Bivalirudin versus Unfractionated Heparin for Prevention of Hemofilter Occlusion During Continuous Renal Replacement Therapy

Study Objective. To evaluate the safety and efficacy of bivalirudin compared with heparin for preventing hemofilter occlusion during continuous venovenous hemofiltration (CVVH). Design. Prospective, randomized, double-blind study Setting. University-affiliated hospital. Patients. Ten critically ill adults (median age 58 yrs, 70% male) with acute renal failure who, without anticoagulation, experienced hemofilter survival time of 24 hours or less during CVVH. Intervention. Patients were randomized to receive bivalirudin 2 mg/hour (five patients) or heparin 400 units/hour (five patients) administered prefilter into the extracorporeal circuit. Measurements and Main Results. Patients had a median Acute Physiology and Chronic Health Evaluation (APACHE) II score of 24, Sequential Organ Failure Assessment (SOFA) score of 11, and reduced antithrombin activity (75.5 units/dl). Baseline characteristics were not significantly different between groups. Study drug was administered in 40 hemofilters (18 from bivalirudin-treated patients, 22 from heparin-treated patients). The primary efficacy outcome was hemofilter survival time, defined as the interval of time between commencement of CVVH with a new extracorporeal circuit (hemofilter) and hemofilter failure. Compared with no anticoagulation, the addition of bivalirudin or heparin significantly improved hemofilter survival time (mean +/- SD 10 +/- 5 hrs with no anticoagulation vs 22 +/- 18 hrs with anticoagulation, p=0.0005). Hemofilter survival time was significantly increased in patients receiving bivalirudin versus those receiving heparin (29.6 +/- 20.7 vs 16.5 +/- 13.6 hrs, p=0.045). Independent predictors of hemofilter survival were use of bivalirudin therapy and increased antithrombin III activity. No patients randomized to bivalirudin experienced any bleeding or thrombosis events; one patient who received heparin developed alveolar hemorrhage, and one developed a lower extremity deep vein thrombosis. Conclusion. Compared with heparin, bivalirudin was more efficacious in prolonging hemofilter survival time and was well tolerated. Additional studies of bivalirudin for prevention of hemofilter occlusion during continuous renal replacement therapy are warranted.