Regional Anaesthesia and Thromboprophylaxis

1. Regional Anaesthesia and Thromboprophylaxis Dr Kate Fogg Royal Brompton Hospital

2. Regional Anaesthesia Epidural/spinal Risks/benefits • Thromboprophylaxis s/c heparin (unfractionated/LMWH) anti-Xa or direct thrombin inhibitors antiplatelet agents warfarin systemic heparinisation Can you put the two together or should you stop one in order to perform the other?

3. Regional blocks • Drug administered directly to the spinal cord to locally block afferent and efferent nerve input. • Usually for major thoracic, abdominal and lower limb surgery • Local anaesthetic +/- opiates

5. Spinal • Dural puncture • Single shot usually • 24-26G needle, pencil point • Less traumatic • Catheter rarely

6. Epidural • Larger needle – 16 G • Loss of resistance technique • Epidural vessels • Usually a catheter technique • Trauma may be on insertion or removal of catheter

7. Benefits • Improved analgesia, greater mobility, fewer opiate side-effects • Decrease stress response adverse cardiac, pulmonary and immune outcomes hypercoagulable state • Decrease troponin release in cardiac patients • ? Does this translate into clinical benefit

8. Most impressive in high-risk patients undergoing major surgery • Decrease blood loss and transfusion requirement • Decrease thromboembolic complications • Decrease pneumonia and resp depression • Decrease MI and ARF • Decrease mortality

9. Risks • Failure • Dural Tap • Catheter migration subdurally • Nerve damage • Epidural abscess • Epidural Haematoma

10. Haematoma • Rare but potentially catastrophic • Tryba (1993) – 1:150,000 epidural anaesthetics, 1:220,000 spinals (review 1.5 million patients) Risk probably higher if on drugs altering coagulation • Vandermeulen (1994) review for case reports of haematoma • 75% associated with epidural, 25% spinal • 87% coagulation abnormalities/technical difficulties • Coag abnormalities include alcohol abuse, CRF, thrombocytopaenia as well as drugs

13. Symptoms • Sharp back pain • New motor/sensory loss • Urinary retention • Variable and may be confused with effect of LA • Paraplegia • Need surgery within 8 hrs to get good or partial recovery.

14. Putting the two together? • 1993 LMWH in USA b.d unlike in Europe o.d –sudden increase in reports of haematoma. • American Society of Regional anaesthesia and Pain Medicine – Consensus Statement ,2002 • German Society of Anaesthesia and Intensive Care Medicine 2004

15. Unfractionated heparin • Vascular or cardiac cases • Avoid if other coagulopathy • Heparin delayed for 1hour after needle placement • Catheter removal 2-4 hr after last heparin • Post-op monitoring for at least 48 hrs

16. Cardiac • Does the benefit outweigh the risk? • Can show less troponin release • Consistent decrease in ventilator time • Better analgesia on day 1 • ?fewer pulmonary complications • No consistent improvement in arrythmia/cardiac/renal/neurologic outcome • No effect on mortality

17. Recent case reports of haematomas • Can achieve other benefits with beta blockers/multimodal analgesic techniques • ?only in high risk COPD patients or those elderly at high risk of confusion

18. LMWH • Dose dependent antithrombotic effect by anti-Xa inhibition • Anti-Xa level not predictive of bleeding • Beware antiplatelet or oral anticoagulant • Needle placement 10-12 hours after last dose LMWH • Higher dose….wait 24hrs

19. Post-op: • Catheter technique safe • B.D dosing; remove catheter beforehand. Wait 2hrs after catheter removal before first dose • O.D. can have indwelling catheter. Remove minimum of 10-12 hours after last dose. Subsequent dose minimum 2hrs later

20. Oral anticoagulants • Stop 4-5 days before • PT/INR within normal limits • If on low dose post-op need to monitor INR daily • Catheter removal when INR<1.5

21. Antiplatelet medications • Include: aspirin, NSAIDs, thienopyridine derivatives (ticlodipine/clopidogrel), GP IIb/IIIa antagonists (abciximab/tirofiban) • GPIIb/IIIa in acute coronary syndrome….unlikely to be heading for surgery where epidural needed • No wholly accepted test to guide antiplatelet therapy • CLASP study in obstetric patients – aspirin alone does not increase risk • NSAID alone no increased risk

22. Actual risk of haematoma with clopidogrel etc unknown. • Based on half-lives etc… • Stop ticlodipine 14 days, clopidogrel 7 days • GPIIb/IIIa contraindicated with 4 weeks • Beware concurrent medications

23. Little evidence increased surgical bleeding in non-cardiac studies • ? Stop only to make epidural safer (continue aspirin) • Usually on aspirin + clopidogrel because of intracoronary stent

24. Drug eluting stents • Stop intimal hyperplasia which leads to early occlusion • Delay epithelialisation – hence need long term antiplatelet Rx • Stopping antiplatelet Rx before surgery may increase risk of infarct (combine hypercoagulable state+ poorly endothelialised stent) • Weigh benefit of epidural (and lesssurgical bleeding) v ischaemia/infarct • ? Combine the two ? After platelet function

25. ? Plateletfunction monitoring • Spectrum of response to Rx • Can we identify which patients are higher risk? • Bleeding time • Optical light transmission aggregometry • Platelet function analyser • Modified TEG (Agarwal; Anaesthesiology 2006)

26. Anti Xa fondaparinux • Synthetic pentasaccharide, pure anti Xa • 15hr half life • Less venous thromboembolic events than with LMWH in orthopaedic patients • Increased bleeding • Administered post-op (6hrs) • No studies with indwelling epidural catheters • Haematoma risk unclear

27. Thrombin inhibitors • Recombinant hirudin dreivatives. • Inhibit free and clot bound thrombin • Argatobatran (L arginine derivative) similar action • No case reports spinal haematoma • Reports of spontaneous intracerebral bleed • No risk assessment statement given!

28. For each individual patient a clear drug history is needed, an assessment of medical and surgical risk for their procedure, and an assessment of the additional benefit of a regional anaesthetic technique versus the risk of an epidural haematoma. In every patient undergoing a regional technique, rigorous post-op neurological monitoring is essential.

29. Questions?