Originally posted by pato: Could you tell me why there is a greater limit for dialysate (< 2000 cfu/mL) than for water [<200 cfu/mL)? Thanks.
Good question... I never have really got a straight answer on that. However, I believe it's because bicarb and acid aren't as 'controlled' as the water is, particularly the bicarb because bicarb is much more likely to become home to bacteria. Therefore, when mixed together to form dialysate, which has an optimal pH and temperature for growth, a higher count is more likely. Anyone that feels my theory is wrong, feel free to set the record straight, it just makes sense to me.
Posts: 575 | Location: Midwest | Registered: 22 December 2002
We use dry powder bicarb cartridges so bicarb is made 'on line'. Dry powder does not grow bacteria. The producers (and others) of the 'A' concentrate say that the strong salt solution inhibits bacterial growth. The only other source of contamination is therefore the machine fluid path and inlet hoses.
Incidentally, we aim for <0.1 CFU and <0.03IU from our water system and <10 CFU from the dialysate.
The 2000 cfu/ml AAMI limit for dialysate was originally set because the great majority of dialysis machines recirculated the dialysate throughout the treatment (anyone remember the good ole coil dialyzers?) and bacterial growth was expected.
The new AAMI limit for dialysate is 200 cfu/ml but this has yet to be adopted by CMS as regulation.
A couple sidenotes: Even 2000 cfu is a very small anount of bacteria. If it were a wound or blood culture, most labs would report it as being negative.
Intact bacteria are too large to pass through the dialyzer membrane but they must be controlled because if a biofilm would develop, you stand a much higher risk for pyrogenic reactions because endotoxin will cross the membrane.
Posts: 872 | Location: Baltimore, MD USA | Registered: 24 October 2001
Are ANY of the limits discussed in this string actually "approved" or "adopted" by CMS or the FDA? They have been published by AAMI, they are a good idea, but are they actually "law" ?
They have contact information on their site. They will send you (for a fee) their current standards. What they send you will be THEIR current standards, CMS has not adopted these as of yet (the wheels of government turn slow).
Posts: 872 | Location: Baltimore, MD USA | Registered: 24 October 2001
