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Today we will finish our discussion with a very controversial topic: when to pull epidural catheters in patients receiving warfarin or Low Molecular Weight Heparin (LMWH) prophylaxis.
1.Does it really matter when you remove the epidural catheter in an anticoagulated patient?
2.Are there any guidelines for the removal of epidural catheters in anticoagulated patients?
今天我们通过一非常有争议的话题结束讨论：对于接受华发林或LMWH预防性治疗的患者什么时候拔除硬膜外导管。
1.对抗凝患者拔除硬膜外导管时真的重要吗?为什么？
2.抗凝患者拔除硬膜外导管遵循原则是什么？

参考答案
1.对抗凝患者拔除硬膜外导管时真的重要吗?为什么？
拔除硬膜外导管如同放置导管一样具有创伤性。Vandermeulen及其同事回顾性分析了61例在硬膜外或蛛网膜下腔麻醉后发生椎管内血肿病历后发现，其中53例（或87%）因抗凝药物使用而导致凝血功能异常，或穿刺针置入及导管拔除时凝血功能障碍。此外硬膜外麻醉下发生率为75%（46/61），而其中47%发生在拔除导管时。作者通过这些结果得出结论：在凝血功能异常患者及导致椎管内血肿的风险上，拔除硬膜外导管与放置同样重要[1]。
2.抗凝患者拔除硬膜外导管遵循原则是什么？
ASRA关于轴索麻醉和抗凝状态一致强调，对于接受口服抗凝药治疗患者拔除硬膜外导管没有作出确定的建议。他们进一步强调当决定是否拔除硬膜外导管时，应该进行临床判断。指南建议在导管拔除后进行神经病学测验24小时，如果在导管拔除时INR>1.5，评估应该超过24小时[2]。
治疗剂量的非分化肝素（使PTT达到60-80）经常用于接收轴索麻醉患者。ASRA指南建议导管拔除前，肝素应停止使用2-4小时并评估PTT。拔除导管后1小时内不用肝素[3]。
正如我们上周所述，LMWH生物利用度好、半衰期长、剂量反应可以预测，是现在常用的的抗凝选择。在最后一次剂量LMWH后导管拔除至少推迟10-12小时，导管拔除后至少2小时后方可使用LMWH[4]。我们在Brigham and Women's Hospital的做法是：在最后一次LMWH后24小时拔除导管，此时凝血功能完全正常。
对于凝血链的完整理解及如何确定药物的影响对于我们实施局部麻醉与镇痛很重要。过去两周我们回顾了在外科手术前和局部操作技术前抗凝治疗的管理主题。我们也回顾了在通常使用抗凝治疗情况下连续轴索镇痛方法的使用。

Does it really matter when you remove the epidural catheter in an anticoagulated patient?
Removal of an epidural catheter could be as traumatic as the placement. Vandermeulen and colleagues reviewed 61 case reports of spinal hematoma after epidural or subarachnoid anesthesia and found that 53/61 cases or 87% had an abnormality in coagulation because of an anticoagulant drug or a clotting disorder at the time of needle placement or catheter removal. Furthermore 75% of cases (46/61) happened when an epidural anesthetic was used and of those 47% (15/32) occurred when the epidural catheter was removed. These results lead the authors to the conclusion that removal of an epidural catheter is just as critical as the placement in terms of coagulation abnormalities and the risk of a spinal hematoma (1).

Are there any guidelines for the removal of epidural catheters in anticoagulated patients?
The American Society of Regional Anesthesia (ASRA) consensus statements on neuraxial anesthesia and anticoagulation states that no definitive recommendation can be made for removal of epidural catheters in patients with therapeutic levels of oral anticoagulants. They further state that clinical judgment should be used when making decisions about removing epidural catheters. The guidelines recommend neurologic testing for 24 hours after catheter removal and longer than 24 hours if the INR >1.5 at the time of catheter removal (2).
Unfractionated heparin in therapeutic doses (to try to achieve a partial thromboplastin time (PTT) of 60-80) is occasionally used in patients receiving neuraxial analgesia. The ASRA guidelines recommend that prior to catheter removal the heparin be discontinued for 2-4 hours and that the PTT be evaluated. The heparin should be withheld for one additional hour after catheter removal (3).
As mentioned last week, low molecular weight heparin (LMWH) has a good bioavailability, long half-life, and predictable dose response and is now the anticoagulant of choice in many situations. Catheter removal should be delayed at least 10-12 hours after the last dose of LMWH and the next dose should not be given until two hours after catheter removal (4). Our practice at the Brigham and Women's Hospital is to remove epidural catheters 24 hours after the last dose of LMWH as a complete normalization of the coagulation is achieved at this time.
A complete understanding of the coagulation cascade and how certain medications affect it is essential for our practice of regional anesthesia and analgesia. During the last two weeks we have reviewed this topic as well as the management of anticoagulants prior to a surgical procedure and prior to a regional technique. We have also reviewed the use of continuous neuraxial analgesia in the presence of commonly used anticoagulants.
Question Author: David Hepner, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School
References:
1.  Vandermeulen EP, Van Aken H, Vermylen J. Anticoagulants and spinal-epidural anesthesia. Anesth Analg 1994;79:1165-77.
2.  Enneking KF, Benzon HT. Oral anticoagulants and regional anesthesia: A perspective. Reg Anesth Pain Med 1998:23 Suppl. 3.
3.  Liu SS, Mulroy MF. Neuraxial anesthesia and analgesia in the presence of standard heparin. Reg Anesth Pain Med 1998:23 Suppl. 6.
4.  Horlocker TT, Wedel DJ. Neuraxial block and low molecular weight heparin: balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998:23 Suppl. 7-8.
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Department of Anesthesia, Harvard Medical School
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Department of Anesthesiology, Perioperative and Pain Medicine, Harvard Medical School