Do neonates, infants and young children need a higher dose of enoxaparin in the cardiac intensive care unit?

BACKGROUND: Thromboembolic events are a serious complication occurring in critically ill children admitted to the cardiac intensive care unit. Although enoxaparin is one of the current anticoagulants of choice, dosages in children are extrapolated from adult guidelines. Recent data suggest that this population may need a higher dose than what is currently recommended to achieve target anti-factor Xa levels. The purpose of this study was to evaluate whether children less than 2 years old admitted to the cardiac intensive care unit require a higher enoxaparin dose than that currently recommended to achieve target anti-factor Xa levels.
METHODS: Retrospective chart review including patients who received enoxaparin for the treatment or prophylaxis of venous thrombosis between January, 2005 and October, 2007. Patients were classified as younger and older as well as prophylactic and therapeutic on the basis of age and enoxaparin dose, respectively. Younger patients were those 2 month old or less and older patients were those older than 2 months of age.
RESULTS: A total of 31 patients were identified; 13 (42%) were 2 months or younger and 25 (81%) were postoperative patients. Ten (32%) received prophylactic and 21 (68%) received therapeutic enoxaparin doses. To achieve optimal anti-factor Xa levels, enoxaparin dose was increased in all groups and reached statistical significance in all patients except those older than 2 months who received prophylactic enoxaparin. An average of 2.8 dosage adjustments was needed. No bleeding complications were reported.
CONCLUSIONS: Young children, infants, and neonates admitted to the cardiac intensive care unit required a significantly higher enoxaparin dose than that currently recommended to achieve target anti-factor Xa levels.