LAUSR

Learning Objectives: Pediatric Intensive Care Unit (PICU) patients are at higher risk for venothromboembolism (VTE) than other hospitalized patients for a variety of reasons. Options for VTE prophylaxis are mechanical or chemical. An often chosen chemical prophylactic agent is enoxaparin, however recommendations for monitoring prophylactic dosing in pediatric populations are lacking. We hypothesize that a significant number of PICU patients on enoxaparin for VTE prophylaxis with the current dosing recommendations have greater than expected anti-factor Xa low molecular weight heparin (LMWH) levels. Methods: Retrospective electronic medical record (EMR) review at our tertiary care children’s hospital from 1/1/2013–7/15/2018. Inclusion criteria: age < 18 years old, intended prophylactic dosing of enoxaparin and at least one correctly-obtained anti-factor Xa LMWH level. Exclusion criteria: preexisting home anticoagulation. Prophylactic dosing: 0.5 mg/kg BID for pediatric patients or 40mg daily for older adolescents. Goal anti-Xa LMWH level defined as < 0.3 units/mL for prophylaxis (per our institution’s practice), 0.5 to 1 units/mL for treatment. Results: 28/177 patients on prophylactic enoxaparin met inclusion criteria during our study period. Average age 13.8 years old (range 4.3–17.9), average PICU length of stay 29.2 days (range 2–151), enoxaparin administration duration 26.8 days (range 1–135). 45 total anti-Xa levels (20 daily dosing, 25 BID dosing). 33/45 (73% of all Xa levels) >0.3 units/mL and of those, 17 (38% of all Xa levels) reached treatment level of anticoagulation and 4 (9% of all levels) reached supratreatment levels (anti-Xa levels >1 unit/mL). No statistically significant difference between dosing groups in number of anti-Xa levels reaching treatment level (7/20 vs 10/25, p=0.77). Conclusions: A clinically significant number of patients receiving enoxaparin for VTE prophylaxis achieve higher than intended levels of anticoagulation. We recommend routine anti-Xa LMWH level monitoring for PICU patients on enoxaparin for VTE prophylaxis. Future directions of our research will seek to determine optimal prophylactic enoxaparin dosing regimens, study the appropriateness of goal anti-Xa LMWH levels of < 0.3 units/mL for VTE prophylaxis, and determine if clinically significant side effects arise from over-dosing enoxaparin.