These guidelines are based directly on the Australasian Society of Thrombosis and Haemostasis guidelines. Additional published guidelines include those produced by the British Society for Haematology and the American College of Chest physicians
Starting warfarin
The present view is that warfarin treatment should be introduced slowly at a low dose . This may take longer to achieve stable control but is potentially safer as the risk of bleeding is less. Studies have shown that in practice there is little difference in the time to reach stability using a daily dose of 5mg. It may be appropriate to start older patients on 3mg daily especially when commencing warfarin for prophylaxis in atrial fibrillation.
Combining treatment with low molecular weight heparin
Combined therapy is only necessary when you wish to achieve rapid anticoagulation for example in the treatment of deep vein thrombosis and pulmonary embolus. At least 5 days of LMW Heparin should be given at the start of treatment as it takes this long for warfarin to achieve its full anticoagulant effect.
Managing overdose
It is important that patients with bleeding are managed urgently. We offer separate protocols for managing a high INR depending on the risk of bleeding. In these situations it is important to assess the patient’s need for ongoing warfarin therapy. In a patient with poor control and frequent high results it may be safer to stop warfarin if treatment is not essential.
Surgery
The management around the time of surgery can be difficult. Much of the advice is based on expert opinion as few studies have examined this. We recommend that you carry out an assessment of the risk of bleeding and the risk of thrombosis and base your treatment plan on this.