The Impact of Antithrombin III Use in Achieving Anticoagulant Goals in Pediatric Patients.

OBJECTIVES: To determine the percentage of patients with >10% reduction in heparin infusion rate within 48 hours of antithrombin III (ATIII) administration. Secondary objectives include the achievement of therapeutic anticoagulation and determining the days of subtherapeutic infusion prior to supplementation.

METHODS: Retrospective chart review of 12 patients younger than 18 years of age who received ATIII concentrate supplementation while on continuous heparin infusion. Specific indications for heparin infusion therapy included extracorporeal membrane oxygenation (ECMO), treatment of thrombus, and post implantation of ventricular assist device(s).

RESULTS: From time of heparin initiation to ATIII supplementation, patients spent a mean 4.9 ± 2.6 days of subtherapeutic infusion and required uptitration from a mean of 15.3 ± 4.4 units/kg/hr to a mean rate of 40.7 ± 9.5 units/kg/hr. 58.3% of the patients (n = 7) had a ≥10% reduction from the baseline heparin infusion rate within 48 hours of ATIII administration. Those patients considered responders (≥10% reduction from baseline rate) had a slightly higher mean baseline antithrombin level (76.3% ± 22.0% vs. 58.6% ± 2.7% in non-responders, p = 0.1) and were administered comparable doses of ATIII. ATIII supplementation did appear to increase the time of therapeutic anticoagulation within the 48 hours.

CONCLUSIONS: Administration of ATIII is associated with >10% decrease in heparin requirements in more than half of the patients identified. In those patients deemed non-responders, there was a trend towards lower baseline antithrombin serum levels. Further studies are warranted to determine if the lack of response in some patients is due to inadequate dosing of ATIII or any patient-related factors.