Safe epidural catheter removal in the patient receiving warfarin: does anybody really know what (prothrombin) time it is?

摘要

We read with interest the study by Benzon et al. regarding international normalized ratio (INR) levels, epidural catheter removal, and guidelines developed by the American Society of Regional Anesthesia and Pain Medicine (ASRA). In summary, the authors evaluated the factor VII activities and INR in 121 patients during the initiation of warfarin therapy. Warfarin therapy was started the night of surgery; no additional antiplatelet or anticoagulants, including low-molecular-weight heparin, were administered. The authors reported that on postoperative day (POD) 1,11 patients had prothrombin times greater than the 1.4 level recommended by ASRA for removal of an epidural catheter. In 8 of these 11 patients, despite an increased INR, the factor VII activity levels were within the normal range. In the remaining 3 patients, the factor activities were 45%, 24%, and 22%, corresponding to INRs of 1.5, 1.5, and 1.8. Based on these results, Benzon and coworkers concluded that, for patients receiving epidural analgesia and warfarin for deep vein thrombosis prophylaxis, there is "no evidence that epidural catheters should not be removed even with INRs up to 1.9."