This AAMI 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. In 2008, CMS adopted this document as a standard of practice for the United States ESRD program.
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 ultrapure 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 below:
RD52 Data Supporting Higher Dialysate Quality
RD52 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 dialysate
200 CFU/ml
Action limit of 50 CFU/ml
2 EU/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 rationale 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 units.
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 EPO
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 filter.
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 ultrapure dialysate. This would mean that large capital investments would have to be made for something that as yet was not conclusive. At that time 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 (see latest ANSI/AAMI Standards). Thus, if any changes are made to a facilities water system, consideration should be given to meeting requirements for ultrapure dialysate and water.
RD52 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.
This Standard is a recommended practice and as such is addressed to the user and the requirements that are the user’s 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 considered RD62 “Water treatment equipment for hemodialysis applications” the manufacturers requirements and RD52 the users requirements. Parts of both RD52 and RD62 are the same as it relates to water.
RD52 addresses many more aspects of the dialysate fluid system other than just water treatment. The concentrates are covered along with dialysis machine disinfection including the total system; from where the potable water enters the water purification system to where the dialysate enters the dialyzer. 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. Conventional dialysate is required, but ultrapure dialysate is highly desirable. 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, 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 hints 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 meaning 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.
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. RD52 has some general discussion on this type of concentrate system that should be followed.
In Chapter 6 of RD52 there is a Quality Control chart that recommends what general testing should be completed and at what intervals. This chart can be used by the facility to help design a quality system to confirm performance testing. 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 current use.
As RD52 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 rationale used by the committee to make their decision on certain subjects. Many times this rationale can be used by the reader to understand why the requirements were specified. There is also a large reference list for anyone needing additional information.
Addendums were further added in 2009 that include Annex E: Special considerations for acute hemodialysis along with an update to Annex C: Special considerations for home hemodialysis, C.5.C Deionization.