Central online hemodiafiltration in Japan: management of water quality and practice.

Hemodiafiltration (HDF) includes a variety of technologies and preparation of ultrapure dialysis fluid has made it possible to perform online HDF and its extensive alternatives. According to current statistics, 5.8% of ESRD patients are treated with HDF in Japan. The majority of these HDF treatments are performed using the central dialysis fluid delivery system (CDDS), this is because most Japanese clinicians and researchers consider that with CDDS it is easier to prepare substitution fluid; moreover, CDDS has economical advantages against single-patient dialysis machine (SPDM)-based counterparts. The water quality at each patient station (dialysis console) is regularly validated by bacterial culture (colony-forming units) and by measuring endotoxin concentration (ET). Since ET measurement takes much less time than bacterial culture, ET is often used as an indicator to verify the water quality for online use. Dialysis fluid with ET below the detection level (usually <0.001 EU/ml) is used for online substitution. In CDDS online HDF, since dialysis clinics must prepare not only the dialysis fluid but also the substitution fluid, they need to satisfy almost the same requirements as pharmaceutical water treatment factories do. The Japanese Society for Dialysis Therapy (JSDT) together with the Japanese Society for Hemodiafiltration (JS-HDF) is now preparing guidelines to meet all these necessary requirements on a worldwide basis.