AAMI’s Dialysate for Hemodialysis has now been
released and is available from AAMI. This document gives recommendations
for the entire fluid system from the pretreatment of water to the
final dialysate production. All aspects of the system are discussed
in detail. Although it is not clear whether CMS will adopt this
document as they have others in the past, it is clear that this
will become a standard of practice for the United States.
The main purpose for developing this recommended
practice is because evidence is now showing that as the level of
endotoxin in the dialysate goes up, the mortality rate for dialysis
patients also increases. The use of ultra pure dialysate has shown
to reduce the mortality rate in several European studies. Elevated
levels of pyrogens in the dialysate are known to activate C-reactive
proteins, which are an indicator of potential heart failure. Endotoxin
is also known to cause inflammatory responses. Even though these
studies are not as yet conclusive by limiting the allowable level
of endotoxin in the dialysate, the patient should be better served.
Some of the reference studies used to make this decision are listed
RD-52 Data Supporting Higher
RD-52 recommends that the dialysate be tested for
bacteria and endotoxin monthly, similar to the water recommendation.
The level of bacteria and endotoxin that should be met is the
same as that of the water system.
AAMI bacteria and endotoxin recommendations for
Action limit of 50 CFU/ml
Action limit of 1 EU/ml
The AAMI committee felt that these limits were reasonable
and obtainable by most facilities in the United States. However,
the committee stresses the need to try and do better than this.
The committee emphasizes that in the future the levels of allowable
endotoxin are likely to be lowered. The justification for lowering
the levels will be new scientific data that is being brought forward
from new studies.
During the review of this recommended practice
the AAMI committee considered the data that was currently available.
To help you better understand the rational behind AAMI reasoning
to lower the limits. Below are listed papers that will help educate
you on why better quality dialysate should be a priority in dialysis
Decrease in Serum R2-microglobulin
Indirect evidence increasingly shows that chronic
exposure to low amounts of endotoxin may play a role in some of
the long-term complications of hemodialysis therapy. Patients
treated with ultrafiltered dialysate have demonstrated a decrease
in serum R 2-microglobulin concentrations as shown in the next
paper "Methods of hemodialysis." This paper is
in German with only the abstract is in English.
Decrease in Inflammatory markers
The next paper, "The effect of ultrafiltered
dialysate on the cellular content of interleukin-1 receptor antagonist
in patients on chronic hemodialysis" demonstrated a decrease
in the marker of inflammation IL-IRa when patients are treated
with high quality dialysate.
Thomas Sitter's paper "Dialysate
related cytokine induction and response to recombinant human erythropoietin
in haemodialysis patients" showed elevated CRP and IL-6
with standard dialysate and a significant decrease when ultrapure
dialysate was used.
The next paper "Effects of ultrapure
dialysis fluid on nutritional status and inflammatory parameters"
also showed a significant reduction in CRP and IL-6 when ultrapure
dialysate was used to treat patients. He also showed a significant
increase in estimated body weight and muscle mass over the 12
months of the study.
Increase in the responsiveness of
This paper "Chronic inflammation
and water quality in hemodialysis patients" concludes
that water systems in dialysis units should be given careful design
and rigorous monitoring. By doing this inflammation markers can
be reduced and EPO therapy enhanced.
The next paper "Endotoxin-free dialysate
improves response to erythropoietin in hemodialysis patients"
showed a marked decrease in the amount of EPO needed when switched
to ultrapure dialysate.
Association with ß-2 microglobulin-amyloidosis
The next paper "Using ultrapure water
in hemodialysis delays carpal tunnel syndrome" showed
a reduction in Carpal Tunnel Syndrome (CTS) when ultrapure dialysate
was used. He said that this may be due to less stimulation of
monocytes resulting from the absence of bacteria, endotoxins and
pyrogens in the dialysate.
In the paper "Clinical manifestations
of AB-amyloidosis: Effects of biocompatibility and flux"
Schiffl showed that the lower the contamination level in the dialysate
the lower clinical symptoms of AB-amyloidosis in the patients.
Preservation of renal function
The next paper "Identical decline
of residual renal function in high-flux biocompatible hemodialysis
and CAPD" indicated that the use of ultrapure dialysate
reduced the rate of residual renal function.
Schiffl's study "Ultrapure dialysis
fluid slows loss of residual renal function in new dialysis patients"
showed that the use of ultrapure dialysate lowered CRP and IL-6
and the rate at which a patient lost residual kidney function.
In his study, the normal dialysate contained up to 300 CFU/ml
and the ultrapure dialysate was filtered through a >22 micron
The quandary that AAMI faced in developing
the dialysate recommended practice was that many water and dialysate
systems in the United States were not able to meet the levels of
ultra pure dialysate. This would mean that large capital investments
would have to be made for something that as yet was not conclusive.
AAMI decided to take an interim step and require that the dialysate
meet the same level as the water for dialysis (200 CFU/ml and 2
EU/ml) with recommendations that lower levels are better. AAMI also
stated that it would review this recommended practice and most likely
lower the limit in the future. Thus, if any changes are made to
a facilities water system, consideration should be given to meeting
requirements for ultra pure dialysate and water.
RD-52 also covers all aspects of the fluid
system from the mixing of powdered bicarbonate concentrates to the
disinfecting and maintenance of the distribution system. This recommended
practice is a must for dialysis units.
RD-52 is a recommended practice and as such
is addressed to the user and the requirements that are the users
responsibility once a system is installed. It is not possible to
hold a manufacturer responsible for meeting requirements that require
the user to maintain. Thus the AAMI committee considers RD-62 “Water
treatment devices for dialysis” the manufacturers requirements
and RD-52 the users requirements. Parts of both RD-52 and RD-62
are the same or will be changed to be the same when the committee
makes the next revisions to RD-62, which is currently underway.
RD-52 does address many more aspects of the
dialysate fluid system than just the water treatment. The concentrates
are addressed along with the dialysis machine disinfection. The
total system from where the potable water enters the water purification
system to where the dialysate enters the dialyzer. As one can see
from above, the critical factor is the purity of the dialysate.
Since water is such a large portion on the dialysate it is important
to keep the water as pure as possible.
In RD52 there are three levels for dialysate.
Conventional dialysate, ultrapure dialysate and dialysate for infusion.
At this time conventional dialysate is required but ultrapure dialysate
is desired. In the future it is anticipated that the FDA will approve
the use of Hemofiltration and Hemodiafiltration dialysis equipment
that prepare replacement fluids on line. When this occurs the dialysis
systems will need to be able to prepare dialysate for infusion.
Since this fluid is being infused directly into the blood stream
dialysate for infusion needs to be sterile and meet the requirements
of dialysate for infusion.
Descriptions of the Equipment used to purify
water are included along with helpful hint on how they should be
used. There is nothing revolutionary about these description but
they can be helpful for training and review.
Water distribution systems are discussed in
another section. These systems are particularly vulnerable to bacterial
contamination because the chlorine and chloramines have been removed
from the water that flows through the distribution system and the
distribution loop needs to be disinfected regularly. The materials
of construction for distribution loops and methods of disinfection
are also discussed in some detail.
Recently some manufacturers have begun offering
powdered concentrates. This is where a user buys pre-measured powders
from a supplier and adds pure water at the dialysis facility to
make concentrate. These systems are designed to reduce the cost
of concentrate but must be monitored and watched carefully to prevent
contamination or misuse. RD-52 has some general discussion on this
type of concentrate system that should be followed.
In Chapter 6 of RD-52 there is a Quality Control
chart that recommends what general testing should be preformed and
at what intervals. This chart can be used by the facility to help
design a quality system to confirm what testing needs to be performed.
It is noted that this chart will need to be customized for the facilities
own requirements due to the large variation in water systems in
As RD -52 is being read it is important to
remember that the committee has included Annex A at the back of
the document which gives some of the rational used by the committee
to make their decision on certain subjects. Many times this rational
can be used by the reader to understand why the requirements were
specified as they were. There is also a large reference list for
anyone needing additional information.