Anticoagulant protocols

Full dose bridging is the most widely used perioperative management for patients with a high risk of thrombosis, however several studies have evaluated protocols with a lower dose of low molecular weight heparin, somewhere between full dose treatment and a prophylactic dose. Malato et al1 gave high risk patients a fixed dose, twice the prophylactic dose, whereas Pengo et al2 used a LMW heparin dose based on weight at approximately 80% of the full treatment dose. We have adopted this as the "Low Dose" protocol in this application.

The ACCP guidelines do not provide clear guidance on which protocol to use. In most series the prophylactic dose protocol has only been used in low or intermediate thrombosis risk patients. Therefore in this protocol we are proposing to use standard dose bridging or low dose bridging (80% full dose) for high risk patients depending on the bleeding risk. For intermediate risk patients we are offering standard dose, low dose and prophylactic dose protocols as options again based on the bleeding risk.

The Australasian Guidelines include an additional protocol using a single dose of intravenous vitamin K given 12 to 18 hours before surgery. This should only be used in patients with stable INR control over the preceeding 2 to 4 weeks. A prospective study showed that this approach could achieve a preoperative INR <1.5 in 94% of patients with few episodes of major bleeding and low rates of warfarin resistance on restarting warfarin3.

For patients with a low risk of thrombosis the guidelines recommend that warfarin can be stopped safely during surgery.

  1. Malato et al. Patients requiring interruption of long-term oral anticoagulant therapy: the use of fixed subtherapeutic dose of low-molecular-weight-heparin. J Thromb Haemostas. 2005;8:107-113.
  2. Pengo et al. Italian Federation of centers for the Diagnosis of Thrombosis and Management of Thrombotic Therapies (FCSA). Standardised low molecular weight heaprin bridging regimen in outpatients on oral anticoagulants undergoing invasive procedures or surgery. Circulation 2009;119:2920-27.
  3. Burbury KL, Milner A, Snooks B et al. Short-term warfarin reversal for elective surgery using low-dose intravenous vitamin K: safe, reliable and convenient Br J Haematol 2011;154:626-634.