P0238 ANTITHROMBIN SUPPLEMENTATION AFTER LIVER TRANSPLANTATION

Abstract

Introduction: After liver transplantation deficiencies of natural anticoagulants including antithrombin (AT) are associated with increased risk of hepatic artery thrombosis (HAT), a potentially fatal complication. Recently, AT supplementation was added to the routine management of children after liver transplantation in Queensland. We report the response to AT supplementation in six children so treated. Methods: All cases treated with AT after liver transplantation at Royal Children’s Hospital were retrospectively reviewed. Results: 6 children (3 male) aged 3 wks-1.5 y (median 1y) and weighing 4–10.8kg (median 8.9kg) were transplanted between June 2002 and March 2003 and received antithrombin. Transplant indications were: extrahepatic biliary atresia (n=3), cryptogenic cirrhosis (1), ornithine transcarbamylase deficiency (1) and idiopathic acute hepatic failure (1). Grafts were reduced (3), split (1) and whole (2) cadaveric organs. All received routine post-op care, including triple drug immunosuppression (tacrolimus, azathioprine and methylprednisolone). Prostaglandin E1 infusion was started intra-operatively to enhance hepatic blood flow: dose 0.02 mcg/kg/min, continued post-op for 24 hours. Pro-phylaxis with AT and low dose heparin (load of 75u/kg followed by infusion of 10 u/kg/hr, aiming for minimal / no change in APPT) was commenced immediately post-op in 5 and on day 6 post-op in the other case, after detection of reduced hepatic artery flow (no thrombus). AT and heparin were continued for 10 days postop. AT dosage was 70–10 0 IU/kg, titrated to keep trough levels (taken 18–21hours post dose) > 0.7 IU/mL (NR 0.79–1.31). Patients’ pretreatment AT levels were 0.43–0.57 IU/mL (median 0.52 IU/mL) and post-infusion were 1.19–1.83 IU/mL (median 1.5I IU/mL). AT was well tolerated. One patient bled from the cut surface of the graft, requiring transfusion. No other hemorrhagic complications occurred and there were no cases of HAT. By comparison, in a group of 23 historical controls transplanted at this center, aged 0–1.5years at transplant (median 1.15y), weight 3.8–12.5kg (median 8.9kg)(p=NS vs current series), the rate of HAT was 22%. Conclusion: Post-transplantation AT supplementation was well tolerated in this group of infants. Due to their small size, age and low initial AT levels this group was considered to be at high risk of HAT. The absence of HAT in this cohort suggests that AT supplementation is effective for the prevention of HAT after liver transplantation and that further research on this agent is warranted.