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SMDC Vitamin K-Warfarin Reversal Guidelines
For
Overanticoagulation, Bleeding, and Emergent Invasive Procedures
I.
Caveats (specific recommendations start on page 2)
General
 Remember that patients receive anticoagulation to prevent life-threatening thrombosis.
 Consider the patient’s future anticoagulation needs when planning the reversal of warfarin anticoagulation.
Vitamin K
 The effect of vitamin K on reversing warfarin anticoagulation is delayed, reaching its full effect at about 24
hours.
 Excessively large doses of vitamin K do not reverse anticoagulation faster and may cause weeks of warfarin
resistance. Any dose of vitamin K greater than 10 mg should be considered excessive.
 Oral vitamin K is the preferred preparation to be used in most situations.
 Oral vitamin K is more predictable in its bioavailability and has a quicker onset of action than subcutaneous
vitamin K; it also offers additional convenience and safety in comparison to other dosage forms.
 Intramuscular vitamin K will not be used per SMDC policy to avoid hematoma risk.
 Intravenous vitamin K has a more predictable response and faster onset of action than other forms of
vitamin K. However, IV vitamin K may cause anaphylaxis, and slow infusion rates have never been proven to
prevent anaphylaxis. It should be diluted in 50 mL and given via piggyback infusion over at least 30
minutes. It is the preferred route of administration for severe bleeding situations.
 Subcutaneous vitamin K is not as effective on a mg-to-mg basis as IV vitamin K and does not work as
quickly; but it does not carry the anaphylaxis risk of IV vitamin K. It is an alternative when a patient cannot
take oral vitamin K and the situation is not emergent.
Fresh Frozen Plasma (FFP)
 FFP is a blood product containing a concentration of clotting factors. All of the risks of blood product
transfusions apply to FFP.
 FFP replaces depleted clotting factors and is therefore the fastest way to reverse warfarin anticoagulation. It
begins to work immediately with a full effect in 6 hours.
 FFP is usually given in doses of 2 to 4 units and is repeated every 6 to 12 hours as needed. 4 units should
be used in a severe bleeding situation.
Vitkrecs8.doc
II. Management of overanticoagulation in patients without bleeding
INR above target but less than 5
Lower the dose or omit the dose, monitor more frequently, and resume therapy at a lower dose
when the INR is at a therapeutic level.
INR 5 to 9
Low Thrombotic Risk2
High Thrombotic Risk3
1
No risk factors for bleeding
Omit the next 1 to 2 doses of Omit the next 1 to 2 doses of
warfarin.
warfarin.
Risk factors for bleeding present1
Hold warfarin, give 1 to 2.5
Omit the next 1 to 2 doses of
mg oral vitamin K.
warfarin and monitor closely
for bleeding OR hold
warfarin, give 1 to 2.5 mg
oral vitamin K.
INR greater than 9
Low Thrombotic Risk2
High Thrombotic Risk3
1
No risk factors for bleeding
Hold warfarin, give 5 mg oral Hold warfarin, give 5 mg oral
vitamin K
vitamin K
Risk factors for bleeding present1
Hold warfarin, give 10 mg
Hold warfarin, give 5 to 10
oral vitamin K
mg oral vitamin K
In all above cases, monitor more frequently and resume therapy at a lower dose when the INR
is at a therapeutic level if a reversible reason for the elevation cannot be identified
1. Risk factors for bleeding: History of GI bleed (not peptic ulcer disease WITHOUT bleeding),
hypertension, cerebrovascular disease, ischemic stroke, congestive heart failure, renal
insufficiency, concurrent aspirin, age greater than 75 years, and recent major surgery.
2. Low
Atrial fibrillation WITHOUT:
thrombotic
 history of severe left ventricular dysfunction (ejection fraction less than
risk:
25%)
 clinically significant rheumatic heart disease
 previous thromboembolic events within 6 months
 cardioversion in the last month
 bioprosthetic heart valve
 severe left atrial enlargement
More than 1 month since arterial thromboembolism
Deep vein thrombosis prophylaxis
More than 3 months since deep vein thrombosis or pulmonary embolism
3. High
Atrial fibrillation WITH:
thrombotic
 history of severe left ventricular dysfunction (ejection fraction less than
risk:
25%)
 clinically significant rheumatic heart disease
 previous thromboembolic events within 6 months
 cardioversion in the last month
 bioprosthetic heart valve
 severe left atrial enlargement
Less than 1 month since arterial thromboembolism
Mechanical heart valves
Less than 3 months since deep vein thrombosis or pulmonary embolism
III.
Management of anticoagulated patients with bleeding
Minor bleeding:
 INR is low or in target range: make no changes and observe carefully
 INR above target but less than 5 (high): adjust warfarin appropriately, no vitamin K
 INR 5 to 9 (very high): hold warfarin, give 1 to 2.5 mg oral vitamin K
 INR greater than 9 (critical high): hold warfarin, give 5 to 10 mg oral vitamin K
Major bleeding:
 Any INR: clinical circumstances such as the severity of bleeding, risk of thrombosis, and the INR
value will dictate the course of action. Generally in this situation the advice would be to hold warfarin,
give 4 units FFP, and supplement FFP with 10 mg vitamin K by slow piggyback IV infusion over at
least 30 minutes
Vitkrecs8.doc
In all above cases, monitor more frequently and resume therapy at a lower dose when the INR is at a
therapeutic level if a reversible reason for the elevation cannot be identified.
Minor bleeding example: bleeding gums
Major bleeding example: major GI bleed, CNS bleed, retroperitoneal bleed, etc.
IV.
Management of anticoagulated patients for emergent invasive procedures
Important facts to remember:
1. The peak effect of vitamin K on reversing warfarin anticoagulation takes 24 hours, although you may start
to see effects in 6 to 12 hours.
2. FFP replaces depleted clotting factors and is therefore the fastest way to reverse warfarin
anticoagulation. It begins to work immediately, with a full effect in 6 hours.
Low surgical risk of bleeding:
Goal is low therapeutic INR (INR= 2 to 2.5)
 INR above target but less than 5: hold warfarin, consider giving 2.5 mg oral vitamin K, consider giving
FFP
 INR 5 to 9 (very high): hold warfarin, give 2.5 mg oral vitamin K, consider giving FFP
 INR greater than 9 (critical high): hold warfarin, give 5 mg oral vitamin K, consider giving FFP
In all cases, recheck INR in 12 hours and re-administer vitamin K and/or FFP if needed.
Moderate surgical risk of bleeding:
Goal is subtherapeutic INR (INR 1.5)
 INR above 1.5 but less than upper target range: hold warfarin, give 2.5 mg oral vitamin K, consider
giving FFP
 INR above target but less than 5: hold warfarin, give 2.5 mg oral vitamin K and FFP
 INR 5 to 9 (very high): hold warfarin, give 5 to 10 mg oral vitamin K and FFP
 INR greater than 9 (critical high): hold warfarin, give 10 mg oral vitamin K and FFP
In all cases, recheck INR in 12 hours and re-administer vitamin K and/or FFP if needed.
High surgical risk of bleeding:
Goal is complete reversal of anticoagulation (INR=1)
 Hold warfarin, give FFP and 10 mg oral vitamin K
In all cases, recheck INR in 12 hours and re-administer vitamin K and/or FFP if needed.
Refer to the SMDC bridging guidelines for appropriate management of emergent invasive procedure
patients post-op.
Low surgical risk of bleeding example: accessible laceration of the arm.
Moderate surgical risk of bleeding example: major abdominal surgery (bowel resection).
High surgical risk of bleeding example: brain surgery.
References:
Ansell J, Hirsh J, Poller L, et al. The pharmacology and management of the vitamin K antagonists. CHEST 2004;
126;204S-233S.
Crowther MA, Douketis JD, Schnurr T, et al. Oral vitamin K lowers the international normalized ratio more rapidly than
subcutaneous vitamin K in the treatment of warfarin-associated coagulopathy. Ann Intern Med 2002; 137:251-254.
Whitling AM, Bussey HI, Lyons RM. Comparing different routes and doses of phytonadione for reversing excessive
anticoagulation. Arch Intern Med 1998; 158:2136-2140.
Vitkrecs8.doc