The cleaning and disinfecting of hemodialysis equipment using electrolyzedstrong acid aqueous solution

In general, sodium hypochlorite, formalin, and Dialer (Teijin Gambro Medica l, Ltd., Tokyo, Japan [main ingredients: H2O2, CH3CHOOOH, CH3COOH, H2O]) ar e used to clean and disinfect hemodialysis pipelines. In this study, the su itability of electrolyzed strong acid aqueous solution (ESAAS), which has a ttracted considerable interest in Japan because of its strong disinfecting properties, was examined. The crossover method was used to investigate the effectiveness of ESAAS in disinfecting the dialysis pipelines in comparison to that of sodium hypochlorite (200 ppm) used alternately with 1% acetic a cid. The number of bacteria and the concentration of endotoxin (Et) were me asured over an approximately 3 year period, starting in September 1994. Unt il then, 200 ppm sodium hypochlorite had been used alternately with 1% acet ic acid, and the contamination of the pipeline had been marked. However, af ter switching to the ESAAS disinfection method, the dialysis pipelines very rapidly became cleaner. Therefore, the decision to develop an automated ES AAS cleaning system for long-term use was made. During the development peri od, the original disinfectants (200 ppm sodium hypochlorite used alternatel y with 1% acetic acid) were used as a stopgap. After confirmation of its pe rformance and safety, the automated ESAAS cleaning system was introduced. T o find out whether the decrease in bacteria secondarily caused a decrease i n the Et concentration or whether the ESAAS directly inactivated the Et, an in vitro experiment was carried out. Highly concentrated Et, which had bee n left in the reverse osmosis (RO) drainage pipeline, was used as a sample to investigate the effects of ESAAS on Et at various concentrations and tem peratures and on the recovery test. The results showed that ESAAS directly inactivated Et. This paper reports the results of the crossover test. The r esults of parallel tests carried out over an approximately 4 year period ha ve already been reported. No significant problems occurred in the dialysis. The automated ESAAS cleaning system that was developed proved to be more e conomical than the conventional disinfecting method.