Residual Enoxaparin Activity, Anti-Xa Levels, and Concerns About the American Society of Regional Anesthesia and Pain Medicine Anticoagulation Guidelines. Issue 4 (July 2017)

• Record Type: Journal Article
• Authors: Henshaw, Daryl S.; Turner, James D.; Forest, Daniel J.; Thompson, Garrett R.; Weller, Robert S.
• Is Part Of: Regional anesthesia and pain medicine. Volume 42:Issue 4(2017)
• Publication Date: 2017-07
• Subjects: Conduction anesthesia -- Periodicals; Pain medicine -- Periodicals; 617.964
• DOI: 10.1097/AAP.0000000000000617
• Languages: English
• ISSNs: 1098-7339

Abstract

Abstract : Abstract: Currently, the American Society of Regional Anesthesia and Pain Medicine (ASRA) anticoagulation guidelines recommend that before the performance of a neuraxial procedure a minimum of 24 hours should elapse following a treatment dose of enoxaparin (1 mg/kg twice daily or 1.5 mg/kg once daily). The guidelines have since their inception also consistently recommended against the routine use of anti-Xa level monitoring for patients receiving enoxaparin. However, we noted in our clinical practice that anti-Xa levels were frequently still elevated despite patients meeting the time-based recommendation for treatment dose enoxaparin. To further investigate the possibility that residual anticoagulant activity may persist longer than 24 hours after a treatment dose of enoxaparin, we assessed anti-Xa level activity in patients presenting for elective surgery. Despite nearly universal compliance with ASRA's anticoagulation guidelines (1 sample was drawn at 23.25 hours), anti-Xa activity was found to be elevated in 11 of 19 patients. While 10 patients had an anti-Xa level within the peak prophylactic range (0.2–0.5 IU/mL), 1 patient's level was found to still be in the peak therapeutic range (0.5–1.0 IU/mL). These findings suggest that significant anticoagulant activity may persist longer than previously appreciated after the last treatment dose of enoxaparin and that the current time-based ASRA recommendation may not be conservative enough. Further research is needed to delineate the level of anti-Xa activity below which it is likely safe to proceed with a neuraxial procedure, but it may be time to reconsider the utility of anti-Xa level monitoring when it is available.