Prevention of thromboembolism after spinal cord injury

Thromboembolism is a major cause of morbidity and mortality in patients with spinal cord injury. The prevalence of DVT approaches 100%, and 1 to 2% will die of PE. Following injury, there is hypercoagulability as reflected by an increase in von Willebrand factor activity and antigen, and increased platelet reactivity to collagen. Thrombosis usually occurs 1 to 3 weeks after injury, with a peak between days 7 and 9. Intermittent calf compression boots reduce the frequency of thrombosis to 40%, and the addition of aspirin, 300 mg twice daily, and dipyridamole, 75 mg thrice daily, decrease this further to 25%. In an attempt to provide more effective prophylaxis, a further trial was conducted using heparin. Twenty-nine patients were randomized to receive 5000 U subcutaneously every 12 hours and compared with an equal number of patients treated with doses of heparin adjusted to prolong the APTT to 1.5 times control values; the mean dose was 13,200 U every 12 hours. Thromboembolism occurred in 9 (31%) of those on the fixed dose (6 VDT and 3 PE) and only 2 (7%) on the adjusted dose (p < 0.05); however, 7 (24%) of the patients receiving the higher doses of heparin had bleeding compared with none of those on the fixed dose (p < 0.02). Most recently, we have compared the safety and effectiveness of a low molecular weight heparin (Logiparin, Novo) with standard heparin. The former was given once daily in a dose of 3500 anti-Xa units, and the latter was 5000 U every 8 hours, both given subcutaneously. No thrombosis or bleeding occurred in 20 Logiparin-treated patients, whereas 5 of 21 receiving standard heparin had thrombosis, including two with fatal PE, and two additional patients had bleeding. This difference in event rate between the two treatments was statistically significant (p < 0.02). We conclude that thromboprophylaxis with a low molecular weight heparin (Logiparin) offers great promise in the management of patients with spinal cord injury.