A patient on chronic warfarin therapy is nil per os (NPO) in the hospital; how should I manage anticoagulation?

Management of Anticoagulation in NPO Hospitalized Patients on Warfarin

Continue warfarin at the patient's usual home dose even when NPO, as warfarin is absorbed systemically and does not require oral intake for effectiveness. 1

Key Management Principles

Continue Warfarin During NPO Status

• Warfarin should NOT be held simply because a patient is NPO 1
• The anticoagulant effect of warfarin persists beyond 24 hours and does not depend on concurrent food intake 1
• Warfarin tablets can be administered with small sips of water even in NPO patients, or crushed and given via nasogastric/feeding tubes if necessary 1

Monitor INR Closely

• Check INR daily or every other day during acute hospitalization when patients are NPO, as illness, medications, and nutritional status changes can affect warfarin metabolism 1
• Maintain therapeutic INR in the target range (typically 2.0-3.0 for most indications) 1
• Additional PT/INR testing is recommended when other medications are initiated, discontinued, or taken irregularly during hospitalization 1

When to Consider Bridging with Heparin

High Thromboembolic Risk Patients Requiring Procedure

Bridging anticoagulation with LMWH or unfractionated heparin is only indicated if warfarin must be interrupted for a procedure in high-risk patients 2

• Stop warfarin 5-6 days before the procedure 2
• Start therapeutic-dose LMWH 3 days before the procedure 2
• Give last preprocedural LMWH dose at least 24 hours before surgery at half the total daily dose 2

High-Risk Conditions for Thromboembolism (requiring bridging):

• Mechanical heart valves (especially mitral position or older valve types) 2
• Atrial fibrillation with CHADS2 score ≥5 or recent stroke/TIA (within 3 months) 2
• Recent venous thromboembolism (within 3 months) 2

Common Pitfalls to Avoid

• Do NOT automatically hold warfarin in NPO patients - this is the most common error and unnecessarily increases thrombotic risk 1
• Do NOT use bridging therapy routinely - it is only for high-risk patients undergoing procedures, not for simple NPO status 2
• Do NOT assume missed nutrition affects warfarin immediately - the anticoagulant effect is delayed and prolonged, with a half-life allowing once-daily dosing 1
• Do NOT forget to check for drug interactions - hospitalized patients often receive new medications that can significantly alter INR 1

Special Considerations for Procedures

If Procedure is NOT Planned

• Continue warfarin at home dose 1
• Monitor INR every 1-2 days during acute illness 1
• Adjust dose based on INR results, not NPO status 1

If Elective Procedure is Planned

For low bleeding-risk procedures (dental work, cataract surgery, minor dermatologic procedures):

• Continue warfarin with INR at low end of therapeutic range 2, 1
• No bridging needed 2

For high bleeding-risk procedures (major surgery, neuraxial anesthesia):

• Stop warfarin 5-6 days before procedure 2
• Check INR before procedure; proceed if INR ≤1.5 2
• Consider bridging only in high thromboembolic risk patients 2
• Resume warfarin evening of or morning after procedure 2

Resumption After Procedure

• Resume maintenance dose of warfarin on the evening of or morning after the procedure 2
• For high bleeding-risk surgery, delay LMWH restart for 48-72 hours but resume warfarin earlier 2
• For low bleeding-risk surgery, restart LMWH at previous dose within 24 hours 2
• Continue LMWH until INR >1.9, typically requiring 4-5 days of overlap 2, 1