Reprocessed (high-flux) Polyflux dialyzers resist trans-membrane endotoxin passage and attenuate inflammatory markers.

BACKGROUND

Bacterial contamination of dialysis water can contribute to the chronic microinflammatory state observed in dialysis patients. This study characterized the selective permeability of new and peroxyacetic acid/acetic acid/hydrogen peroxide (Renalin) reprocessed high-flux, polyarylethersulfone-polyvinylpyrrolidone (Polyflux-17R) dialyzers after exposure to endotoxin-contaminated dialysate during in vitro dialysis. Clinical correlation with pre-dialysis levels of systemic markers of inflammation, and clearance of middle molecules was also assessed in vivo.

METHODS

Six hemodialysis (HD) patients were enrolled in the study. After reuses 0, 1, 5, 10, and 15, the dialyzers were reclaimed and submitted to an in vitro dialysis circuit using standard dialysate and blood from healthy volunteers. New and reprocessed dialyzers were sequentially exposed to escalating doses of Pseudomonas aeruginosa endotoxin in the dialysate compartment, and whole blood tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production was used as an index of reverse passage of endotoxin. In vivo, IL-6, C-reactive protein (CRP) and serum amyloid A (SAA) levels were measured to assess the impact of reprocessing on the systemic inflammatory response. Finally, pre- and post-dialysis samples were collected to measure urea and beta(2)-microglobulin (beta(2)-M) clearances.

RESULTS

During in vitro dialysis, blood-side endotoxin levels were undetectable following dialysate contamination. TNF-alpha production remained unchanged (p = NS), and IL-6 production fell significantly on reuses 0, 1, 10, and 15 (p = 0.03) suggesting membrane adsorption, as a result of reuse-dependent surface binding. In vivo, whereas IL-6 and SAA levels did not significantly differ (p = 0.90 and 0.59, respectively), CRP levels fell near significantly, over the course of 15 reuses (p = 0.06). In vivo, beta(2)-M clearance was not affected by the reuse technique (p = 0.28).

CONCLUSIONS

This study provides in vitro and in vivo evidence arguing that high-flux Polyflux dialyzers provide more than adequate dialysis, while preventing the in vitro back-diffusion of bacterial endotoxin despite 15 reuses with Renalin. Clinically, this may translate into an attenuation of the microinflammatory milieu.