Venous thromboembolism: treatment strategiesBMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7370.948 (Published 26 October 2002) Cite this as: BMJ 2002;325:948
- Alexander G G Turpie,
- Bernard S P Chin,
- Gregory Y H Lip.
Pulmonary embolism and deep vein thrombosis are treated using similar drugs and physical methods. The efficacy of intravenous infusion of unfractionated heparin was first proved in a randomised trial in 1960. Subsequently, trials concentrated on the dose, duration of infusion, mode of administration, and combination with warfarin treatment. Later trials have reported the efficacy and cost effectiveness of low molecular weight heparin compared with unfractionated heparin.
Unfractionated heparin, administered by continuous infusion or subcutaneous injections adjustedto achieve activated partial thromboplastin time (APTT) greater than 1.5, is effective as initial treatment of venous thromboembolism. Initial heparinisation should be followed by long term anticoagulation with oral anticoagulants. APTT is a global coagulation test and not specific for heparin, and it is also influenced by various plasma proteins and clotting factors.Measuring plasma heparin levels is more accurate but it is impractical and expensive. A sensible approach is to standardise the APTT with plasma heparin within each laboratory.
Antithrombotic treatment is often inadequate in the first few days, predisposing to recurrences. Anticoagulation with warfarin after discharge should continue for at least three months, possibly six months. Low molecular weight heparin is as efficacious as unfractionated heparin in prophylaxis and treatment
The most common mistake when starting heparin treatment is failure to achieve adequate anticoagulation. APTT ratios of less than 1.5 during the first few days of heparin therapy increase the long term risk of venous thromboembolism recurrence. Hence, the initial bolus dose should be adequate and APTT monitored every six hours during the first 24 hours of heparin infusion.
Initial antithrombotic therapy for deep vein thrombosis with unfractionated heparin
Check baseline APTT, prothrombin time, full blood count
Confirm there are no contraindications to heparin therapy
Intravenous bolus 5000 IU
Continuous unfractionated heparin infusion—Start infusion at 18 IU/kg/hour (~30 000/24 hours in a 70 kg man)