Background: Regional citrate anticoagulation or saline flushes are often used in haemodialysis patients at high risk of bleeding. In an alternative approach we evaluated the effects of covalent circuit coating with low molecular weight heparin (LMWH) for intermittent haemodialysis.
Methods: In vitro, we compared the thrombogenicity of an uncoated polyvinylchloride (PVC) tubing set with LMWH-coated tubing (AOThel) and a reference tubing with end-point attached heparin coating (Carmeda Bioactive surface) under dynamic blood contact. In vivo, five chronic haemodialysis patients were studied using the Genius dialysis system and F60S filters. Each patient underwent three dialysis sessions separated by a standard haemodialysis each: (1) standard dialysis (uncoated circuit and regular dalteparin dosage), (2) dialysis with LMWH-coated circuit and regular dalteparin dosage and (3) dialysis with a completely LMWH-coated circuit without anticoagulant use.
Results: In vitro, both coated tubings showed significantly reduced thrombin-antithrombin (TAT) complex levels compared with PVC. The reference coating (Carmeda) released substantial antifactor Xa (antiXa) activity into the plasma. The LMWH coating (AOThel) released low antiXa activity only during the initial rinsing. In vivo, all dialysis sessions were well tolerated and completed without major clotting. Antithrombin levels and platelet counts were similar in all groups. P-selectin and D-dimer levels increased similarly in all groups. TAT levels were comparable in all groups during the first 3 h and significantly increased in the anticoagulant-free group after the fourth hour.
Conclusions: LMWH surface coating reduces thrombogenicity in vitro without releasing significant amounts of heparin from the surface. In vivo, anticoagulant-free haemodialysis using a completely LMWH-coated circuit is feasible and safe in stable chronic dialysis patients with normal coagulation.