SAN DIEGO – Administering enoxaparin to patients with acute burn injuries at a dosage of less than 30 mg every 12 hours often leads to subtherapeutic anti-Xa levels that are associated with an increase in risk of venous thromboembolism, according to results from a single-center study.
Dr. Hsin Lin
The finding suggests that enoxaparin dosing should be individualized for this patient population, Hsin Lin, Pharm.D., said in an interview during a poster session at the annual congress of the Society of Critical Care Medicine. "Most of the published enoxaparin dosing regimens we see are not for burn patients," said Dr. Lin, a pharmacist at the University of Utah Burn Trauma Center, Salt Lake City. "Burn patients are hypermetabolic. One dose does not fit everyone."
Dr. Lin and her associates evaluated the effectiveness of a protocol for graduated enoxaparin dosing with concurrent monitoring to achieve a peak anti-Xa level of 0.2-0.4 U/mL in 84 patients with acute burn injuries who received venous thromboembolism (VTE) prophylaxis with an initial dosage of 30 mg subcutaneously twice daily. They adjusted the dosages until patients obtained therapeutic levels or until they were discharged. About 1 month later, the patients were interviewed by telephone to determine if any VTE events had occurred.
The median age of patients was 39 years, their median body mass index was 27 kg/m2, and their injuries covered a median of 15% of body surface area.
Of the 84 patients, 64 showed initial anti-Xa levels below target (0.2 U/mL), and their enoxaparin dosage was then increased. In 15 patients, the target anti-Xa level was never reached before discharge. Of 69 patients who had appropriate anti-Xa levels, 1 had a deep vein thrombosis during the hospital stay, 1 developed pulmonary embolism 1 month after discharge, 2 died of non-VTE causes, and 5 were unable to be reached by telephone.
There were no episodes of abnormal hemorrhage, thrombocytopenia, or heparin allergy documented.
Dr. Lin reported that the median final enoxaparin dosage required to achieve therapeutic anti-Xa levels was 40 mg every 12 hours, ranging from 20 to 70 mg. Linear regression analysis revealed that the final enoxaparin dosage correlated with total body surface area and weight.
"Enoxaparin dose adjustment was associated with a low incidence of VTE events, and there was no hemorrhagic bleeding–related complication," Dr. Lin said. "In patients with acute burn injury, routine monitoring of anti-Xa levels is recommended."
Dr. Lin said that she had no relevant financial disclosures to make.