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1.Can surgery be performed with elevated INR levels?
2.Are there any studies evaluating the patients receiving chronic warfarin therapy and regional anesthesia?
3.What about evidence regarding perioperative warfarin therapy and regional anesthesia?

1.国际标准比值抬高是否可行手术？
2.是否有文献评估接受长期华法林治疗和局部麻醉关系？
3.有关围术期华法林治疗和局部麻醉关系的证据有哪些？

参考答案（请战友指正)

1 国际标准比值抬高是否可行手术？Brickey等在一动物模型中致力于确定一用于预测在进行经气管钳活检(TBBx)后出血时的凝血紊乱水平，如国际标准化比值水平。在18头Yucatan幼猪中应用交叉双盲研究，作者在TBBx后进行纤维支气管镜检查观察了凝血系统正常时动物出血量，随后给予大剂量华法林以升高国际标准化比值，国际标准化比值的最终目标是使等于或大于50%的动物出血量大于或等于100 mL。尽管有些动物的INR水平大于10，但TBBx后没有出血并发症，11个动物INRs > 7.。作者得出结论认为在此动物模型中TBBx后出血风险与INR抬高不成相关关系。
2 是否有文献评估接受长期华法林治疗和局部麻醉关系？
迄今为止，对于慢性和不间断口服抗凝药患者进行局部麻醉的研究论文未见报道。然而有一病案报道，一服用苯丙香豆素（一长效维生素K拮抗剂）抗凝的患者，硬膜外置管困难。当时的麻醉医生没有注意到其使用了抗凝剂。麻醉起效和麻醉效果很满意，但术后第三天，患者下肢截瘫合并大小便失禁。尽管进行了硬膜外血肿清除，截瘫一直未康复。此病案符合4级和3级证据(专家意见和大量肝素抗凝的研究)，除了极特殊情况，在大剂量华法林治疗时应避免进行椎管麻醉。
3 有关围术期华法林治疗和局部麻醉关系的证据有哪些？
虽然有一些大型实验研究了运用局部麻醉与镇痛对围术期接受华法林治疗以预防血栓栓塞，但能够监测到这些并发症的效能很低，结论为应该对于服用华法林患者应该谨慎使用局麻方法。
Odoom and Sih报道了1000例硬膜外麻醉用于血管手术的经验，这些患者术前均服用华法林并记录了硬膜外置管期间抗凝资料（通过凝血试验），术中，患者使用了肝素，血液丢失使用新鲜冰冻血浆替代。术后进行硬膜外镇痛并定期进行神经系统检查。48小时时，拔出导管。结果未发生神经系统并发症。

英文参考答案：
1 Can surgery be performed with elevated INR levels?
Brickey et al. (1) sought to identify a level of coagulopathy, reported as the international normalized ratio (INR), which could predict hemorrhage following transbronchial forceps biopsy (TBBx) in an animal model. Utilizing a crossover blinded study in 18 Yucatan mini-swine, the authors performed flexible fiberoptic bronchoscopy with TBBx to establish the amount of bleeding in animals with normal coagulation systems. Animals then were administered escalating dosages of warfarin to obtain one of several increased INR levels. The endpoint was defined as the INR that resulted in a blood loss of > or = 100 mL in > or = 50% of the study animals. Despite INR levels > 10 in some animals, no hemorrhagic complications of the transbronchial forceps biopsy (TBBx) were noted. Eleven animals had INRs > 7. The authors concluded that INR elevation did not correlate with an increased risk of bleeding following TBBx in this animal model.
2 Are there any studies evaluating the patients receiving chronic warfarin therapy and regional anesthesia?
To date, there have been no investigations in patients receiving chronic, uninterrupted oral anticoagulation and regional anesthesia. However, one case report (2) noted the placement of a technically difficult epidural catheter in a patient who was fully anticoagulated with phenprocoumon, a long-acting oral vitamin K antagonist. The anesthesiologist was unaware of the anticoagulation. Following the onset and resolution of satisfactory surgical anesthesia, on the third postoperative day, the patient developed paresis of the lower extremities with bowel and bladder impairment. Despite evacuation of an epidural hematoma, the paresis was not reversed. This case agrees with the level 4 and level 3 evidence (expert consensus and studies with full heparin anticoagulation) which note that except in exceptional circumstances, central neuraxial blockade should be avoided in presence of full therapeutic warfarin anticoagulation (3).
3 What about evidence regarding perioperative warfarin therapy and regional anesthesia?
Although several large studies have examined the use of regional anesthesia and analgesia in patients who received warfarin in the perioperative period for thromboembolism prophylaxis, their power to detect these rare complications is low, and the results, though somewhat comforting, recommend caution.
Odoom and Sih (4), reported their experience in providing 1,000 epidural blocks for vascular procedures, where all patients received preoperative warfarin and were documented to be anticoagulated (by the thrombotest) at time of epidural catheter insertion. Intraoperatively, the patients received heparin and blood loss was replaced by fresh frozen plasma. Postoperatively, epidural analgesia was provided and neurologic exams were performed routinely. At 48 hrs, the catheters were removed. No neurological complications occurred.

References:
1.Brickey DA, Lawlor DP. Transbronchial biopsy in the presence of profound elevation of the international normalized ratio. Chest 1999 Jun;115:1667-71.
2.Wille-Jorgensen P, Jorgensen LN, Rasmussen LS. Lumbar regional anesthesia and prophylactic anticoagulant therapy: Is the combination safe? Anaesthesia 1991;46:623-7.
3.Paech M, Anticoagulants and regional anesthesia. IARS 2000 Review Course Lectures. Anesth Analg 2000;90:Suppl 35-41.
4.Odoom JA, Sih IL. Epidural analgesia and anticoagulant therapy: experience with one thousand cases of continuous epidurals. Anaesthesia 1983;38:254-9.