Pyrogen retention by the Asahi APS-650 polysulfone dialyzer during in vitro dialysis with whole human donor blood

The purpose of this study was to test the pyrogen permeability of the new Asahi polysulfone APS 650 (APS) dialyzer membrane with a high permeability for middle molecules (up to 40 kDa) in comparison with the high-flux Fresenius polysulfone F60S (F60S) membrane. Dialyzers were tested in parallel in vitro dialysis experiments with whole human donor blood in the blood compartment and contaminated bicarbonate dialysate in the dialysate compartment. Dialysate was contaminated by a filtrate (0.45 microm) of a Pseudomonas aeruginosa culture in bicarbonate dialysate. The production of interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha) in whole blood samples taken from the in vitro dialysis system was used to detect the passage of cytokine inducing bacterial substances derived from P. aeruginosa across the two highflux polysulfone membranes. Compared with a sterile control period at the beginning of each experiment (n = 5), the TNFalpha inducing activity in the dialysate increased from (mean +/- SEM) 42 +/- 12 pg/ml to 1,288 +/- 356 pg/ml with F60S dialyzers and from 37 +/- 10 pg/ml to 928 +/- 249 pg/ml with APS dialyzers 30 minutes after the dialysate was contaminated. The IL-1beta inducing activity in the dialysate increased similarly. In the presence of this significant contamination in the dialysate, whole blood circulating in the blood compartments for 60 minutes was not stimulated to produce increased amounts of TNFalpha or IL-1beta with neither of the two tested membranes. We conclude that F60S and APS membranes are equal in their ability to prevent the passage of cytokine inducing bacterial substances from highly contaminated dialysate into the patients' blood during hemodialysis.