Background: System clotting and the anticoagulation techniques employed to prevent it are important causes of morbidity in continuous renal replacement therapy (CRRT). Different means have been employed in attempts to prolong system lifespan while minimizing complications.
Subjects, materials and methods: To determine whether augmenting blood flow and flush frequency could reduce clotting frequency, we compared system lifespan in a standard blood flow and saline flush group (125 ml/min and 100 ml once hourly, respectively) to an augmented blood flow and saline flush group (200-250 ml/min and 100 ml twice hourly). A total of 34 patients treated with continuous venovenous hemodialysis were randomized to receive either the standard or augmented regimens in a prospective trial conducted between August 1995 and March 1997. A total of 130 systems were studied.
Results: Based on intention-to-treat analysis, there was no difference in time to clot between the two groups. In a multivariate analysis of the outcome, red blood cell and platelet transfusion during CRRT were significantly associated with decreased clotting, and systemic heparin infusion significantly prolonged lifespan of CRRT systems.
Conclusion: Increasing blood flow and flush frequency does not prevent clotting in CRRT. Since this intervention is more costly than standard treatment, its use cannot be justified.