The effect of oral anticoagulation on clotting during hemodialysis.
BACKGROUND
Between 5% and 10% of hemodialysis patients are treated with oral anticoagulants. It is currently unknown whether additional anticoagulation with heparin or low-molecular-weight heparin (LMWH) is needed to prevent clotting during hemodialysis.


METHODS
In this prospective, randomized, cross-over study 10 patients treated with oral anticoagulants (phenprocoumon) received either no additional anticoagulation or low dose dalteparin (bolus of 40 IU/kg body weight) before dialysis. Efficacy of hemodialysis was measured by normalized weekly Kt/V and urea reduction rate (URR). Thrombus formation was evaluated by measurement of D-dimer and inspection of air traps and dialyser.


RESULTS
The median international normalized ratio (INR) did not differ between both observation periods (phenprocoumon 2.2(2 to 3) vs. dalteparin 2.1(2 to 2.9). The anti-Xa level in dalteparin patients was 0.33 (0.27 to 0.38) IU/mL after 2 hours and 0.16 (0.03 to 0.23) IU/mL after 4 hours of hemodialysis. The median increase of D-dimer was significantly higher in patients without additional dalteparin therapy during hemodialysis (DeltaD-dimer 0.23 microg/mL vs. 0.03 mug/mL) (P= 0.0004). Complete thrombosis of the dialyser membrane occurred in one patient in the phenprocoumon group but in none with combined treatment. The extent of thrombosis in the arterial and venous air trap and dialyser was significantly less in patients with additional dalteparin therapy (P= 0.0014, P= 0.0002, and P= 0.0005, respectively). Weekly Kt/V and URR was similar in both groups.


CONCLUSIONS
Standard oral anticoagulation with an INR between 2 and 3 is insufficient to prevent clotting during hemodialysis. Additional low dose anticoagulation with a LMWH or heparin is necessary to facilitate treatment.
Ziai
Farzad
F
Department of Internal Medicine III, Division of Nephrology and Dialysis, University Hospital Vienna, Vienna, Austria.
Benesch
Thomas
T
Kodras
Katharina
K
Neumann
Irmgard
I
Dimopoulos-Xicki
Lida
L
Haas
Martin
M
D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D001777:Blood Coagulation / Q000187:drug effects; D018592:Cross-Over Studies; D017985:Dalteparin / Q000008:administration & dosage; D004359:Drug Therapy, Combination; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010644:Phenprocoumon / Q000008:administration & dosage*; D011446:Prospective Studies; D006435:Renal Dialysis; D013927:Thrombosis / Q000517:prevention & control*
D000925:Anticoagulants; D005338:Fibrin Fibrinogen Degradation Products; D006495:Heparin, Low-Molecular-Weight; C036309:fibrin fragment D; D010644:Phenprocoumon; D017985:Dalteparin