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BACKGROUND: Central dialysate fluid delivery systems (CDDS) are used by dialysis centers in Japan, and although these systems are effective at delivering dialysate, they have a complex piping network with numerous sites where contamination can develop. In Japan, cleaning disinfectants have been clinically evaluated based on endotoxin levels and bacterial counts, but there have been no published studies evaluating the biofilm removal efficacy of these agents at the electron microscope level. OBJECTIVES: In this study, we used electron microscopy to evaluate the effectiveness of various cleaning disinfectants in removing biofilms from hemodialysis piping. METHODS: Liquid nitrogen was used to sever a section of dialysis piping on which a biofilm had formed during clinical use. Sodium hypochlorite, acetic acid, and peracetic acid were used at stock-solution concentrations as cleaning disinfectants. These disinfectants were tested at room temperature and when heated (80°C). After cleaning and disinfection, biofilm removal from the surface of the piping was evaluated using a scanning electron microscope (SEM). RESULTS: Sodium hypochlorite did not show good biofilm removal at room temperature or when heated. Acetic acid was more effective at biofilm removal when heated than at room temperature. Peracetic acid was highly effective at biofilm removal at both room temperature and when heated. CONCLUSIONS: Cleaning and disinfection using a disinfectant at a high temperature and high concentration effectively removes biofilms from hemodialysis piping. However, long-term exposure to disinfectants may affect the piping material.

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Continuous hemodiafiltration using a hemofilter made from a membrane with cytokine adsorption properties is thought to be effective to remove cytokines in septic patients. In order to enhance cytokine removal capacity by increasing adsorption area, we devised a double polymethyl methacrylate continuous hemodiafiltration method, which involves serial connection of two polymethyl methacrylate membrane hemofilters, and we report clinical efficacy with this method. Of 74 patients who underwent continuous hemodiafiltration and had interleukin-6 blood levels measured during their ICU stay between March 2010 and June 2012, 13 patients with hypercytokinemia (interleukin-6 blood level >900 pg/mL) underwent series double continuous hemodiafiltration to be treated for hypercytokinemia. Cytokine reduction rate and clinical efficacy were compared between those 13 patients and those with a similar pathological condition who underwent continuous hemodiafiltration using the single polymethyl methacrylate membrane hemofilter. Interleukin-6 blood levels 6 h after continuous hemodiafiltration initiation increased in the single continuous hemodiafiltration group from 17040 ± 33660 pg/mL to 26290 ± 66250 pg/mL; however, interleukin-6 blood level significantly decreased in the series double continuous hemodiafiltration group from 20220 ± 29120 pg/mL to 6790 ± 10820 pg/mL. Interleukin-6 reduction rate during the period between initiation and 6 h after initiation of continuous hemodiafiltration was significantly higher in the series double continuous hemodiafiltration group(63.5 ± 38.9%) compared to that of the single continuous hemodiafiltration group (-342 ± 1306%)(P = 0.039). Series double continuous hemodiafiltration using two polymethyl methacrylate hemofilters with cytokine adsorbing capacity is effective to remove cytokine in hypercytokinemic septic patients.

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For dialysis fluid quality criteria, several dialysis centers in Japan have put great effort into keeping endotoxin (ET) levels low, although in many countries the bacterial count measurement for dialysis fluid is widely used. The International Organization for Standardization (ISO) suggests an ET and bacterial level for dialysate fluid quality, and Japan currently also measures the bacterial count. Each country presses forward to revise their domestic criteria based on ISO suggestions. In some Japanese cities, guidelines are currently made for dialysate fluid quality control by referring to ISO values. In many countries it is necessary to push forward these domestic guidelines to hemodialysis centers to keep a low level of ET and bacteria. As one of several actual data, we will describe the ET concentration and bacterial count of dialysis fluid in many Japanese dialysis centers to make clear the relation between ET level and bacterial count.

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