Heparin vs recombinant hirudin for anticoagulation in continuous renal replacement therapy

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Introduction

Heparin as standard for anticoagulation in continuous renal replacement therapy (CRRT) has a bleeding incidence of 20% and is contraindicated in patients with heparin induced thrombocytopenia II [1]. Recently recombinant hirudin (rhirudin) has been reported to be superior as an anticoagulant to heparin for intermittent hemodialysis [2]. The aim of the study was to compare heparin and rhirudin as anticoagulants in CRRT regarding hemofiltration efficacy and possible bleeding complications.

Methods

After ethical committee approval and written informed consent from the relatives 16 critically ill patients with an indication for CRRT were randomly allocated to 2 groups: heparin (9 patients) initially 250 IU/h; target activated clotting time (ACT) 180–210 s, 125 IU/h stepwise heparin dose change; hirudin (8 patients) initially 10 μg/kg/h; target ecarin clotting time (ECT) 80–100 s, 2 μg/kg stepwise dose change. Every four h, thrombin time (PT), partial thromboplastin time (PTT), hemoglobin (Hb) and thrombocytes were determined. A bleeding complication was defined as an Hb decrease >2 g/dl. The observation time was 96 h. The ocurrence of filter clottings were recorded.

Statistical analysis

Mann-Whitney-U-Test, P ≤ 0.05.

Results

Basic patient characteristics did not differ between groups.

Three bleeding complications were observed in three patients in the rhirudin group, but none were seen in the heparin group. The bleedings were observed 60 h after study initiation. Platelets were 76, 14 and 62/nl at bleeding time. The ECT was 83, 65 and 85 s respectively. PTT was higher than 60 s and PT was lower than 60 s at this point in all three patients. rhirudin application was interrupted 4 and 8 h before bleeding time point in two patients, the third patient received 5 μg/kg/h rhirudin.

Conclusion

Rhirudin prevented filter clotting more effectively than heparin. Low platelet count together with pathological PT and PTT, despite aimed or low ECT in patients with bleeding complications, indicated that improved clotting monitoring and dose adjustment must be implemented before rhirudin can be used safely.

Table 1 Filter clotting and run time; median (range)