Evaluation of bivalirudin treatment for heparin-induced thrombocytopenia in critically III patients with hepatic and/or renal dysfunction

Study Objective. To evaluate the safety, effectiveness, and dosing of bivalirudin for treatment of heparin-induced thrombocytopenia (HIT) in critically ill patients with hepatic and/or renal dysfunction. Design. Retrospective cohort study. Setting. University-affiliated medical center Patients. Eighteen patients older than 18 years who were admitted to the intensive care unit (ICU), had hepatic and/or renal dysfunction, and were treated with bivalirudin for the diagnosis of HIT between January 1, 2004, and March 31, 2005. Measurements and Main Results. Patient records were reviewed for dosage and duration of bivalirudin therapy, occurrence of thrombosis, and clinically significant adverse effects. Of the 18 patients identified, 12 had both hepatic and renal dysfunction (group 1), four had hepatic dysfunction (group 2), and two had renal dysfunction (group 3). Demographics were similar among the groups. Mean +/- SD age was 54 +/- 15 years and weight was 82 +/- 14 kg, 67% were male, 83% were Caucasian, and 56% were receiving renal replacement therapy Mean bivalirudin doses were 0.06 +/- 0.15 mg/kg/hour (median 0.03 mg/kg/hr), 0.14 +/- 0.05 mg/kg/hour (median 0.14 mg/kg/hr), and 0.05 +/- 0.01 mg/kg/hour (median 0.05 mg/kg/hr) for patients in groups 1, 2, and 3, respectively. Ten patients receiving continuous venovenous hemofiltration with or without dialysis received a mean dose of 0.04 +/- 0.03 mg/kg/hour (median 0.03 mg/kg/hr). in the 18 patients, mean bivalirudin duration was 15 +/- 17 days, activated partial thromboplastin time (aPTT) was 69 +/- 22 seconds, and international normalized ratio was 2.2 +/- 0.8. Supratherapeutic aPTTs were most common on days 1 (22%) and 2 (28%) when bivalirudin doses were highest. Clinically significant bleeding did not occur in any patient. Thrombosis occurred in one patient (6%) while receiving bivalirudin. Conclusion. Patients in the ICU who have hepatic and/or renal dysfunction require low doses of bivalirudin to achieve aPTT values 1.5-2.5 times baseline. Bivalirudin can be safely started at 0.14 mg/kg/hour in patients with hepatic dysfunction, 0.03-0.05 mg/kg/hour in those with renal or combined hepatic and renal dysfunction, and 0.03-0.04 mg/kg/hour in patients receiving continuous renal replacement therapy.