This latest AAMI Standard (a revision of RD62) provides guidance for water requirements used in hemodialysis and related therapies. It includes any water used to prepare concentrates, the make-up of dialysate, hemodiafiltration and hemofiltration, and the practice of reprocessing dialyzers. This Standard only details water quality and does not provide specific guidance on water treatment equipment.
Water quality for dialysis must be verified at the time the water system is installed and then continually monitored. Methods used to determine water quality are established by examining the microbiological requirements. These have been established as Colony Forming Units, or microbial counts, and Endotoxin Units. The latest AAMI standards are as follows:
|Microbiological Level||Water Standard||Water Action Level|
|Colony Forming Units||< 100 CFU/mL||≥ 50 CFU/mL|
|Endotoxin Units||< 0.25 EU/mL||≥0.125 EU/mL|
As part of water quality, this Standard provides a US deviation to ISO 13959:2014. In regards to compliance testing with microbiological requirements, the latest ISO Standards read: “Culture media shall be tryptone glucose extract agar (TGEA) or Reasoner’s 2A supplemented with 4 % sodium bicarbonate, or equivalent. Blood or chocolate agar shall not be used. Incubation temperatures of 17 °C to 23 °C, and an incubation time of 168 h (7 d) are recommended. Other test methods may also be used, provided such methods have been appropriately validated and compared to the cited methods.”
That wording has been replaced in the ANSI/AAMI 13959:2014 with the following:
“Approved culture methods shall include one of the following:
- tryptone glucose extract agar (TGEA) or Reasoner’s 2A supplemented with 4% sodium bicarbonate, or equivalent. Blood or chocolate agar shall not be used. Incubation temperatures of 17°C to 23°C, and an incubation time of 168 h (7 d); or
- Trypticase soy agar (TSA, a soybean casein digest agar) or standards method agar and plate count agar (also known as TGYE), incubated at 35°C for 48 hours.
Other test methods may also be used, provided such methods have been appropriately validated and compared to the cited methods. See USP <1231> for guidance on adoption of alternative methods.”
The deviation of test methods surrounding agar medium, incubation temperature and incubation time was not adopted by ISO, but is now found within the latest ANSI/AAMI 13959 document as a deviation.
Chemical contaminates are also regulated so as to monitor the maximum allowable levels of toxic chemicals and dialysis fluid electrolytes in the water used for dialysis treatments. There are regulations that list the maximum allowable levels of other trace elements in dialysis water. Testing for these contaminants is commonly referred to as an ‘AAMI Test’.
Testing or sampling is very important and this Standard includes a fair amount of information detailing good sampling techniques, appropriate sample port location sites, and acceptable test methods as well as culture media. Test methods for chemical contaminates is also provided in table formats.
Finally, it includes a section that explains the rationale for the development and the provision of the Standard itself. Here microbial and chemical contaminates are discussed further so as to explain in greater detail a particular topic or reason for established practices.1