With a patient on oral anticoagulant therapy, some procedures (dental work) may be done without stopping warfarin. In others, with INR in target range 2-3, it is sufficient to stop warfarin 3 days before surgery and restart the usual maintenance dose the evening of the surgery.
In cardiac surgery bridging anticoagulation in the form of heparin is not required for Atrial fibrillation (Af). However, if they have a mechanical heart valve or have a high risk of thrombosis (have a family or personal history of venous thromboembolism (VTE), or over 60 years of age having a high risk procedure) this period should be covered by heparin. Having stopped warfarin, if the INR pre-op is over 2.5, small amounts of Vitamin K (1-2mg) may be given.
For rapid reversal parenteral administration of 5-10 mg of vitamin K restores hepatic vitamin K levels and permits normal production of coagulation proteins within 6 to 10 hours.
For less aggressive reversal, (such as reducing the INR in patients who have a high INR (over 8) or pre-surgery and INR over 2.0, Vitamin K 2-4mg may be given orally.
For urgent reversal in life threatening haemorrhage, Prothrombin Complex Concentrates (PCC, containing factors II, VII, IX and X) at 50 units per kg are preferred to FFP. FFP (15ml/kg) should only be used in the absence of PCC.
For further information see:
BCSH Guidelines on oral anticoagulation (warfarin): third edition 1998 (www.bcshguidelines.com)
BCSH Guidelines for the use of Fresh Frozen Plasma, Cryoprecipitate and Cryosupernatant, British Journal of Haematology 2004; 126, 11-28 (www.bcshguidelines.com)
A sample policy on the management of warfarin reversal has been prepared by the Leeds Teaching Hospital NHS Trust and can be downloaded here:
Management of warfarin reversal (rev 2006)
Management of warfarin reversal flowchart (rev 2006)