P116\u2005Prophylactic use of enoxaparin during bariatric surgery in adolescents with severe obesity

Abstract

Background Severe obesity predisposes adults and youth to a higher risk of venous thromboembolism (VTE). Enoxaparin is frequently used for their VTE management. This study evaluates a BMI-stratified prophylactic dosing regimen of enoxaparin in severely obese adolescents undergoing bariatric surgery. Methods This prospective study enrolled severely obese adolescents aged 12–20 years undergoing laparoscopic sleeve gastrectomy. Prophylactic enoxaparin was dosed at 40 mg SC (for a BMI less than 50 kg/m2) and 60 mg SC (for a BMI equal to or greater than or 50 kg/m2). Blood samples were drawn until 12 hrs post-dose. Plasma Anti-Factor Xa (Anti-FXa) activity was used as a surrogate marker for enoxaparin plasma concentration and pharmacokinetics were assessed using non-compartmental PK analysis. The primary efficacy outcome was the anti-FXa activity 4–6 hours after dosing, and the primary endpoint was the proportion of patients who reached prophylactic anti-FXa activity of 0.1–0.3 U/mL between 4–6 hours after dosing. Results Ten female and two male obese adolescents (age range 14–19 years) had a mean body weight of 140.8 kg (93.7–174 kg) and a mean BMI of 49.9 kg/m2 (38.4–58 kg/m2). Four patients received 40 mg enoxaparin, 8 patients were dosed with 60 mg enoxaparin. No VTE or major bleeding occurred. Peak plasma anti-FXa activity (Cmax) ranged from 0.14–0.30 IU/mL (median Cmax 0.205 IU/mL). Median Tmax was 5.67 hours (range 3.78–7.52 hours). Median AUCi was 1.00 h*IU/mL (range 0.42–1.67 h*IU/mL). 10 out of 12 patients (83%) reached the primary endpoint with anti-FXa activity in the range for VTE prevention (0.1–0.3 IU/mL). Conclusions In this single center cohort study, the dosing scheme of 40 mg vs 60 mg enoxaparin stratified according to BMI proved to be effective in reaching prophylactic anti-FXa activity in 83% of adolescent patients. This dosing scheme is in accordance with current practice in adults. Disclosure(s) J. Vaughns and J. van den Anker are supported by the Eunice Kennedy Shriver National Institute of Child Health and Development (5T32HD087969).