The Permeability of Dialytic Membranes to Endotoxins: Clinical and Experimental Findings:

This study of 20 endotoxemic patients submitted to 70 hemodialyses (HD) found a reduction of the pre-HD limulus amebocyte lysate (LAL) positivity in 50 HD (71%), without appreciable differences in terms of effectiveness between cuprophan and AN 69 membranes. To define the mechanisms responsible for the reduction in LAL positivity during HD, the membranes were used in two in vitro studies, the first of which showed that the LAL positivity of blood containing lipopolysaccharide (LPS), submitted to hemofiltration (HF) for 300 min, remained unchanged and the ultrafiltrate remained constantly LAL negative. These results suggest that the reduction in LAL positivity observed in HD in vivo, an expression of reduced endotoxemia, cannot be attributed either to the filtration of the LPS as such or to its fragmentation following blood-membrane interaction into theoretically less filtrable molecules or to mechanisms of LPS adsorption on the membrane. The in vivo reduction of LAL positivity is more likely due to remova...