Anwendung von niedermolekularem Heparin bei Hämodialysepatienten

Summary

Low-molecular-weight (LMW) heparin has been compared to standard unfractionated (UF) heparin in a total of 49 patients on hemodialysis and hemofiltration in order to determine the necessary therapeutic dose and its effect on the coagulation system. A LMW heparin dose corresponding to 50% of the normal UF heparin dose was found to produce similar plasma heparin levels (anti-FXa-U/ml) in particular on minimal heparinization. At higher doses, UF heparin produced a more marked increase in plasma-heparin than did LMW heparin. Highly significant differences were found between UF and LMW heparin in their effects on PTT and thrombin time. Partial thromboplastin time (PTT) increased under UF heparin by an average of 120 s whereas LMW heparin only produced an increase of 5–7 s. Thrombin time was increased by 250–280 s under UF heparin and by 5–8 s under LMW heparin. With this LMW heparin dose of 50% of the UF heparin dose, no thrombosis of the extracorporal system occurred and no macroscopic detectable thrombotic material was found in the dialyzers or filters. No significant differences were observed between the effects of UF and LMW heparin on Factor VIII activity and fibrin monomers, so that a difference in coagulation activation between the two heparins can be excluded. Furthermore, there were no changes in thromboplastin time according to Quick, fibrinogen, antithrombin III, plasminogen, and a₂-antiplasmin. Thus effective Anti-FXa levels and by similar antithrombotic activity, LMW heparin will probably present less of a bleeding risk because of its reduced effect on PTT and thrombin time. LMW heparin therefore appears to be a good alternative to UF heparin for patients with renal insufficiency requiring dialysis. LMW heparin is indicated in particular in patients at bleeding risk, with diabetic retinopathy, on therapy with oral anticoagulants or platelet aggregation inhibitors, and with thrombocytopenia.