Neuraxial anesthesia and anticoagulation

Published on 07/02/2015 by admin

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Last modified 07/02/2015

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Neuraxial anesthesia and anticoagulation

Terese T. Horlocker, MD

The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with neuraxial blockade is unknown; however, the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural anesthetics and less than 1 in 220,000 spinal anesthetics. In 57 of 61 (87%) cases of spinal hematoma associated with epidural or spinal anesthesia, a hemostatic abnormality or traumatic or difficult needle placement was present. More than one of these risk factors was present in 20 of 61 cases. Neurologic dysfunction tended to be reversible in patients who underwent laminectomy within 8 h of onset of neurologic dysfunction.

The American Society of Anesthesiologists Closed Claims project noted that spinal cord injuries were the leading cause of claims in the 1990s. Spinal hematomas accounted for nearly half of the claims related to spinal cord injuries. The primary risk factor for spinal hematoma was epidural anesthesia in the presence of intravenously administered heparin during a vascular surgical or diagnostic procedure. Importantly, the presence of postoperative numbness or weakness was typically initially attributed to the effect of the local anesthetic agent rather than to spinal cord ischemia, which delayed the diagnosis. Patient care was rarely judged to have met standards (12 of 13 cases did not meet standards), and the median payment for the claim was very high.

In a review of nearly 2 million neuraxial blocks, there were 33 spinal hematomas, with the risk associated with epidural analgesia in women undergoing childbirth significantly less (1 in 200,000) than that in elderly women undergoing knee arthroplasty (1 in 3600, p <0.0001). Likewise, women undergoing operations under spinal anesthesia to repair a hip fracture had an increased risk of developing a spinal hematoma (1 in 22,000) compared with all patients undergoing spinal anesthesia (1 in 480,000).

Overall, these series suggest that the risk of clinically significant bleeding varies with age (and associated abnormalities of the spinal cord or vertebral column), the presence of an underlying coagulopathy, difficulty during needle placement, and an indwelling neuraxial catheter during sustained anticoagulation (particularly with standard heparin or low-molecular-weight heparin [LMWH]). Prompt diagnosis and intervention are critical to prevent or attenuate permanent neurologic dysfunction.

Intravenously and subcutaneously administered standard heparin

Several large studies have documented the safety of short-term intravenously administered heparinization in patients undergoing neuraxial anesthesia, provided that the heparin activity is closely monitored, indwelling catheters are removed at a time when circulating heparin levels are relatively low, and patients with a preexisting coagulation disorder are not included in the study. Conversely, traumatic needle placement, initiation of anticoagulation within 1 h of needle insertion, or concomitant aspirin therapy have been identified as risk factors in the development of spinal hematoma in patients receiving anticoagulant therapy.

Intravenous heparin administration should be delayed for 1 h after needle placement. Indwelling catheters should be removed 1 h before a subsequent heparin administration or 2 to 4 h after the last heparin dose. Evaluation of the patient’s coagulation status may be appropriate before catheter removal if the patient has demonstrated enhanced response to heparin or is receiving high doses of heparin. Although a bloody or difficult needle placement may increase risk, no data support mandatory cancellation of a case should this occur. Prolonged therapeutic anticoagulation appears to increase the risk of spinal hematoma formation, especially if combined with other anticoagulants or thrombolytic agents. Therefore, neuraxial blocks should be avoided in this clinical setting. If systematic anticoagulation therapy is begun with an epidural catheter in place, catheter removal should be delayed for 2 to 4 h after discontinuation of heparin and after evaluation of coagulation status (Table 125-1).

Table 125-1

Recommendations for Management of Patients Receiving Neuraxial Blockade and Anticoagulant Drugs

Drug	Recommendations
Warfarin	Discontinue chronic warfarin therapy 4-5 days before spinal procedure and evaluate INR. INR should be within the normal range at time of procedure to ensure adequate levels of all vitamin K-dependent factors. Postoperatively, INR should be assessed daily with catheter removal occurring with an INR <1.5.
Antiplatelet medications	No contraindications with aspirin or other NSAIDs. Thienopyridine derivatives (clopidogrel and ticlopidine) should be discontinued 7 days and 14 days, respectively, before procedure. GP IIb/IIIa inhibitors should be discontinued to allow recovery of platelet function before procedure (8 h for tirofiban and eptifibatide, 24-48 h for abciximab).
Thrombolytics/fibrinolytics	There are no available data to suggest a safe interval between procedure and initiation or discontinuation of these medications. Follow fibrinogen level and observe the patient for signs of neural compression.
LMWH	Delay procedure at least 12 h from the last dose of thromboprophylaxis LMWH dose. For “treatment” dosing of LMWH, at least 24 h should elapse before initiation of procedure. LMWH should not be administered within 24 h after the procedure. Indwelling epidural catheters should be maintained with caution and only with once-daily dosing of LMWH and strict avoidance of additional hemostasis-altering medications, including ketorolac.
Unfractionated SQ heparin	There are no contraindications to neuraxial procedure if total daily dose is less than 10,000 units. For higher dosing regimens, manage according to intravenous heparin guidelines.
Unfractionated IV heparin	Delay needle/catheter placement 2-4 h after last dose; document normal aPTT. Heparin may be restarted 1 h after procedure. Sustained heparinization with an indwelling neuraxial catheter is associated with increased risk; monitor the patient’s neurologic status aggressively.

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