Background: Inadequate antifactor Xa levels have been documented in critically ill patients given prophylactic enoxaparin and may result in increased risk of venous thromboembolic (VTE) events. The objective of this study was to examine the impact of dose adjustment of enoxaparin and associated incidence of VTE in acute burn patients.
Methods: All acute burn patients who were treated with prophylactic enoxaparin on a burn/trauma intensive care unit were prospectively followed. Patients with subtherapeutic antifactor Xa levels had enoxaparin doses increased as per unit protocol with the goal of obtaining a therapeutic antifactor Xa level.
Results: Eighty-four acute burn patients who were treated with enoxaparin had at least one appropriately obtained antifactor Xa level between June 2009 and October 2010. Initial antifactor Xa levels in 64 patients (76.2%) were below 0.2 U/mL, resulting in increased enoxaparin dose. Fifteen patients never achieved the target antifactor Xa level before enoxaparin was discontinued. Median final enoxaparin dose required to achieve therapeutic antifactor Xa levels was 40 mg every 12 hours (range, 20-70 mg). Using linear regression, final enoxaparin dose correlated with burn size (%total body surface area) and weight. No episodes of hemorrhage, thrombocytopenia, or heparin sensitivity were documented. Two patients (2.4%) had VTE complications despite adequate prophylaxis.
Conclusions: Frequent occurrence of low antifactor Xa levels observed in this study demonstrated the inadequacy of standard dosing of enoxaparin for VTE prophylaxis in many patients with acute burns. Enoxaparin dose adjustment was associated with a low incidence of VTE events and no bleeding complications.