Postoperative epidural analgesia and oral anticoagulant therapy

The relative safety of epidural catheter placement with subsequent heparinization has been well documented. However, what is the risk of neurologic sequelae in such patients who receive warfarin perioperatively? This study retrospectively evaluates the risk of spinal hematoma in patients receiving postoperative epidural analgesia while receiving low-dose warfarin after total knee replacement. All patients received low-dose warfarin to prolong the prothrombin time (PT) to 15.0-17.3 s (normal 10.9-12.8 s). There were 192 epidural catheters placed in 188 patients. All catheters were advanced through an 18-gauge needle. In 13 instances, blood was noted during needle and/or catheter placement. In addition to warfarin, 36 patients with indwelling catheters received nonsteroidal antiinflammatory drugs (NSAIDs). Epidural catheters were left indwelling 37.5 +/- 15 h (range 13-96 h). The mean PT was not increased beyond the normal range until the third postoperative day and did not reach 15 s until the seventh postoperative day. Cumulative warfarin dose at that time was 20.0 +/- 7.6 mg. Mean PT at the time of epidural catheter removal was 13.4 +/- 2 s. There were no signs of spinal hematoma. Although epidural catheter placement and subsequent anticoagulation with warfarin appears relatively safe, there is a large variability in patient response to warfarin; therefore, coagulation status should be monitored to avoid excessive prolongation of the PT, and the patient should be watched closely for evidence of spinal hematoma.