NB: For anticoagulation and neuraxial anesthesia, please see the chapter 119 on safety in regional anesthesia.
- VKAs block the carboxylation of factors II, VII, IX, and X as well as proteins C and S (coagulation inhibitors)
- Equilibrium is reached only after about 5 days as factors have different half-lives
- Initial hypercoagulable state as protein C has the shortest half-life
Table 12-1 Indications and Therapeutic Targets of VKAs |Favorite Table|Download (.pdf)
Table 12-1 Indications and Therapeutic Targets of VKAs
|Indications for target INR of 2.5; range 2–3||Indications for target INR of 3; range 2.5–3.5|
- Atrial fibrillation (AF)
- Rheumatic mitral valve disease and AF or a history of previous systemic embolism
- St. Jude Medical aortic bileaflet valve
- Bioprosthetic valves: VKA for first 3 months after aortic or mitral valve insertion
- AF and a recent CVA or TIA
- Tilting disk valves and bileaflet mechanical valves in the mitral position
- Caged ball or caged disk valves; give VKA in combination with aspirin, 75–100 mg/day
The following procedures do not warrant VKA discontinuation if INR 2–3:
- Cataract surgery without retrobulbar block
- EGD without biopsy, colonoscopy without biopsy/polypectomy, ERCP without sphincterotomy
- Minor dental procedures
- Joint and soft tissue injections and arthrocentesis
For AF, assess thromboembolic risk based on the CHADS2 score (0–6 points).
Table 12-2 CHADS2 Score for Assessment of Thromboembolic Risk |Favorite Table|Download (.pdf)
Table 12-2 CHADS2 Score for Assessment of Thromboembolic Risk
|Age >75 years||1 point|
|History of stroke||2 points|
- 0 points: no indication for chronic anticoagulation; discontinue warfarin 5 days before surgery; do not resume unless other indication
- 1–2 points: discontinue warfarin 5 days before surgery; resume 5 days after surgery
- 3 points or more: discontinue warfarin 5 days before surgery; LMWH, or IV UFH relay
- Discontinue warfarin at least 5 days before elective procedure, or longer if INR >3.0
- Assess INR 1–2 days before surgery; if INR >1.5, consider 1–2 mg of oral vitamin K
- Reversal for urgent surgery: consider 2.5–5 mg of oral or intravenous vitamin K
- Immediate reversal for emergent surgery: consider fresh frozen plasma, prothrombin complex concentrate, or recombinant factor VIIa
Patients at high risk for thromboembolism:
- For patients who have a mechanical valve, high risk includes those who have mitral valve prostheses, older aortic valve prostheses, or had a CVA or TIA in the past 6 months
- For patients who have atrial fibrillation, high risk includes a CHADS2 score of 5–6, a CVA or TIA within the past 3 months, or rheumatic valvular heart disease
- For patients who had a venous thromboembolism (VTE), high risk includes a VTE within the past 3 months, ...
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessAnesthesiology Full Site: One-Year Subscription
Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more
Pay Per View: Timed Access to all of AccessAnesthesiology
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.