Dialysis is a life-sustaining medical procedure for individuals whose kidneys can no longer effectively filter waste products and excess fluid from their blood. It diverts a patient’s blood to an external machine (dialyzer) for thorough cleaning before returning it to the body. This treatment becomes necessary when kidney function declines, causing harmful substances to accumulate and pose severe health risks.
Dialysis and the Role of Water
Water plays a central role in dialysis, specifically in creating dialysate, the fluid that cleanses blood. Dialysate is primarily purified water mixed with electrolytes and minerals. During hemodialysis, blood flows through a dialyzer, separated from dialysate by a semi-permeable membrane. This membrane allows waste products and excess fluid to pass from blood into dialysate, while beneficial components remain. Due to this direct and extensive contact, water quality is critical.
Patients are exposed to significant water volumes, typically 300-600 liters per week (120-200 liters per session). This exposure highlights why dialysis water purity standards far exceed those for drinking water. Unlike drinking water, where the body’s digestive system and liver neutralize contaminants, dialysis allows impurities to directly enter the bloodstream, bypassing protective barriers and causing immediate or long-term health complications.
Common Water Impurities and Their Dangers
Tap water, while safe for drinking, contains impurities that pose threats if present in dialysis water. Common chemical contaminants in municipal water include chloramines and chlorine, used for disinfection. If these enter the bloodstream during dialysis, they can damage red blood cells, potentially leading to hemolytic anemia.
Heavy metals such as aluminum, copper, and lead can be present, often leaching from plumbing or existing in source water. Aluminum, for instance, is sometimes added to municipal water as a flocculating agent. These metals can accumulate in a dialysis patient’s body, as impaired kidneys cannot effectively remove them.
Other chemical impurities like fluoride, calcium, magnesium, nitrates, and sulfates, while harmless in drinking water, can become toxic in dialysis. Fluoride, for example, can contribute to bone abnormalities, and excessive calcium or magnesium can disrupt the body’s electrolyte balance. Microbiological contaminants, including bacteria, viruses, and their byproducts like endotoxins, are a significant concern.
These microorganisms or their fragments can easily pass through the dialyzer membrane into the patient’s blood, triggering infections, fever reactions, or systemic inflammatory responses. Biofilms, communities of microorganisms, can also form within the water distribution system, acting as persistent sources of contamination.
Health Impacts of Contaminated Dialysis Water
Exposure to contaminated water during dialysis can lead to various physiological consequences for patients. Anemia, a common issue in kidney disease, can be exacerbated by impurities such as chloramines, which damage red blood cells, or by aluminum, which can suppress red blood cell production. Patients may develop bone disease, specifically osteomalacia, as aluminum and fluoride can interfere with normal bone metabolism and lead to bone pain and non-healing fractures.
Neurological issues, including cognitive impairments and a condition historically known as “dialysis dementia,” have been linked to the accumulation of heavy metals, particularly aluminum, in the brain. Contamination by bacteria and endotoxins can provoke acute inflammatory responses, characterized by fever, chills, and a general feeling of illness.
Beyond immediate reactions, chronic exposure to endotoxins and other microbial components can lead to a persistent state of low-grade inflammation in the body. This chronic inflammation contributes to cardiovascular problems, which are a leading cause of death among dialysis patients. Other toxic substances, if present, can accumulate and damage multiple organ systems, further compromising the health of dialysis patients.
The Purpose of Water Treatment in Dialysis
Water treatment for dialysis goes beyond providing “clean” water; it aims for an ultra-pure standard to prevent health issues from impurities. The purification process removes specific ions, trace elements, bacteria, and endotoxins to levels far below drinking water standards.
This is accomplished through multi-stage treatment methods, which typically include pre-filtration, activated carbon filtration to remove chlorine and chloramines, water softening to reduce mineral hardness, and the primary purification steps of reverse osmosis and deionization. Reverse osmosis effectively removes the majority of dissolved solids, bacteria, and endotoxins, while deionization further removes ionic contaminants.
These rigorous standards are established and enforced by organizations such as the Association for the Advancement of Medical Instrumentation (AAMI). AAMI guidelines specify strict limits for chemical contaminants and significantly low levels for microbial counts and endotoxins, for example, less than 100 colony-forming units (CFU) of bacteria per milliliter and less than 0.25 endotoxin units (EU) per milliliter.
Adherence to these stringent requirements is essential because dialysis patients are uniquely vulnerable to waterborne contaminants. Achieving this high level of purity ensures the safety and effectiveness of the dialysis treatment, directly contributing to improved patient outcomes and reducing the risk of life-threatening complications.