High-permeable membranes and hypersensitivity-like reactions: role of dialysis fluid contamination.

We have recently observed repeated hypersensitivity-like reactions (skin flush, face and tongue tingling, hypotension, and dispnea) during the first 5 min of dialysis in a small number of our dialysis population treated with high-flux membranes and traditional acetate dialysate. This prompted us to investigate the relationship between these reactions and the presence of contamination of the dialysate fluid. We hypothesized that in the presence of contaminated dialysate fluid and high-flux membranes backfiltration of pyrogens may occur through the membrane into the blood compartment, leading to hypersensitivity-like reactions. These events are more likely to occur at the onset of dialysis due to rapid changes of hydrostatic pressure gradients across the dialysis membranes. 6 out of 48 dialysis patients who experienced hypersensitivity-like reactions were followed for 4 weeks. During the 1st week they were treated with high-permeable membranes and during the 2nd week with cuprophane membranes. The dialysate showed high levels of contamination with bacteria and endotoxin during dialysis with both types of membranes (microbial count 4,123 +/- 2,756 and 1,991 +/- 1,950 colony-forming units/ml; endotoxin 26.2 +/- 8.4 and 23 +/- 4.2 endotoxin units/ml, respectively); however the symptoms occurred only during dialysis with high-flux membranes. This suggests that backfiltration of contaminated dialysate into the blood might have occurred during the early phases of dialysis only when using high-flux membranes, but not when using cuprophane membranes. To test this possibility we introduced a new dialyzer-rinsing device consisting of two simple connection lines which allow to rinse, in a concurrent manner, the dialysate and the blood compartments of the dialyzer with sterile saline solution.(ABSTRACT TRUNCATED AT 250 WORDS)