Warfarin Management for Spine Epidural and Hip Injections
This elderly female with a mechanical aortic valve replacement should stop warfarin 5 days before both the spine epidural and hip injections, verify INR ≤1.5 on the day before or morning of the procedures, and will require bridging anticoagulation with LMWH given her high thromboembolic risk from the mechanical valve. 1
Pre-Procedure Warfarin Interruption
Timing of Warfarin Discontinuation
Stop warfarin 5 days (withholding 5 doses) before the procedures to allow INR to decrease to ≤1.5, which is the required target for neuraxial procedures like spine epidurals 1
For elderly patients specifically, a longer interruption period may be necessary beyond the standard 5 days, as older adults have slower INR normalization 1
Check INR on the day before or morning of the procedure to confirm it is ≤1.5 before proceeding 1, 2
If INR remains elevated (1.5-1.8) one day before the procedure, administer low-dose oral vitamin K (1-2.5 mg) for reversal 1
Bridging Anticoagulation Strategy
High Thromboembolic Risk Classification
This patient falls into the high-risk category due to mechanical aortic valve replacement, requiring bridging anticoagulation 1
Mechanical heart valves carry substantial thrombotic risk that necessitates bridging therapy when warfarin is interrupted 1
Bridging Protocol
Start LMWH at therapeutic dose 36 hours after the last warfarin dose (approximately 3 days before the procedures) 1
Administer the last pre-procedure LMWH dose 24 hours before the procedures at half the normal daily dose to minimize residual anticoagulant effect 1
Therapeutic LMWH dosing includes: enoxaparin 1.5 mg/kg once daily or 1.0 mg/kg twice daily subcutaneously; dalteparin 200 IU/kg once daily or 100 IU/kg twice daily subcutaneously 1
Post-Procedure Management
Warfarin Resumption
Resume warfarin at the usual maintenance dose on the evening of or morning after the procedures once adequate hemostasis is achieved 1
Do not use loading doses (doubling the maintenance dose), as this adds complexity without proven benefit 1
Post-Procedure Bridging for High-Bleed Risk Procedures
For spine epidural injections (high bleeding risk with catastrophic consequences), wait 48-72 hours before restarting LMWH at therapeutic dose 1
Consider a stepwise approach: start with prophylactic-dose LMWH in the first 24-48 hours, then increase to therapeutic dose 1
Continue LMWH bridging until INR has been therapeutic (≥2.0) for at least 2 consecutive measurements taken more than 24 hours apart 1
Check INR on postoperative day 4 and discontinue LMWH if INR >1.9 1
Critical Pitfalls to Avoid
Common Errors
Do not assume 5 days is always sufficient without INR verification, as approximately 7% of patients still have INR >1.5 after 5 days of warfarin discontinuation 2
Do not restart full-dose LMWH too early post-procedure, as this causes major bleeding in up to 20% of patients undergoing high-bleed risk procedures 1, 2
Do not give routine vitamin K for INR 1.5-1.9 measured 1-2 days before surgery, as this causes post-operative warfarin resistance without proven benefit 3, 4, 2
Do not use high-dose vitamin K (>2.5 mg) for routine reversal, as this creates difficulty with re-anticoagulation 4
Special Considerations for Neuraxial Procedures
Neuraxial anesthesia (spine epidural) carries catastrophic bleeding risk if performed with inadequate anticoagulation reversal, making INR verification mandatory 1, 2
The combination of high thromboembolic risk (mechanical valve) and high bleeding risk (neuraxial procedure) requires meticulous timing of both warfarin interruption and LMWH bridging 1
Monitoring Strategy
More frequent INR monitoring is required in elderly patients due to higher bleeding risk and more fluctuations in INR 1, 3
Monitor INR daily until stable, then 2-3 times weekly for 1-2 weeks, then weekly for 1 month after resuming warfarin 1
Identify and address underlying causes of INR variability including medication interactions, dietary changes, and illness 3