Ultrapure dialysis fluid: Improving conventional and daily dialysis

Abstract

Dialysis fluid of standard quality contains a certain amount of bacteria and endotoxin. This has been considered acceptable because the dialysis membrane was believed to be a protective barrier to blood. However, improved methods for detection of cellular activation have demonstrated that bacterial products in the dialysate may stimulate monocytes to produce cytokines with most dialysis membranes. Ultrapure dialysis fluid is practically free from bacteria and endotoxin (< 0.1 CFU/mL and < 0.03 EU/mL) and can be prepared from standard-quality dialysis fluid using a single step of controlled ultrafiltration. The European guidelines for hemodialysis (HD) set the use of ultrapure dialysis fluid as the goal for all dialysis modalities. Several clinical studies report improved inflammatory status in HD patients when ultrapure dialysis fluid is used, compared with standard-quality dialysate. The benefits include less frequent occurrence of carpal tunnel syndrome, lower C-reactive protein values, reduced need for erythropoietin, better nutritional status, and even better preservation of residual renal function. For patients on daily dialysis, dialysate quality is especially important because such patients are often treated at home where quality control of incoming water may be less rigorous, and increased treatment frequency leads to exposure to larger volumes of dialysis fluid than with conventional dialysis. The use of ultrapure dialysis fluid together with low-complement-activating membranes maximizes the biocompatibility of a dialysis treatment, a goal of treatment, although there is a lack of evidence to date supporting a beneficial effect on mortality. From a physiologic point of view the reduced inflammatory stimulus that can be achieved with ultrapure dialysis fluid is highly desirable. In addition, achieving ultrapure dialysis fluid is realistic, because today it can be practically and economically prepared using modern equipment and applying appropriate microbiologic surveillance techniques.