In the infancy of dialysis, the quality of water used during the treatment was not a focus of concern. The innovative pioneers were acutely aware of a variety of problems such as clotting, air in the extracorporeal system, appropriate membranes, access, improvising equipment for performing dialysis, and so many other unforeseen challenges.
It is now well known that many of the chemical substances in municipal water are potentially dangerous for dialysis patients, some of which (calcium, sodium, aluminum, chloramines, fluoride, copper, zinc, sulfates, nitrates) are able to illicit well-defined acute or chronic poisoning syndromes (see Table 1).
Risk of contamination is high
Water is one of the best known solvents. It is of this property that water can so easily be contaminated. Some of these contaminants, such as mineral salts, suspended particles (sand and clay) and products of organic origin (lignin, tannin), may be naturally present in the hydric reserves. Others such as copper, zinc and lead, may be released by the pipes forming the water distribution system. Also, human activity can introduce its share of contaminants such as fertilizers, pesticides, nitrates, hydrocarbons, fluoride, halogen, and municipal dumps.
The dialysis process can also contribute to unwanted contamination that can affect the safety and well-being of the patient. Improper design and poor maintenance of the dialysis water system can introduce chemicals and produce bacterial and endotoxin in the water purification and distribution system (see Table 2).
The quality of the water originating from a municipal supply is stringently regulated. Within the United States, under the Safe Drinking Water Act (SDWA), the Environmental Protection Agency (EPA) sets legal limits on the levels of contaminants in drinking water. The limits are based upon known toxicity of individual contaminants and upon technology available to remove the contaminants.
But what is safe for drinking is not necessarily safe for use in dialysis. In a typical 45X formulation-based proportioning, approximately 94% of the dialysis fluid is water, approximately 4% is sodium bicarbonate portion, and approximately 2% is the acid portion.
Water is the largest proportion of the prescriptive dialysis fluid, yet it is never listed in an order set or physician’s order as part of the dialysate prescription. As part of the compound of the prescription, water is no longer just water but is the predominant compound of the prescription. In essence, it is the highest volume of “medication.” The focus is on the potassium, calcium, sodium, and bicarbonate concentration.
A syringe filled with a wrong concentration or a wrong medication and administered either by infusion or via intramuscular route can harm and potentially kill a patient.
Similarly, exposing the dialysis patient to incorrect dialysis electrolyte concentration can have similar outcome. Patients can also be exposed to water contaminant contribution, such as chloramine, calcium, disinfectant, bacteria and endotoxin which, albeit with the interposition of a semi-permeable membrane, come into direct contact with the bloodstream. In essence, it becomes another means of parenteral administration with the water system as a pseudo syringe. Shouldn’t this “largest syringe” used in dialysis be treated with the due respect of its high exposure volume to the patient?
AAMI and water standards
The Conditions of Coverage issued by the Centers for Medicare & Medicaid Services for dialysis facilities includes references to AAMI (Association for the Advancement of Medical Instrumentation) recommended practice RD52:2004 Dialysate for hemodialysis and standard RD62:2001 (see Figure 1).
The water treatment equipment for hemodialysis applications states, “The medical director is ultimately responsible for the safety and quality of the water used for patient treatment.” The regulation further states that, “The medical director must be knowledgeable of the water treatment system installed and assure that the system as installed will produce AAMI quality water.”
It is not expected that the physician in charge is the facility expert on water treatment. It is, however, expected that the physician possesses the key knowledge and factors that ensure that patients are receiving the highest quality of dialysis water and not adversely affected by improperly treated water.
Important steps to delivering clean water for dialysis
Dialysis water treatment employs various levels of pre-treatment, a final purification module (typically a reverse osmosis) and a means of distributing the purified water to the point of use. The technological sophistication of modern dialysis can produce water of optimal chemical and microbial quality.
However, there is no single type of purification treatment capable of delivering chemically and bacteriologically pure water in a perpetual way due to the variations of municipal water geographical variations, maintenance of the water system, level of knowledge with regulatory standards, skill and competency of individuals involved in water treatment, and design of the water system.
The risk of chemical contamination to the water is due mainly to the primary pollution of municipal water. The level and types of contaminant delivered to the facility will determine the types of components necessary to incorporate into the design of the water system so that AAMI quality water can be produced and maintained.
The result of a pre-design water analysis must be reviewed and the decision to accept and authorize a water purification system design must be reached with assistance from knowledgeable individuals with operational and regulatory understanding of components and processes to address the specific contaminants evidenced by the water analysis. The key in the collaborative decision is to ensure the installation of a system that can deliver dialysis water that is safe and high purity.
A secondary means of chemical contamination can be as a result of the facility actions.
- Improper rinsing of chemicals used for water system disinfection can expose patients to harmful agents.
- Improper testing for total chlorine can expose patients to chloramine that can induce hemolysis.
- Improper use of materials in the purification and distribution system can leach harmful compounds into the dialysis water.
The importance of maintenance
A system designed right is only effective if it is maintained right. It is paramount that those responsible for maintaining the water system do so without deviation from established policies and procedure and that the physician is aware of all activities, detrimental or beneficial. All water issues should be an integral part of the Quality Assurance and Performance Improvement program.
The other water concern that requires physician engagement is bacterial contaminant in the purified water. As stated in the AAMI guidelines, “Product water used to prepare dialysate or concentrates from powder at a dialysis facility, or to process dialyzers for reuse, shall contain a total viable microbial count lower than 200 CFU/ml and an endotoxin concentration lower than 2 EU/mL. The action level for the total viable microbial count in the product water shall be 50 CFU.mL, and the action level for the endotoxin concentration shall be 1 EU/mL. If those action levels are observed in the product water, corrective measures shall promptly be taken to reduce the levels.”
Delivering quality water for dialysis
The water produced by reverse osmosis has an optimal microbial quality; the challenge is how to maintain this level of quality. Because the purified water no longer contain the municipal disinfectant, the large surface area of the distribution system (storage tank, piping loop, pump heads, filter housing, dialysis machine water line) can be a conducive environment for microbial growth. The technological advancement and sophistication allows for the production of high purity water, but it is the techniques and practices that are often underestimated that can potential jeopardize the dialysis patient.
Microbial contamination of the dialysis fluid can cause acute intradialytic complications (pyrogenic reactions, cardiovascular instability, headache, nausea, cramps) and, by maintaining a state of chronic micro-inflammation, it may be involved in the pathogenesis of a number of chronic complications typical of the uremic state, such as amyloidosis, atherosclerosis and malnutrition.
The production of highly purified water can easily be achieved with available technological sophistication and advancement. The responsibility and challenge faced by the physician and the facility is to maintain the level of quality produced by the appropriately designed water purification system.
Maintaining a properly designed system is only achievable with the understanding and knowledge of standards and recommended practices, regulations and water system applications. Applying the same attitude with water as to the potential administration of a wrong medication can lead to a higher respect for the production and maintenance of the quality of dialysis water.