Warfarin Dosing and Monitoring

Question 1

How do you dose a patient who just started warfarin?

Answer 1

-Initial dose: 5 mg PO once daily
-Overlap with UFH/LMWH/Xa for at least 5 days AND until INR is therapeutic
-Adjust the weekly dose to achieve INR

Question 2

What is a typical goal INR?

Answer 2

2.0-3.0

Question 3

What is the goal INR for an aortic valve replacement - mechanical On-X

Answer 3

1.5-2.0

Question 4

What is the goal INR for a patient with a mechanical mitral hear valve?

Answer 4

2.5-3.5

Question 5

How often should INR be checked after hospital discharge and warfarin has just been initiated?

Answer 5

-If stable, within 3-5 days
-If unstable, within 1-3 days

Question 6

How often should INR be checked after the first month of therapy?

Answer 6

Weekly

Question 7

When should the INR be checked if the dose was held today?

Answer 7

Within 1-2 days

Question 8

When should the INR be checked if the dose was changed today?

Answer 8

Within 1-2 weeks

Question 9

When should the INR be checked if the dose was changed 2 weeks ago or less?

Answer 9

Within 2-4 weeks

Question 10

When should the INR be checked after a routine follow-up and the patient is stable?

Answer 10

Every 4-6 weeks

Question 11

When should the INR be checked after a routine follow-up and the patient is unstable?

Answer 11

Every 1-2 weeks

Question 12

When should the INR be checked if the patient has been consistently stable for 6 months?

Answer 12

Every 12 weeks

Question 13

When should the INR be checked after a flexible initiation method of warfarin has been initiated?

Answer 13

Daily through day 4, then within 3-5 days

Question 14

When should the INR be checked after an average daily dosing method of warfarin has been initiated?

Answer 14

Within 3-5 days, then within 1 week

Question 15

What are the 5 D’s to ask a patient on warfarin about?

Answer 15

-Drugs (any changes in medications)
-Diseases (any changes in overall medical condition and/or treatment)
-Doses (any missed doses)
-Diet (any changes in diet, specifically green leafy vegetables)
-Drink (any EtOH consumption)

Question 16

What are the two B’s to ask a patient on warfarin about?

Answer 16

-Bruising
-Bleeding

Question 17

How should warfarin dosing be altered when the INR is less than 2?

Answer 17

Increase by 5-15%

Question 18

How should warfarin dosing be altered when the INR is 3.1-3.5?

Answer 18

Decrease by 5-15%

Question 19

How should warfarin dosing be altered when the INR is 3.5-4?

Answer 19

-Hold 0-1 doses
-Decrease by 10-15%

Question 20

How should warfarin dosing be altered when the INR is greater than 4?

Answer 20

-Hold 0-2 doses
-Decrease by 10-15%

Question 21

What does “bridging therapy” mean?

Answer 21

It is when a patient needs to come off of warfarin before a procedure with a high bleeding risk

Question 22

When should you stop warfarin when bridging therapy?

Answer 22

5 days before surgery

Question 23

What should you give instead of warfarin when bridging therapy?

Answer 23

-Give LMWH or UFH until the procedure
-When switching from warfarin to heparin, give a day between the switch with no anticoag treatment

Question 24

When should LMWH be stopped before the procedure?

Answer 24

24 hours before procedure

Question 25

When should IV UFH be stopped before the procedure?

Answer 25

4-6 hours before procedure

Question 26

When can warfarin therapy be resumed after the surgery?

Answer 26

12-24 hours after surgery