Dialysis Water: Monitoring the quality for hemodialysis and dialysis fluids

Dialysis water is one of the vital component for patient care. There is no denying the fact that drinking water allows the liquid to be processed through the gut and liver, where contaminants are inactivated or removed before absorption into the blood. But when it comes to dialysis water/dialysis fluid, water comes in direct contact with patient’s blood instead of the gut. This impeccably defines the difference and significance of dialysis fluid simultaneously.

To keep dialysis water quality intact, recommendations and international standards are available for the guidance of maximum allowable concentration of contaminants.

Maximum allowable concentration of Microbial Contaminants:

The presence of microbial contamination contributes to the development of biofilm, which in later stage is difficult to remove and results in the release of bacteria and bacterial fragments. These fragments in turn pose serious threat to the patient’s health if appropriate measures are not actualized.

Hence, the maximum allowable concentration as per standard requirements for dialysis water is less than 100 CFU/ml and for Endotoxin it’s less than 0.25 EU/ml. It’s pertinent to mention here that Endotoxins are the major component of outer cell wall of bacteria that are capable of causing severe infection, may lead to organ failure and even death if suitable measures are not taken.

The frequency of microbial testing:

Contaminant	Frequency	Maximum recommended concentration
Microbial Count	Monthly	<100 CFU/ml ( Action Level > 50 CFU/ml)
Endotoxins		0.25 EU/ml ( Action Level 0.125 EU/ml)

BS EN ISO 23500:2015 states there is no requirement to test for bacterial growth or endotoxins when the hemodialysis system is fitted with endotoxin retentive filters that are operated according to the manufacturer’s instructions, unless the manufacturer requires such tests to be performed.

Maximum allowable concentration of Chemical Contaminants:

Various chemicals have been clearly shown to be toxic to dialysis patients at concentrations that are not necessarily toxic to the general population. Those chemicals include aluminum, copper, chloramines, fluoride, nitrate, sulfate, and zinc. Organic chemicals have not been identified as toxic to hemodialysis patients because they are removed through reverse osmosis and carbon adsorption.

Following is the list of maximum allowable concentrations of chemical contaminants in dialysis water for which monitoring is mandatory:

Chemical Contaminant	Maximum recommended concentration (mg/l=ppm)
Aluminium	0.01
Calcium	2 (0.05mmol/l)
Copper	0.1
Fluoride	0.2
Magnesium	4 (0.15mmol/l)
Nitrate (as N)	2 (equates to 9 mg/l NO3
Potassium	8 (0.2mmol/l
Sodium	70 (3.0mmol/l
All of the above chemical contaminants when indicated should be tested initially every 3 months and are mandatory for the monitoring.
Arsenic	0.005
Cadmium	0.001
Chromium	0.014
Lead	0.005
Mercury	0.0002
Sulphate	100
Above group of contaminants for which the drinking water limit is 2 to 5 times the recommended limit for dialysis. In water treated by reverse osmosis, these contaminants will only exceed the limits if they occur at relatively high levels in the water supplied to the unit. These contaminants can be omitted from routine tests if data is available to show that the levels in the water supplied to the unit rarely exceed the limit. Such data is generally reviewed on an annual basis.
Barium	0.1
Beryllium	0.0004
Silver	0.005
Thallium	0.002
Zinc	0.1
The final group of contaminants (barium, beryllium, silver, thallium, tin and zinc) of trace elements are not considered to occur in levels that give cause for concern and, if low levels are present, they are removed effectively by reverse osmosis. Testing is only required if there is evidence of high levels in the local water supply (zinc, for example, can be introduced in the pipework or silver, present if the hospital water supply is treated with silver containing compounds to minimize the presence of Legionella bacteria).  If testing for trace elements is not available, compliance may be demonstrated by compliance with standards for potable water as defined by the WHO or local regulations. If neither of these options is available, compliance can be met through a reverse osmosis system with a rejection of >90 % based on conductivity, resistivity, or TDS.

 References

1. BS EN ISO 13959; 2015:Water for haemodialysis and related therapies

2.European Pharmacopoeia, 8 th ed. Monograph 1167:Haemodialysis solutions, concentrates, water for diluting. European Pharmacopoeia Commission 2014

3. Poli D, Pavone L, Tansinda P, Goldoni M, Tagliavini D, David S, Mutti A, FranchiniI. Organic contamination in dialysis water: trichloroethylene as a model compound. Nephrol Dial Transplant 2006 Jun; 21(6):1618-1625

4. The Water Supply (Water Quality) (England and Wales) Regulations 2000.Statutory Instrument No. 3184.Prescribed concentrations and values .http://www.dwi.gov.uk/regs/si3184/3184.htm#sch1 and http://dwi.defra.gov.uk/stakeholders/legislation/wqregs2007cons.pdf.

5. BS EN ISO 26722; 2015:Water treatment equipment for haemodialysis and related therapies

6. BS EN ISO 23500; 2015: Guidance for the preparation and quality management of fluids for haemodialysis and related therapies

7. JCI 7th Edition