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Part One


There are two main dialysis options




This dialysis option is the focus of this website and will be discussed hereafter in detail


But first …


Peritoneal Dialysis


Please Note … although this website does not discuss peritoneal dialysis in any detail, it is an excellent dialysis choice for many patients.


In our own program, 20-25% of our patients use peritoneal dialysis. Of these, a little over half now use overnight, automated peritoneal dialysis.


Peritoneal dialysis, though NOT the focus of this website, is both a home therapy and, at least potentially for most, an overnight one too.


You should discuss the peritoneal dialysis options with your dialysis unit.


Further useful information on it can be found at:



Or, to learn about overnight home peritoneal dialysis (APD), try…



From now on, however, the focus of this website is entirely on haemodialysis.


This is not intended to represent bias – it simply means that this site is intent on one task alone – to explain the processes of haemodialysis and to introduce you to nocturnal home haemodialysis.




There are several haemodialysis options. It is important to note that the terminology that is used will vary a little - country to country


Choices also depend upon both availability and geography


… That having been said, the three main choices are:


Centre-based haemodialysis


Limited care ‘satellite’ haemodialysis


Home-based haemodialysis


For most patients on dialysis, haemodialysis has, by ‘convention’, always been: 4 hours, 3 times/week (or some near variant). From here on at this website, this will be called ‘4x3 HD’


Worldwide, dialysis time per session varies significantly


The average sessional duration in the US is still less than 4 hours and closer to 3 ½ hours.


In other countries and regions, sessional duration is more commonly in excess of 4 hours and in Australia, closer to 4 ½ hours while Japan is closer to 5 hours.


Individual facility-based treatment duration is rarely greater than 5 hours


Worldwide, dialysis is routinely prescribed only three times per week and thus forces a ‘long break’ on all facility-based patients doing conventional 3x4 HD


BUT … have you ever asked yourself – WHY?


There are three important questions


1. Is haemodialysis practice based on good science?


2. Are there smarter, newer technologies around?


3. Might newer approaches produce better outcomes for patients?


And … there is a fourth and important question – at least, it is a key question for governments and funding agencies …


4. Can better dialysis be delivered yet at lower cost to the provider (i.e. governments and taxpayers)?


When kidneys fail


They almost always fail permanently and fail in all their functions …

            Little or diminishing waste excretion occurs

            Little or diminishing fluid excretion occurs

            Little or diminishing ‘other functions’ occur


This means that all (or most) wastes ‘stay on board’ and all (or most) fluid swallowed stays inside the body which inevitably …

            Swells the blood volume

            Raises the blood pressure

            Stretches the heart and blood vessels




So … how do we replace the functions of this usually continuingly functioning ‘vital’ organ?




At the moment, we use artificial kidney treatment (standard, conventional dialysis) for an average total of 12 hours out of the 168 hr week


                … or 7% of the time


This is to replace the function of an organ system used to running, in the background, 24 hours a day, 7 days a week


               … or 100% of the time




Is this enough?




Standard dialysis practice - (4x3 HD)


Is currently performed, in most places round the world, for 4-5 hrs dialysis on Mon/Wed/Fri or Tues/Thurs/Sat … with Sundays off!


This means that …


In 4-5 hrs, all wastes and fluids gained must be removed


This results in a 2nd/3rd daily ‘assault’ on body biochemistry and blood volume


No wonder so many on 4x3 HD feel like they have been run over by a steamroller every other day


So … what governs good dialysis?


Dialyser surface area (m2)

Blood flow rate (pump speed)

Dialysate flow rate


… these factors are easy and popular to adjust … but are relatively ineffective


Dialysis Time

Dialysis Frequency


… these factors are also easy but unpopular to adjust … but are very effective



In my view … ‘optimal’ dialysis should be …


24 hrs/day, 7 days/wk – just as a pair of normal kidneys would provide - but no-one wants to depend on a machine like that!


Humans must live, react, inter-act, work, play, love, laugh, weep, enjoy, thrill … all in their waking hours


Yet, currently, we hook our patients up to dialysis machines in their waking hours, just when they should be doing their ‘living’ things


So, it stands to reason that optimal dialysis can only be provided for long and often enough if it is provided during sleep, and thus ensuring optimal ‘living time’


… But how?


Let us think about ‘time’ and ‘frequency’


The Key Question


If better dialysis means increasing time, frequency or, best of all, both … is there a way to do that that is not lifestyle-intrusive?




Daytime dialysis time beyond 4-5 hrs is ‘unacceptably intrusive’ for most patients so … the only viable way to increase dialysis time is to perform dialysis during body ‘down-time’ … i.e. during sleep


Haemodialysis while asleep has long been ‘off-limits’, but … improvements in technology with more creative thinking and solutions to the instability of blood pressure … have made night-time dialysis safe


            ... see  SAFETY ON NHHD and DIALYSIS ISSUES




Daytime dialysis frequency beyond 3-4 treatments/wk is also ‘unacceptably intrusive’ for many patients so, the best way to increase frequency is to dialyse more often.


This can be done either …


            by shortening the duration of each dialysis … i.e. short (2hr), daily (6days/wk) dialysis (6x2 HD)


            by doing dialysis at night, while asleep, so that the higher frequency of dialysis sessions is masked by being done during sleep


With short, daily dialysis, dialysis exposure/wk is the same as for conventional 3x4 HD - it just turns the 4x3 = 12 hrs into 6x2 = 12 hrs


Short, daily HD (6x2) has both advantages and disadvantages


            As dialysis efficiency is maximal at the start of dialysis, 6x2 HD is more efficient than 4x3


            But ..


            Greater travel time to and from the dialysis centre limits the appeal of short, daily HD unless it, too, is done at home


Time and Frequency


Increasing daytime frequency and time makes during-the-day dialysis totally impractical but … using the night and dialysing while asleep is the clear and only practical way to increase both time and frequency



This use of ‘nocturnal’ or ‘overnight’ time

is now possible and safe

due to better equipment and safety options




Nocturnal haemodialysis (NHHD) is both safe and practical yet leaves the waking hours undisturbed 


Increasing time and frequency raises dialysis efficiency. Doubling both the number of treatments/wk from 3 to 6 and the duration of each treatment/wk from 4 to 8 increases the efficiency of waste/fluid removal 4 fold


This 4 fold increase in efficiency allows:

                The blood flow rate (pump speed) to be reduced     

                The dialysis fluid flow rate to be slowed right down

                Dialysis becomes almost ‘subliminal’


And … the circulation sighs a heart-felt ‘thank you’


The following graphs show the effect that increasing the duration and/or frequency of dialysis has on the build-up and removal of fluid and wastes.


I have used S.Creatinine measured in mmol/l (SI units) as the ‘y’ (or vertical) axis … but it could represent any waste (or fluid volume) which accumulates and then requires removal during dialysis 

Schematic diagram (4hrs x 3/wk) = Conventional (4x3) Haemodialysis

Waste levels and blood volume fall rapidly over each 4 hr HD (represented    by the red bars) then rise again over 44 hrs (midweek) or over 68 hrs (weekend) … the cycle recurring the next week

Schematic diagram (2hrs x 6/wk) = Daily (short hour) Haemodialysis

Waste levels and blood volume fall rapidly over each 2 hr HD (represented    by the red bars) then rise again over 22 hrs (midweek) or over 46 hrs (weekend) … the cycle recurring the next week

(continued in the next ‘Part’)


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Authored by Prof John Agar. Copyright © 2012
Nocturnal Haemodialysis Program, Barwon Health.
All rights reserved. Revised: July 1st 2012