I'm going to ask again tomorrow and make sure I get an answer.
-
I don't know mine. I asked on monday and didn't get a responce. So......All I know is it must be good because my time was lowered from 3hr/30mins to 3 hrs. I'm trying to get down to 2hr/45mins now. Less time I have to spend there the happier I'll be. ;D
I'm going to ask again tomorrow and make sure I get an answer.
They don't know your kt/V for the day until you are done the 3 hrs. Because it is done over the whole dialysis time. They should have a projected kt/V in the machine though.
-
They don't know your kt/V for the day until you are done the 3 hrs. Because it is done over the whole dialysis time. They should have a projected kt/V in the machine though.
That would be cool, but our machines don't have that display.
EDITED: Fixed Quote tag error - Epoman, Owner/Admin
-
Cool! Mine does look like that - I will check it out tomorrow!
-
Mine doesn't have that display either. The doc was in today to visit. I asked him about my Kt/V. He said it was 1.70.
-
Only Fresenius' 2008K (there are different models/versions .. the hospital's doesn't look like Self Care's) look like that.
If anyone else has a screen that shows it, you should post as well ;) heheh :2thumbsup;
-
My kt/v was 2.1.
I have to find out what my URR is.
-
My kt/v was 2.1.
I have to find out what my URR is.
Ohio Buckeye, that's a great Kt/V!
-
My KT/V is getting worse. This time it was 1.13. I'll look into what dialyzer I'm on. I sure don't want to dialyze longer.
-
Is the nocturnal dialysis still an option for you rerun? It would certainly improve your kt/v a great deal.
-
My KT/V is getting worse. This time it was 1.13. I'll look into what dialyzer I'm on. I sure don't want to dialyze longer.
You might also check to see what dialysate flow rate they are running you at and if it could be increased also.
-
my kt/v for november was 2.40... however, my creatnine for Nov was 12.1, up from 9.0... so im hoping it goes down next month, or else there going to be adjusting my prescription again :banghead;
-
Is the nocturnal dialysis still an option for you rerun? It would certainly improve your kt/v a great deal.
If I would sell my house then I could move up to Spokane where the Nocturnal is available.