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Previous research has shown that inadequate antifactor Xa levels (anti-Xa) occur in burn patients and may increase the risk of venous thromboembolic events (VTE). The objective of this retrospective review was to investigate the usefulness of an enoxaparin dosing algorithm using a previously published equation. With institutional review board approval, all acute burn patients at an American Burn Association-verified regional burn center who were treated with enoxaparin for VTE prophylaxis and had at least one anti-Xa from May 1, 2011 to December 15, 2012 were included. Patients with subprophylactic anti-Xa received increased enoxaparin dose per unit protocol with the goal of obtaining a prophylactic anti-Xa (0.2-0.4 U/ml). Sixty-four patients were included in our analysis. The regression equation was used in 33 patients for initial enoxaparin dosing (Eq) whereas 31 patients received traditionally recommended prophylaxis dosing (No-Eq). Groups were comparable in sex, age, weight, inhalation injury, and burn size. Initial enoxaparin dosing in Eq was significantly more likely to reach target than in No-Eq (73 vs 32%; P = .002). No episodes of hemorrhage, thrombocytopenia, or heparin sensitivity were documented in either group. Median final enoxaparin dose required to reach prophylactic level was 40 mg every 12 hours (range, 30-80 mg). Twenty-one No-Eq patients ultimately reached target, and 11 of these final doses were equivalent to or greater than the predicted equation. Ten patients never reached prophylactic anti-Xa before enoxaparin was discontinued (nine from No-Eq). Two patients, one from each group, developed VTE complications despite appropriate anti-Xa for prophylaxis. A strong correlation was shown between weight, burn size, and enoxaparin dose (r = .68; P < .001). Use of the enoxaparin dosing algorithm significantly increased the frequency of obtaining a target initial anti-Xa. There were no bleeding complications. Enoxaparin dosing correlates to burn size and weight, making a standard dose inappropriate because patient habitus and extent of burn injury are highly variable. This simple equation improves enoxaparin dosing for acute adult burn patients.

Previous work from the authors' group showed a risk for inadequate enoxaparin dosing for venous thromboembolism prophylaxis in adult burn patients when traditional recommendations are used. The purpose of this study was to determine whether this also applied to pediatric burn patients. Included patients were acutely burned, aged 14 years or under, and admitted to the authors' regional burn center between October 1, 2004 and December 15, 2012. Thirty-five patients included in this analysis received enoxaparin for venous thromboembolism prophylaxis dosed initially at 0.5 mg/kg and monitored with anti-factor Xa levels (anti-Xa) between 0.2 and 0.4U/ml. Of the included patients, 80% were male with a median age of 8 years, a median TBSA of 16%, and a median length of stay of 23 days. Initially 21 patients (60%) had an undetectable anti-Xa (<0.2 U/ml). Enoxaparin doses were increased but 18 patients (51%) never achieved target anti-Xa. There were no significant differences in sex, weight, dose, depth of injury, or body mass index between those who received appropriate prophylaxis and those who were undertreated. However, median size of burn was significantly larger, median age and height were significantly lower in those who did not reach target. The low number of patients achieving target prophylactic anti-Xa in this study demonstrates the need for routine anti-Xa monitoring in pediatric burns. Additionally, pediatric patients with major burn injury may require initial dosing of enoxaparin greater than published recommendations because of altered pharmacokinetics.

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.

Altered pharmacokinetics in critically ill patients have been shown to result in inadequate enoxaparin dosing for venous thromboembolism (VTE) prophylaxis. In the burn unit, routine monitoring of antifactor Xa levels was implemented to ensure adequate VTE prophylaxis. The purpose of this study was to examine the appropriateness of enoxaparin dosing for VTE prophylaxis in this specialized patient population. The authors reviewed patients with acute burn injury from June 1, 2009, to October 20, 2009, who had enoxaparin therapy monitored with antifactor Xa levels. Data collection occurred prospectively. Thirty-eight patients received enoxaparin subcutaneously for prophylaxis of VTE and had antifactor Xa levels measured. Thirty (79%) patients had initial antifactor Xa levels less than 0.2 U/ml. Enoxaparin dosages were subsequently increased as needed to achieve antifactor Xa levels of 0.2 to 0.4 U/ml. Eight of 38 patients never achieved goal antifactor Xa level before enoxaparin was discontinued. The median final dose required to achieve an antifactor Xa level within therapeutic range was 50 mg every 12 hours (range 30-70 mg). In linear regression, final enoxaparin dose correlated with TBSA. Two patients had clinically significant thromboembolic events. There were no documented episodes of significant hemorrhage, thrombocytopenia, or heparin-associated allergy. The low antifactor Xa levels observed in this study demonstrate that standard dosing of enoxaparin for VTE prophylaxis is inadequate for patients with acute burns. In these patients, both a higher initial enoxaparin dose and routine monitoring of antifactor Xa levels are recommended.