Bacteriological and Clinical Evaluation of Different Dialysate Delivery Systems

Abstract

In the period 1-74 four different dialysate delivery systems have been used in our department. 1 ) Central mixing of dialysate using tap water and a dialysate delivery line with "dead ends" resulting in stagnant dialysate. 2) Central mixing of dialysate with cold distilled water, otherwise equal to system 1. 3) Local mixing of dialysate with cold distilled water, delivered through a line with "dead ends" resulting in stagnant water. 4) Local mixing of dialysate with distilled water, cooled to 25°C just prior to use, reduced "dead ends" and monitored constant overflow to drain through the water supply line. The bacterial contamination of the four systems was examined and related to the clinical occurrence of pyrogenic and other reactions. An improvement was noted with the change from central to local mixing of dialysate (system 3) but complete sterility and virtual freedom from clinical reactions were first obtained in system 4. It is concluded that the use of sterile or near sterile dialysate is recommendable.

Should Hemodialysis Fluid Be Sterile?

“…These two outbreaks, plus a European study (2), formed the basis for the dialysate bacteriological standard of 52,000 cfu/ml adopted by the Association for the Advancement of Medical Instrumentation (AAMI). The water standard of 5200 cfu/ml was an arbitrary value based on an anticipated one log increase in bacterial contamination as water is mixed with dialysate concentrate, heated, and circulated through the dialysis machine.…”

“…There are data that pyrogenic reactions are related to the number of bacteria in dialysis fluids. Based on these studies, the AAMI guidelines for bacteria counts in water of ~2 0 0 cfu/ml (but not necessarily sterile) were developed (2). These recommendations have been accepted by the U S .…”

Are Current Standards for the Microbiological Purity of Hemodialysate Adequate?

“…It is also difficult to conceive of endotoxin micelles crossing the protein retentive membranes used for hemodialysis. Nevertheless, studies have shown a correlation between levels of bacterial contamination of dialysate and the incidence of pyrogenic reactions (10,22). Although endotoxins exist largely as micelles, these micelles are thought to be in equilibrium with some small concentration of free endotoxin.…”