Management of venous thromboembolic disease. The impact of low-molecular-weight heparin.

Prophylaxis for DVT unequivocally is beneficial in patients identified to be at high risk. Heparin prophylaxis with subcutaneous low-dose UFH is adequate in some clinical settings but less effective in others. LMWH preparations are effective and safe as prophylaxis in certain medical patients as well as in general surgery and elective hip replacement. Efficacy and safety are demonstrated in the therapy of established venous thromboembolism. Subcutaneous administration of LMWH once or twice daily may prove more convenient from both the patient and nursing viewpoint, particularly in the treatment of established DVT. Monitoring is not necessary when using LMWH preparations as prophylaxis, and a fixed-dose without weight adjustment has been used in most prophylaxis trials. When treating established DVT, less monitoring is likely to be required than currently is the case with UFH. Although the cost of LMWH preparations is greater than that of UFH, the decrease in the occurrence or recurrence of thromboses that has been demonstrated in some trials might prove an effective balance. Future avenues to explore include discovery of better means to standardize the LMWH preparations and determination of the efficacy and safety of LMWH in specific populations, such as those in intensive care units, cancer patients, nursing home patients, and outpatients in general. Although cost-benefit is favorable thus far, meticulous assessment in other settings may enhance the acceptance of these agents. Long-term follow-up could be helpful in determining the relative effect of different heparin preparations on the frequency of postphlebitic syndrome. Comparison of different LMWH fractions may follow, as well as further investigations of newer ultra-low-molecular-weight agents. One LMWH preparation (enoxaparin) already has been approved in the United States for prophylaxis in the setting of elective hip replacement; and dalteparin has been approved here for use as DVT prophylaxis in patients undergoing abdominal surgery when there appears to be a significant risk of thromboembolism. It is likely that LMWH preparations will become even more widely used in North America and that the approved indications will expand to include prophylaxis in numerous settings and the treatment of established venous thromboembolism.