The purpose of this study is to determine whether the heparin-coated dialysis filter is superior to a conventional filter during hemodialysis in twelve stable, chronic hemodialysis (HD) patients.

The antithrombogenic properties of the heparin-coated dialysis filter and of the conventional filter will be compared by means of statistical tests.

In the present study twelve chronic hemodialysis (HD) patients will be included. Exclusion criteria are use of acetylsalicylic acid and/warfarin, clinical signs of infection and disseminated malignant disease. For each patient four HD sessions will be investigated; alternating with use of the pre-heparin-coated filter or the conventional filter. Dalteparin is reduced to 50% of the conventional dose and is given as one single bolus dose at start of HD.

The venous drip chamber will be visually inspected for evaluation of clot score during each HD session. The filter will be visually inspected for clot score at the end of each session.

Blood specimens will be drawn systematically during each HD session to evaluate platelet and coagulation activity as well as anti Factor Xa activity, haematology and urea/creatinine to evaluate dialysis effect.

The antithrombogenic properties of the pre-heparin-coated filter and the conventional filter will be compared by means of statistical tests. The hypothesis is that the pre-heparin-coated filter induces significantly less clot score in the extracorporeal system during hemodialysis and also significantly less intravascular activation of the coagulation system compared to the conventional filter.

Inclusion Criteria:

• Stable HD patients of at least 18 years of age.
• HD treatment for at least one month.
• Dialysis time at least 4 hours three times per week.
• Stable Hemoglobin value of at least 11 g/dl during the last 4 weeks.

Exclusion Criteria:

• Use of warfarin and/or acetylsalicylic acid.
• Disseminated malignant disease.
• Clinical signs of infection.