Endotoxin Size in Hemodialysis Solutions: Modifications in Presence of Concentrated Salt Solutions and Bacterial Products

Abstract

Pyrogenic reactions for which no cause can be found are common in hemodialysis, using non-sterile concentrated salt solutions and membranes which usually retain endotoxins (pore size: 10,000 to 30,000 D). If we admit that endotoxins, the most important pyrogens, might be responsible for these observations, we have to prove that they can cross hemodialysis devices. It is recognized that lipopolysaccharides (LPS) can exist in different forms, aggregated, mono or bi-layer subunits. This has been related to the ionic conditions, the presence of detergent or EDTA (2, 5, 6). In hemodialysis, the extent of the pyrogenic episodes has been shown to depend not only on the presence of gram positive bacteria or, in some cases, Halobacterium species (3). These reactions have only been observed for 40 to 800 mmol.1⁻¹ HCO₃ solutions. We examined the possibility that, under the ionic conditions described above, endotoxins might be the cause of pyrogenic effects associated with hemodialysis. If this were true, we would expect that, after filtration under various conditions, residual endotoxin would be detected in ultra-filtered solutions. Two different procedures were used to meet most of the clinical conditions: filtration experiments were performed with ultra-filters (pore size: 20,000 to 100,000 D), or true hemodialysis devices. Endotoxins were associated with three hemolytic Staphylococcus and two other species commonly isolated in concentrated salt solutions. Moreover, it was known that the effect of toxic shock syndrome toxin (TSS — Staphylococcus) is potentiated by small amount of endotoxin (1), and this unexplained observation supports our Staphylococcus-endotoxin interaction study.