Regional Anesthesia and Pain Medicine • Volume 40, Number 4, July-August 2015 3. Klein SM, D’Ercole F, Greengrass RA, Warner DS. Enoxaparin associated with psoas hematoma and lumbar plexopathy after lumbar plexus block. Anesthesiology. 1997;87:1576–1579. 4. Benzon HT, Avram MJ, Green D, Bonow RO. New oral anticoagulants and regional anaesthesia. Br J Anaesth. 2013;111(suppl 1): i96–i113. 5. Benzon HT, Avram MJ, Benzon HA, Kirby-Nolan M, Nader A. Factor VII levels and international normalized ratios in the early phase of warfarin therapy. Anesthesiology. 2010;112:298–304. 6. Horlocker TT, Wedel DJ, Rowlingson JC, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (third edition). Reg Anesth Pain Med. 2010;35:64–101. 7. Gogarten W, Vandermeulen E, van Aken H, et al. Regional anaesthesia and antithrombotic agents: recommendations of the European Society of Anaesthesiology. Eur J Anaesthesiol. 2010;27: 999–1015.
Reply to Dr Chelly Accepted for publication: April 22, 2015. To the Editor: e thank Dr Chelly for his letter1 to the editor regarding our recently published article.2 Dr Chelly notes that we reported our discovered rates of local oozing and development of a palpable mass, stating that this is likely due to local tissue trauma as opposed to the combination of the continuous femoral nerve block and the use of rivaroxaban. We have similarly noted local tissue trauma as a risk factor with regard to oozing and possible hematoma formation for our patients as discussed in our article. Our results show that, despite local tissue trauma that might occur during the placement of a nerve block catheter, it is safe to maintain the catheter in situ for up to 48 hours and begin thromboprophylaxis with rivaroxaban for this patient population. Furthermore, our data demonstrate the safety of our approach in an academic teaching center, where both experienced regional anesthesiologists and
W
those with less experience (ie, physicians acquiring new regional anesthesia skills, be it staff physicians, fellows, or residents) are involved in direct patient care and block placement. The risk of local tissue trauma decreases as one gains clinical experience, but it remains a risk even in experienced hands. As new techniques and approaches are used for providing regional anesthesia, such as the approach described in your letter, we appreciate that there exists an opportunity to further enhance patient safety. With regard to the administration of 1 dose of rivaroxaban prior to the removal of our femoral catheters as per our protocol, we agree that based on the pharmacokinetics a “steady state” and full anticoagulation is unlikely to have occurred for our patients. However, our study was the first to assess the use and safety of rivaroxaban in combination with an indwelling nerve block catheter. Although full anticoagulation might not have been achieved, we believe the study is an important first step in demonstrating concomitant use of this recently introduced anticoagulation medication and an indwelling catheter. As we have gained experience in this clinical setting, we note that for patients with a nerve block catheter that remains beyond postoperative day 2 (ie, for patients with chronic pain in whom we offer continuous block catheters for up to 5 days), we continue to administer rivaroxaban daily. In such circumstances, we have not experienced any adverse effects beyond what we have reported in our article. As you have indicated, our protocol was developed to mimic previously published guidelines—in keeping with patient safety. Although the pharmacokinetics of rivaroxaban would suggest that the catheter could be removed safely prior to a 20-hour drug-free interval, removal of the catheter prior to that time was not clinically necessary. At our institution, following the administration of rivaroxaban on the first postoperative day, patients continue to receive the analgesic benefit from the femoral nerve block catheter during their physiotherapy and subsequently throughout the night until the catheter is removed on the morning of postoperative day 2. Furthermore, as our study was the first to use this medication simultaneously with an indwelling catheter, we felt it prudent to
© 2015 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
create the safest, most feasible protocol we could for our patients. Historically, the clinical application of pharmacokinetic knowledge has not always proved safe. Specifically, following the introduction of twice-daily administration of low-molecularweight heparin for thromboprophylaxis, the incidence of spinal hematoma increased sharply.3 Despite the best intentions of the practitioner, catastrophic events occurred when anticoagulation medications and invasive medical procedures mixed.3 Indeed, the American Society of Regional Anesthesia and the European Society of Anaesthesiology recommend against the routine use of twice-daily dosing of thromboprophylactic low-molecular-weight heparin with an indwelling epidural catheter.3,4 Perhaps an interval of 2 half-lives or more is not really required; however, why would we not wait? Chris Idestrup, MD, MSc, FRCPC Department of Anesthesia Sunnybrook Health Sciences Centre University of Toronto Toronto, Ontario, Canada
The author declares no conflict of interest. REFERENCES 1. Chelly JE. Risk of bleeding associated with the combination of thromboprophylaxis and peripheral nerve blocks: role of the technique. Reg Anesth Pain Med. 2015;40:396–397. 2. Idestrup C, Sawhney M, Nix C, Kiss A. The incidence of hematoma formation in patients with continuous femoral catheters following total knee arthroplasty while receiving rivaroxaban as thromboprophylaxis: an observational study. Reg Anesth Pain Med. 2014;39:414–417. 3. Horlocker TT, Wedel DJ, Rowlingson JC, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (third edition). Reg Anesth Pain Med. 2010;35:64–101. 4. Gogarten W, Vandermeulen E, van Aken H, Kozek S, Llau JV, Samama CM. European Society of Anaesthesiology. Regional anaesthesia and antithrombotic agents: recommendations of the European Society of Anaesthesiology. Eur J Anaesthesiol. 2010;27:999–1015.
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Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Reply to Dr Chelly Accepted for publication: April 22, 2015. To the Editor: e thank Dr Chelly for his letter1 to the editor regarding our recently published article.2 Dr Chelly notes that we reported our discovered rates of local oozing and development of a palpable mass, stating that this is likely due to local tissue trauma as opposed to the combination of the continuous femoral nerve block and the use of rivaroxaban. We have similarly noted local tissue trauma as a risk factor with regard to oozing and possible hematoma formation for our patients as discussed in our article. Our results show that, despite local tissue trauma that might occur during the placement of a nerve block catheter, it is safe to maintain the catheter in situ for up to 48 hours and begin thromboprophylaxis with rivaroxaban for this patient population. Furthermore, our data demonstrate the safety of our approach in an academic teaching center, where both experienced regional anesthesiologists and
W
those with less experience (ie, physicians acquiring new regional anesthesia skills, be it staff physicians, fellows, or residents) are involved in direct patient care and block placement. The risk of local tissue trauma decreases as one gains clinical experience, but it remains a risk even in experienced hands. As new techniques and approaches are used for providing regional anesthesia, such as the approach described in your letter, we appreciate that there exists an opportunity to further enhance patient safety. With regard to the administration of 1 dose of rivaroxaban prior to the removal of our femoral catheters as per our protocol, we agree that based on the pharmacokinetics a “steady state” and full anticoagulation is unlikely to have occurred for our patients. However, our study was the first to assess the use and safety of rivaroxaban in combination with an indwelling nerve block catheter. Although full anticoagulation might not have been achieved, we believe the study is an important first step in demonstrating concomitant use of this recently introduced anticoagulation medication and an indwelling catheter. As we have gained experience in this clinical setting, we note that for patients with a nerve block catheter that remains beyond postoperative day 2 (ie, for patients with chronic pain in whom we offer continuous block catheters for up to 5 days), we continue to administer rivaroxaban daily. In such circumstances, we have not experienced any adverse effects beyond what we have reported in our article. As you have indicated, our protocol was developed to mimic previously published guidelines—in keeping with patient safety. Although the pharmacokinetics of rivaroxaban would suggest that the catheter could be removed safely prior to a 20-hour drug-free interval, removal of the catheter prior to that time was not clinically necessary. At our institution, following the administration of rivaroxaban on the first postoperative day, patients continue to receive the analgesic benefit from the femoral nerve block catheter during their physiotherapy and subsequently throughout the night until the catheter is removed on the morning of postoperative day 2. Furthermore, as our study was the first to use this medication simultaneously with an indwelling catheter, we felt it prudent to
© 2015 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
create the safest, most feasible protocol we could for our patients. Historically, the clinical application of pharmacokinetic knowledge has not always proved safe. Specifically, following the introduction of twice-daily administration of low-molecularweight heparin for thromboprophylaxis, the incidence of spinal hematoma increased sharply.3 Despite the best intentions of the practitioner, catastrophic events occurred when anticoagulation medications and invasive medical procedures mixed.3 Indeed, the American Society of Regional Anesthesia and the European Society of Anaesthesiology recommend against the routine use of twice-daily dosing of thromboprophylactic low-molecular-weight heparin with an indwelling epidural catheter.3,4 Perhaps an interval of 2 half-lives or more is not really required; however, why would we not wait? Chris Idestrup, MD, MSc, FRCPC Department of Anesthesia Sunnybrook Health Sciences Centre University of Toronto Toronto, Ontario, Canada
The author declares no conflict of interest. REFERENCES 1. Chelly JE. Risk of bleeding associated with the combination of thromboprophylaxis and peripheral nerve blocks: role of the technique. Reg Anesth Pain Med. 2015;40:396–397. 2. Idestrup C, Sawhney M, Nix C, Kiss A. The incidence of hematoma formation in patients with continuous femoral catheters following total knee arthroplasty while receiving rivaroxaban as thromboprophylaxis: an observational study. Reg Anesth Pain Med. 2014;39:414–417. 3. Horlocker TT, Wedel DJ, Rowlingson JC, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (third edition). Reg Anesth Pain Med. 2010;35:64–101. 4. Gogarten W, Vandermeulen E, van Aken H, Kozek S, Llau JV, Samama CM. European Society of Anaesthesiology. Regional anaesthesia and antithrombotic agents: recommendations of the European Society of Anaesthesiology. Eur J Anaesthesiol. 2010;27:999–1015.
397
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
