Can the Epidural Catheter Be Removed with Warfarin?

1. Can the Epidural Catheter Be Removed with Warfarin? Asokumar Buvanendran, MD, Timothy J. Lubenow, MD Maruti Kari, MD, Jeffrey S. Kroin, PhD Department of Anesthesiology Rush University Medical Center Rush Medical College Chicago, IL

2. For patients undergoing lower limb joint replacement • Post-op epidural analgesia provides improved pain control for Orthopedic patients • Thrombo-prophylaxis (i.e. oral warfarin), • Administered to prevent thromboembolic complications. • Requires several days to attain a therapeutic range (coagulation index INR > 2.00) is attained.

3. Epidural Catheter Removal • ASRA Consensus Guidelines: As thromboprophylaxis with warfarin is initiated, neuraxial cathteters should be removed when the INR is < 1.5. • This is a theoretically avoid spinal epidural venous bleeding that might cause an epidural hematoma. 1 Regional Anesthesia and Pain Med 2003 28:172-197.

4. Epidural Catheter Removal No large studies have examined the post-op incidence of spinal hematoma where epidural catheters are removed at INRs > 1.5 398 patients with INR > 1.5 was studied in 1038 patients1 1 Paravizi et al: Clin Orthopedics 2006

5. Methods: Rush Acute Pain Service policy for Catheter Removal • Not removed until INR levels < 2.0 • On a per case basis, catheters removed at INR levels between 1.80-2.00 if all of the following patient criteria was met: • Completed 2-3 days of post-operative epidural care • Recuperating well • Underwent neurological checks hourly for next 12 h, and every 4 h for next 12 h • No documented severe spinal stenosis

6. Results After IRB approval: Rush’s Acute Pain Service QA Database queried from 1/4/1998 to 6/3/2007. • Subjects: 5140 elective lower limb joint replacement surgery patients with post-op epidural pain management care. (M:2264, F:2876, Age: 63.2 ± 13.3) • APS post-op follow-up: Immediate post-op period to the date of epidural catheter removal. Patients evaluated on the basis of motor, sensory, and neurological status. • Thrombo-prophylaxis: 5 mg warfarin on day of surgery with 2-5 mg given daily thereafter until epidural catheter is removed.

7. Data Collection • Demographic data • Presence/absence of neuro-deficits suggesting epidural venous bleeding and/or hematoma for INR values <1.5, 1.50-1.79, 1.80-2.00, and > 2.00 on the day of epidural catheter removal.

8. Results • No incidence of epidural hematoma and neurologic deficits observed following 5850 procedures (5140 patients, some had 2 surgeries over the 9 years examined). • 4636/5840 (79%) with INR levels < 1.50 at epidural removal • 1214 (21%) had INR levels ≥ 1.5 including • 935 with INR levels of 1.50-1.79 • 218 with INR levels of 1.80-2.00 • 61 with INR levels > 2.00

9. Discussion • The adequacy of INR<1.5 for removal of epidural catheter for patients on warfarin was derived from studies correlating hemostasis with clotting factor levels >40%. • Given the rare incidence of epidural hematoma, multicenter trials with large populations will be needed to provide an evidence-based approach to this clinical conundrum. • Absent such trials, we report the largest series of patients with epidural catheter removal at INR>1.5 and <2.0, with no adverse outcomes observed.