Platelet activation and clotting cascade activation by dialyzers designed for high volume online hemodiafiltration

Hemodialysis patients are pro-thrombotic. Higher volume online postdilutional hemodiafiltration (OL-HDF), with increasing hematocrit increases the risk of clotting in the extracorporeal circuit (ECC). We wished to determine whether OL-HDF increased platelet activation and ECC clotting.

Coagulation parameters, platelet, white cell, and endothelial activation markers were measured at the start and end of dialysis sessions in 10 patients and also pre- and post-dialyzer after 15 minutes using two different dialyzers designed for high volume OL-HDF; cellulose triacetate (TAGP) and polysulphone (PS), and polyvinylpyrrolidone (PVP). Patients were anticoagulated with a heparin bolus.

At the start of OL-HDF, D dimers, thrombin antithrombin complexes (TATs), and soluble adhesions molecules (sICAM-1 and sVCAM-1) were increased. Post-treatment soluble P selectin (PS/PVP 26.7 ± 7.1 versus 36.6 ± 9.9; TAGP 28.7 ± 7.2 versus 43.5 ± 8.4 ng/ml, P < 0.001), and soluble CD40 ligand (PS/PVP 297 ± 228 versus 552 ± 272, TAGP 245 ± 187 versus 390 ± 205 ng/ml, P < 0.05) increased. Post-dialyzer concentrations increased versus pre-dialyzer for tissue factor (PS/PVP 117 ± 12 versus 136 ± 16, TAGP 100 ± 25 versus 128 ± 40 ng/ml, P < 0.05), factor VIIIc (PS/PVP 174 ± 54 versus 237 ± 83, TAGP 163 ± 60 versus 247 ± 102 IU/ml, P < 0.01), sVCAM-1 (PS/PVP 782 ± 64 versus 918 ± 140, TAGP 722 ± 121 versus 889 ± 168 ng/ml, P < 0.01), and D-dimers (PS/PVP 292 ± 132 versus 355 ± 167, TAGP 300 ± 129 versus 391 ± 171 ng/ml, P < 0.001). There was no macroscopic thrombus noted in the ECC, and no increase in microparticles, platelet factor-4, or TATs.

Despite being pro-thrombotic, with activation of platelets, and lymphocytes during passage through ECC, no macroscopic clotting, or increased TATs were noted during OL-HDF, and no major differences between cellulosic and polysulphone dialyzers.