Use of low molecular weight heparin in preventing thromboembolism in trauma patients.

OBJECTIVE: To investigate the safety and effectiveness of low molecular weight heparin (LMWH) in preventing deep venous thrombosis (DVT) in high-risk trauma patients, compared with mechanical methods of prophylaxis.

DESIGN: A prospective randomized trial conducted over a 19-month period in an urban, academic trauma center.

METHODS: All trauma patients with the following risk factors for the development of DVT were considered for enrollment in this study: any injury with an Abbreviated Injury Scale score > or = 3; major head injury (Glasgow Coma Scale score < or = 8); spine, pelvic, or lower extremity fractures; acute venous injury; or age > 50 years. After a screening venous duplex examination, the patients were assigned to a Heparin versus No-Heparin group, depending upon the presence of injuries precluding the use of heparin. In the Heparin group, the patients were then randomized to receive either LMWH or optimal mechanical compression (defined as bilateral sequential gradient pneumatic compression (SCD) or, in the presence of lower extremity injuries precluding the use of the SCD, the arteriovenous impulse (AVI) compression system). All the patients in the No-Heparin group received optimal compression. Enrolled patients underwent sequential duplex examinations every 5 to 7 days until discharge.

RESULTS: Of the 487 consecutive patients initially enrolled in this study, 372 were available for at least the first two duplex examinations and comprise the study population. Only nine (2.4%) patients developed DVT, compared with the predicted 9.1% rate in high-risk trauma patients receiving no prophylaxis (p = 0.037). Of the 120 patients who were randomized to receive LMWH, only one (0.8%) developed DVT. In the SCD group, there were 5 of 199 patients (2.5%) with DVT, and 3 of 53 (5.7%) in the AVI group. One patient with DVT also had clinical symptoms of pulmonary embolism, but there were no deaths secondary to pulmonary embolism. There was one major bleeding complication potentially associated with the use of LMWH.

CONCLUSIONS: The administration of LMWH is a safe and extremely effective method of preventing DVT in high-risk trauma patients. When heparin is contraindicated, aggressive attempts at mechanical compression are warranted.