[Safety controls in a new hemodiafiltration on line technique (PHF)].

Purpose: On-line hemodiafiltration (HDF) is gaining popularity due to increasing evidence of clinical benefits. The purpose of this study was to test a new on-line technique paired hemodiafiltration (PHF). In addition, we evaluated the PHF system during in vitro contamination.

Methods: Five patients used the PHF technique over a 6-month period. We performed a disinfection protocol and tested for bacteria, endotoxin, halogenated carbons and metals in the feed water, and we tested for bacteria, endotoxins and fungi in the dialysate after different ultrafiltration stages. In vitro tests were performed using three bacterial concentrations of pseudomonas aeruginosa. Samples were analyzed from different sites throughout the entire on-line HDF circuit for bacteria endotoxins, fungus and the ability to stimulate whole blood production of tumor necrosis factor-alpha (TNF-alpha).

Results: The bacteriological control from the feeding machine water and at the entrance to the monitors had a bacterial level of <100 CFU/mL. No bacteria were detected in the dialysate and endotoxin levels were <0.03 EU/mL. In the in vitro contamination study, with the three bacterial concentrations tested at various points in the circuit, bacterial and fungi were below the level of detection and endotoxins were <0.03 UE/mL. The addition of dialysate samples taken after the 1st microfiltration stage, as well as after the 1st and 2nd ultrafiltration stage and incubated with whole blood were not associated with stimulated TNF-alpha production.

Conclusions: PHF appeared to be a safe and feasible method for on-line HDF even in the unforeseen presence of the bacterial contamination of the feed water or in the water distribution system.