Evaluation of comparative thrombogenicity of cellulose-acetate hemodialyzer in in vitro and in vivo system with radiolabeled platelets

Platelet thrombus in the hemodialyzer, arterial and venous traps in the extracorporeal circuit was never quantified. Platelet consumption during hemodialysis was measured in Yorkshire pigs with In-111 labeled platelets. Six anesthetized pigs (20–25 kg) were hemodialyzed at 150 ml/min for 3 hours. All pigs were injected with autologous labeled platelets (300–420 μCi), 24 hours prior to dialysis and were systemically heparinized prior to cannulation. Hemodialysis was instituted with a dialyzer pump and hollow-fiber dialyzer (Cobe4,0.6 m²). In vitro sham-dialysis was carried out with 6 more dialyzers in a flow-loop using porcine blood at 150 ml/min. In vitro thrombogenicity was higher (10-fold) than in vivo values, thus overestimates in vivo values. In both systems platelet deposition on dialyzers reached a steady state, suggesting a constant rate of thrombus formation and embolization. The relative thrombus distribution in the dialyzer at 3 hours of dialysis was similar in both systems.