Permeability of dialysis membranes for endotoxins. Clinical and experimental results

In the presented investigation in 20 endotoxaemic patients 70 haemodialyses were performed. It was revealed that the prehaemodialyzation LAL positivity in 50 haemodialyses (71%) declined, while no differences were observed in the effectiveness of cuprophan and AN 69 membranes. Research in vitro revealed that LAL positivity of blood which contains endotoxins and is subjected for 300 minutes to haemofiltration remains unaltered; in ultrafiltrates LAL is permanently negative. This is due to a mechanism of endotoxin fragmentation as a result of interaction of blood and membrane. Moreover, the LAL positivity of blood containing lipid A declines gradually when subjected to 80 minutes haemofiltration; the dialyzation permeability for lipid A is then proved by the fact that LAL positivity appears in the ultrafiltrate. From the submitted results ensues that reduction of LAL positivity by haemodialysis occurs as a result of elimination of filtrable endotoxin fragments (lipid A) which are released in the body.