Arena Service Manual
Water processed by the various components of the water
purification system to remove harmful chemicals including
chlorine can encourage bacteria growth due to the absence of the
chlorine (AAMI, 1990, pp. 81-94).
Most equipment used for water purification does little to decrease
the bacteria. In some cases, the water purification system can
increase the total microbial contamination count. This is
especially true when filters are not changed when required or when
recommended disinfection procedures are not being followed.
Reverse osmosis systems remove most of the bacteria, viruses, and
endotoxins, but low numbers of Gram-negative bacteria can grow
downstream. Routine disinfection is required to keep the bacteria
levels minimized (AAMI, 1990, pp. 81-94).
When the water is proportioned with concentrates, the resulting
dialysate becomes the food required by bacteria to increase growth
dramatically. Gram-negative bacteria growing in distilled,
deionized, or reverse osmosis water can reach levels of 10
5
to 10
7
cfu/mL. In contrast, these same bacteria growing in dialysis fluids
achieve levels of 10
8
to 10
9
cfu/mL
(AAMI, 1990, pp. 81-94).
9.9.2 Allowable Limits
Standards set by the Association for the Advancement of Medical
Instrumentation (AAMI) and the US Food and Drug
Administration (FDA) state that 200 cfu (colony forming
units)/mL is the maximum allowable bacterial concentration in
product water used for dialysis purposes. AAMI RD62: 2001 has
also added an action level of 50 cfu/mL. If the test is above 50,
an action must be taken (such as disinfection of the loop and RO
system and reculturing).
The AAMI standard also states that the total microbial count in
proportioned dialysate should not exceed 2,000 cfu/mL.
It further directs that voluntary endotoxin (lipopolysaccharide)
levels in water used for reuse shall not exceed 1 ng/mL as
demonstrated by the Limulus amebocyte lysate (LAL) assay. In
the AAMI RD62: 2001 LAL testing is no longer voluntary. It is
required for all water used for dialysis purposes and should not
exceed 2 EU(endotoxin units)/mL with an action level of 1
EU/mL.
If the dialysate or the water used to prepare it exceeds the
allowable limit for bacteria and endotoxins, the dialysis patient can
exhibit clinical signs such as shaking, chills, fever, hypotension,
myalgia, nausea, and vomiting (pyrogenic reactions) and possible
9-36 157-1278-916, Rev A
March 2004
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