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Anticoagulated patients and neuraxial anaesthesia

Anticoagulated patients and neuraxial anaesthesia. Dr.Srinivas Kallam Consultant anaesthetist, University Hospitals Leicester NHS trust. introduction. The widespread use of CNB and the prevalence of anticoagulation have led to an inevitable overlap between the two

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Anticoagulated patients and neuraxial anaesthesia

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  1. Anticoagulated patients and neuraxial anaesthesia Dr.Srinivas Kallam Consultant anaesthetist, University Hospitals Leicester NHS trust

  2. introduction • The widespread use of CNB and the prevalence of anticoagulation have led to an inevitable overlap between the two • The most serious complication of CNB in anticoagulated patients is the risk of spinal/epidural haematoma(SEH)

  3. introduction • CNB in these patients is a complex decision if anticoagulation therapies were to be stopped • Various guidelines have been issued to achieve normal haemostasis • the evidence base for many such recommendations is weak • it is crucial to fully assess individual risk factors and understand anticoagulant pharmacokinetics

  4. NAP3 • The NAP3 in 2009 =707 425 CNB/annum • 41% were epidurals, 46% were spinals • 84 major complications were reported

  5. The most important part of the management process - individualized preoperative assessment for the risks of thromboembolism in the absence of anticoagulation and SEH

  6. Once the decision to perform CNB has been made • (i) a schedule for cessation of anticoagulation • (ii) a safe interval for initiating thromboprophylaxis postoperatively • (iii) postoperative surveillance for signs of spinal cord compression

  7. Numerous recommendations and guidelines have been issued across Europe and the USA • newer licensed agents, such as dabigatran etexilate (Pradaxa) and rivaroxaban (Xarelto)

  8. Thromboembolic risk assessment • The highest risk for recurrent VTE is within the first 3 months following an acute episode of VTE • patients who discontinue clopidogrel prematurely within the first month of having a coronary stent insertion are more likely to die within the year compared with those who continue treatment (7·5% vs. 0·7%, P < 0·0001) (Spertus et al, 2006)

  9. Thromboembolic risk assessment • Patients with atrial fibrillation and high CHADS-2 score have a high risk of stroke without antithrombotic therapy • postpone elective surgery

  10. Thromboembolic risk assessment • CNB, when compared with general anaesthesia (GA), reduces the odds of VTE by 44% for DVT and 55% for PE after orthopaedic surgery (Rodgers et al, 2000) • using fondaparinux have failed to corroborate this advantage (Turpie et al, 2003)

  11. Haemostatic requirements during CNB • pts with no bleeding history, routine coagulation screening is not required (Chee et al, 2008) • “minimum platelet threshold” for performing CNB • at least 50 × 109/l (BCSH, 2003a) • for immune thrombocytopenia minimum of 80 × 109/l (BCSH, 2003b).

  12. Risk factors of SEH • presence of multiple risk factors substantially increases the risk of SEH, despite safety guidelines having been followed

  13. Unfractionated heparin • Pts receiving UFH should have an APTT checked prior to catheter insertion/removal • If UFH has been administered for >4 d, check platelet count prior to CNB to exclude HIT (Tryba, 1998) • The question as to whether to proceed with or abort surgery after a bloody tap remains unanswered • a delay of 6 and 12 h is presently recommended in Spain and Germany respectively (Gogarten et al, 2003;Llau et al, 2007)

  14. LMWH • Monitoring anti Xa activity • pregnant, obese or have severe renal impairment (Baglin et al, 2006a). • In the UK, LMWHs have almost completely replaced UFH • Platelet count should be checked prior to catheter insertion/removal on patients who have received LMWH for >4 d, in order to rule out the small risk of HIT (Keeling et al, 2006).

  15. fondaparinux • Fondaparinux is a synthetic indirect inhibitor of factor Xa which has a half-life of 17–21 h • A meta-analysis of phase III clinical trials in orthopaedic surgeries showed that fondaparinux, when compared to LMWH, was more effective in VTE prevention and when given >6 h after surgery the risks of bleeding were similar (Turpie et al, 2002)

  16. fondaparinux • In the UK fondaparinux is licensed for thromboprophylaxis after major orthopaedic surgery (NICE, 2007) • Not recommended with indwelling neuraxial catheters

  17. Coumarin derivative • Warfarin inhibits the synthesis and vitamin K-dependent clotting factors II, VII, IX, X, as well as Proteins C, S and Z • The prothrombin time (PT) or international normalized ratio (INR) is the most commonly used test to monitor warfarin

  18. warfarin • The complete and immediate reversal of warfarin can be achieved with clotting factor concentrates (Makris et al, 1997) and vitamin K (Watson et al, 2001)

  19. warfarin • should stop warfarin 4–5 d prior to CNB and “bridging therapy” with LMWH or UFH should be initiated (Kearon & Hirsh, 1997; Heit, 2001). • The INR should be checked prior to CNB in all patients. • An INR of <1·4 prior to catheter manipulation is recommended

  20. New oral anticoagulants • The limitations of the current anticoagulants • refined target and the need for monitoring is not required due to their predictable dose-response relationship • Recently dabigatran etexilate and rivaroxaban have successfully undergone NICE technology appraisals (NICE, 2008, 2009) for thromboprophylaxis following major orthopaedic surgery

  21. New oral anticoagulants • Dabigatran • direct thrombin inhibitor • half-life 12–17 h and the peak plasma concentration 0·5–2 h • The dose of for thromboprophylaxis is 220 mg once daily, being administered initially as a half dose of 110 mg, 1–4 h after surgery

  22. New oral anticoagulants • Rivaroxaban • oral direct Xa inhibitor • oral bioavailability of 80–100% and peak plasma level is reached after 3–4 h. t1/2 is 5–9 h. Rivaroxaban prolongs both PT and APTT dose-dependently (Kubitza et al, 2005) • prophylactic dose 10 mg once daily, with the first dose administered 6–8 h after surgery.

  23. New oral anticoagulants • Apixaban • Another direct oral factor Xa inhibitor prophylaxis and treatment of VTE (Lassen et al, 2007; Buller et al, 2008).

  24. Anti-platelet agents • NSAID • Aspirin, (COX-1) inhibitor that irreversibly inhibits platelet function • Other COX-1 inhibitors, such as naproxen, ibuprofen and diclofenac - reversible inhibitors and platelet function returns to normal in 2-3 days after stopping • concomitant use of NSAID with heparin or other antiplatelets had been a major implicating risk factor for SEH

  25. ADP receptor antagonists (clopidogrel and ticlopidine) • irreversibly block platelet P2Y12 ADP receptors, causing impairment of both the primary and secondary phases of platelet aggregation • Due to the side-effects of aplastic anaemia and thrombotic thrombocytopenic purpura, ticlopidine has been replaced by clopidogrel in most instances

  26. ADP receptor antagonists • The ESC recommends “double” antiplatelet therapy with aspirin and clopidogrel for 9–12 months following non ST-elevation acute coronary syndrome, 6–12 months after drug eluting stent (Silber et al, 2005) • No studies have evaluated the use during CNB • Stop clopidogrel 7d, ticlopidine 10-14d

  27. Glycoprotein (GP) IIb/IIIa antagonists • abciximab, eptifibatide and tirofiban- bind to platelet GP IIb/IIIa receptors • Abciximab - most frequently used drug of this class, t1/2 12 h, complete platelet recovery occurs 48 h after discontinuing the drug • eptifibatide, tirofiban - platelet recovery 4–8 h after stopping

  28. Postoperative management of SEH • Although back pain is reported to be the most common and earliest symptom of SEH (Kreppel et al, 2003), most patients have instead reported sensory-motor deficit of the lower limbs or bowel and bladder dysfunction (Vandermeulen et al, 1994; Horlocker & Wedel, 1998; Moen et al, 2004)

  29. Postoperative management of SEH • investigation of choice - (MRI) (Larsson et al, 1988) • The ultimate treatment is emergency surgical decompression by laminectomy • Local written guidelines should be in place in all hospitals (SIGN 2002)

  30. Postoperative management of SEH • Neurological observation should be performed every 4 h (Meikle et al, 2008) • continue for at least 24 h after catheter removal (Horlocker et al, 2003) • Any motor or sensory deficit that develops during CNB, should be treated as indicative of SEH • the epidural infusion should be stopped immediately (Meikle et al, 2008) • If there is no recovery of neurological symptoms within 4 h an urgent MRI should be performed (Christie & McCabe, 2007)

  31. Postoperative management of SEH • ideally surgery should take place within 8–12 h of developing symptoms (Vandermeulen et al, 1994; Lawton et al, 1995).

  32. summary • The key issue is to balance the risk of VTE on the one hand and the risk of SEH on the other • If CNB is to be performed one must ensure that (i) near-normal haemostasis is restored prior to catheter insertion/removal (ii) post-CNB anticoagulation is carried out neither too early nor too late, so as to avoid SEH and suboptimal thromboprophylaxis, respectively

  33. summary • Paying attention to: the recommended time intervals for the cessation/initiation of the anticoagulants; • careful patient selection; individual risk assessment and pharmacological knowledge are all crucial factors in the safe administration of CNB

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