Warfarin over anticoagulation resident survival guide
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]
Overview
There are several protocols to follow when attempting to correct the effects of over-anticoagulation with warfarin. Generally, the most important initial step is to stop the warfarin, and to continue to check the INR for its return to therapeutic levels. The additional steps are dependent upon the value of the INR, whether the patient is at a high risk of bleeding, and whether they are actively bleeding. Actively bleeding patients who have a supratherapeutic INR level will require more aggressive measures to prevent complications or death.
Treatment of Over-anticoagulation of Warfarin
Supratherapeutic INR Without Bleeding
INR less than 5
- Decrease dose or hold warfarin.
- Recheck INR in 24 hrs.
- Restart warfarin at a decreased dose when INR is within target therapeutic range.
INR 5 to 9
- Follow the same steps as above (algorithm of INR less than 5).
- An alternative option is to hold 1-2 doses of warfarin and give vitamin K 2.5 mg PO in high risk patients.
- Patients who have a high risk of bleeding, or who are undergoing surgery, should be given vitamin K 2.5 mg PO or a 5 mg PO.
INR > 9
- Follow the same steps as above (algorithm of INR 5-9).
- Can repeat Vitamin K in 24 hours if necessary.
Supratherapeutic INR with Bleeding
- Discontinue warfarin.
- Vitamin K IVPB (IV piggyback) 10 mg in NS 50 ml over 30 minutes.
- FFP or Profilnine SD (Prothrombin complex concentrate) or recombinant factor VII a (Novoseven).
- Check INR 12 hours after Vitamin K.
- Can repeat vitamin K every 12 hours for persistently elevated INR.
Therapeutic Options
Vitamin K
- Oral vitamin K tablets are available. The lowest dose is 2.5 mg.
- The oral route preferred over subcutaneous route due to its high efficacy.
- Vitamin K should never be given via intramuscular route or IV push.
- If IV route is necessary it should be IV piggyback.
Fresh Frozen Plasma
- Dose = 15 ml/kg
- If INR is therapeutic, a dose of 5-8 ml/kg is sufficient.
Prothrombin Complex Concentrate
- Used in addition to FFP.
- Dose = 25-50 units/kg
Recombinant Factor VIIa (Novoseven)
- Used in addition to FFP
- Dose = 40 mcg/kg