1.5 Antithrombotic drugs and neuraxial anesthesia/analgesia
The benefits of neuraxial blockade (ie, spinal or epidural anesthesia and continuous epidural analgesia) are well-established.[162] [163] [164] [165] [166] [167] The risk of perispinal hematoma, a very rare but potentially devastating complication after neuraxial blockade, may be increased with the concomitant use of antithrombotic drugs.[168] [169] Bleeding into the enclosed space of the spinal canal can produce spinal cord ischemia and subsequent paraplegia. The seriousness of this complication mandates the cautious use of all antithrombotic medications in patients undergoing neuraxial blockade. A 1997 Food and Drug Administration public health advisory[170] [171] reported 41 US patients who developed perispinal hematoma after receiving the LMWH enoxaparin around the time of spinal/epidural anesthesia. Some patients had preexisting spinal abnormalities, and a third had received additional hemostasis-inhibiting medications. Nearly 90% of the cases occurred among patients receiving enoxaparin as thromboprophylaxis after knee or hip replacement or after spinal surgery. Many of these patients experienced neurologic impairment, including permanent paralysis, despite undergoing a decompressive laminectomy. Additional cases of perispinal hematoma in patients who have received LMWH have been reported. This complication also has been reported with the use of LDUH, although apparently with lower frequency.
Most patients who develop perispinal hematomas have more than one risk factor for local or systemic bleeding, including the presence of an underlying hemostatic disorder, anatomic or vascular vertebral column abnormalities, traumatic needle or catheter insertion, repeated insertion attempts, insertion in the presence of high levels of an anticoagulant, the use of continuous epidural catheters, the concurrent administration of medications known to increase bleeding, high anticoagulant dosage, older age, and female gender.[168] [170] [171] Removal of the epidural catheter, especially in the presence of an anticoagulant effect, has also been associated with hematoma.[168] Unfortunately, the prevalence of perispinal hematoma and the predictive value of the various risk factors remain unknown. As a result, reviews on the use of antithrombotic therapy among recipients of neuraxial anesthesia[169] [172] [173] combine the limited available evidence with practical advice. A detailed discussion of this topic is available through the American Society of Regional Anesthesia and Pain Medicine (www.asra.com).[169]
Consideration of neuraxial anesthesia plus or minus postoperative epidural analgesia requires a review of the intended benefits and the potential risks. A careful history will identify most patients with an important underlying bleeding disorder and those receiving agents that affect hemostasis or platelet function. In keeping with the American Society of Regional Anesthesia recommendations, we believe that neuraxial blockade and anticoagulant thromboprophylaxis, including the use of LDUH and LMWH, can generally be used concurrently as long as there is appropriate caution.
The following suggestions may improve the safety of neuraxial blockade in patients who have or will receive anticoagulant prophylaxis. (1) Neuraxial anesthesia/analgesia should generally be avoided in patients with a known bleeding disorder. (2) Neuraxial anesthesia should generally be avoided in patients whose preoperative hemostasis is impaired by antithrombotic drugs. Nonsteroidal anti-inflammatory agents and aspirin do not appear to increase the risk of perispinal hematoma. Since less is known about the safety of the thienopyridine platelet inhibitors clopidogrel and ticlopidine in patients undergoing neuraxial block, the discontinuation of these drugs 5 to 14 days before the procedure should be considered. In patients receiving preoperative anticoagulants, the insertion of the spinal needle or epidural catheter should be delayed until the anticoagulant effect of the medication is minimal. This is usually at least 8 to 12 h after a subcutaneous dose of heparin or a twice daily prophylactic dose of LMWH, or at least 18 h after a once-daily LMWH injection. (3) Anticoagulant prophylaxis should be delayed if a hemorrhagic aspirate (ie, a “bloody tap”) is encountered during the initial spinal needle placement. (4) Removal of an epidural catheter should be done when the anticoagulant effect is at a minimum (usually just before the next scheduled subcutaneous injection). (5) Anticoagulant prophylaxis should be delayed for at least 2 h after spinal needle or epidural catheter removal. (6) If prophylaxis with a VKA, such as warfarin, is used, we recommend that continuous epidural analgesia not be used for longer than 1 or 2 days because of the unpredictable anticoagulant effect of the anticoagulant. Furthermore, if prophylaxis with a VKA is used at the same time as epidural analgesia, the international normalized ratio (INR) should be < 1.5 at the time of catheter removal. (7) Although postoperative prophylaxis with fondaparinux appears to be safe in patients who have received a spinal anesthetic, there are no safety data about its use along with postoperative continuous epidural analgesia. The long half-life of fondaparinux and its renal mode of excretion raise concerns about the potential for accumulation of the drug, especially in the elderly because of the associated impairment of renal function. Until further data are available, we recommend that fondaparinux not be administered along with continuous epidural analgesia.
With the concurrent use of epidural analgesia and anticoagulant prophylaxis, all patients should be monitored carefully and frequently for the symptoms and signs of cord compression. These symptoms include progression of lower extremity numbness or weakness, bowel or bladder dysfunction, and new onset of back pain. If spinal hematoma is suspected, diagnostic imaging and definitive surgical therapy must be performed rapidly to reduce the risk of permanent paresis. We encourage every hospital that uses neuraxial anesthesia/analgesia to develop written protocols that cover the most common scenarios in which these techniques will be used along with antithrombotic agents.
Recommendation: Neuraxial Anesthesia/analgesia
1.5.1. In all patients undergoing neuraxial anesthesia or analgesia, we recommend special caution when using anticoagulant prophylaxis (Grade 1C+).