Anticoagulation and Regional anesthesia

1. Anticoagulation and Regional anesthesia R3 이동현

2. Why regional anesthesia?For joint replacement and hip fracture surgery • Better outcomes by regional rather than general anesthesia in THR, TKR, hip fracture surgery(HFS) (meta-analysis by Rodgers) • One-third fewer myocardial infarctions • 59% reduction in respiratory depression • Pulmonary embolism(PE) – leading cause of death in THR • PE related mortality can be reduced by regional anesthesia

3. Why need to anticoagulateall joint replacement and hip fracture surgery • Without anticoagulation • Post-op DVT ; 36-84% following THR, TKR, HFS • Without DVT prophylaxis • Fatal PE ; 12.9% following HFS • Therefore peri-operative anticoagulation is needed.

4. Risks of epidural hematomaA synopsis of the Vandermeulen findings • Conditions that alter coagulation profile • Thrombocytopenia, hepatic dysfunction, renal insufficiency, another anticoagulant or platelet altering agent • Difficult and/or bloody needle placement • Multiple punctures • Pregnancy • Anatomic abnormalities such as spinabifida oculta or vascular tumor • Epidural catheter placement and removal

5. Unfractionated Heparin(UH) • 5000 units s.c. every 8-12 hrs • With this protocol aPTT remains within normal range • ASRA guidelines for low dose s.c. UH (5000 units s.c. 2hrs before surgery) • Avoid in patients with other coagulopathies • After needle placement ; delay haparin for 1 hr • Catheter removal • 1 hr before subsequent heparin • 2-4 hrs after last heparin • Monitor the patient for early detection of spinal hematoma • If bloody or difficult needle placement • May increase risk • But no data to support mandatory cancellation of a case • Clinical judgment is needed and full discussion with surgeon

6. Unfractionated Heparin(UH) • ASRA guidelines for full dose UH (20,000 – 30,000 units IV) • Currently, insufficient data and experience • If systemic anticoagulation begun with epidural catheter in place ; delay catheter removal for 2-4 hrs after stop anticoagulation • 558 cardiac surgery patients with full anticoagulation (reported by Sanchez and Nygard in 1998) • Place epidural catheter the day prior to the surgery • Limiting attempts to two attemps • Zero incidence of spinal hematoma

7. Low Molecular Weight Heparin(Enoxaprin) • Dosing regimens • US ; 30 mg s.c. every 12 hrs • Europe ; 40 mg s.c. per day • Much lower incidence of epidural hematoma than US protocol • ASRA guidelines • If blood during needle placement ; delay LMWH initiation for 24 hrs after surgery • Combination of other anticoagulant medication may increase risks of hematoma • In European protocol (40 mg/d SC) • Needle placement and catheter removal ; at least 10-12 hrs after the last dose • Subsequent dosing at least 2 hrs after catheter removal • If dosing 2hrs before surgery, avoid neuraxial technique

8. Low Molecular Weight Heparin(Enoxaprin) • In US protocol (30 mg/12hrs) • 1st dosing at least 24 hrs after op. • Catheter removal prior to initiation of dosing • 1st dosing at least 2 hrs after catheter removal

9. Fondaparinux (FONDA) • Selective factor Xa inhibitor • Dose ; daily 2.5 mg SC • 1st dose ; 6-8 hrs after surgery • ASRA guideline • Extreme caution and further clinical experience is needed • Single needle pass, atraumatic needle placement, avoidance of indwelling cathether • If not possible ; use alternate prophylaxis

10. Vitamin K antagonist(warfarin) • Inhibit Vit K dependent factor (II, VII, IX, X) • Onset ; within 24 hrs • Anticoagulation effect last for 72-96 hrs • Also result in depletion of anticoagulation proteins (protein C, protein S) • Therefore must keep in mind during 1st 24-48 hrs ; may actually thrombogenic effect • If urgent or emergent surgery of fully oral anticoagulant patient • FFP, Vit K, prothrombin complex administration • INR should be 1.5 or less before surgery or neuraxial block

11. Vitamin K antagonist(warfarin) • ASRA guideline • Dosing must be stopped (ideally 4-5 days prior to the planned procedure) and PT/INR should be 1.5 or less prior to block • Catheter should be removed when INR is < 1.5

12. NSAIDs and other antiplatelet medications • NSAIDs • ASRA guidelines • Cox-1 inhibitors ; no added risk • Cox-2 inhibitors ; minimal effect, quite safe • Antiplatelet drugs • Ticlopidine(Ticlid), clopidogrel(Plavix) • ASRA guidelines • Ticlopidine ; stop 14 days prior to surgery • Clopidogrel ; stop 7 days prior to surgery

13. NSAIDs and other antiplatelet medications • Platelet glycoprotein IIb/IIIa antagonists • Abciximab, Eptifibatide, Tirofiban • ASRA guidelines • Abciximab ; stop 48 hrs prior to surgery • Eptifibatide, tirofiban ; stop 8 hrs prior to surgery

14. Management of spinal/epidural hematoma • Presenting signs and symptoms • Sudden onset of numbness, weakness or radicular pain • Muscle weakness ; 1st neurologic Sx. In 46% of spinal hematoma • Immediate MRI if new onset neurologic deficit • Immediate surgical decompression if hematoma on MRI • Decompression within 8 hrs after Sx develop ; 77%(10/13) good or partial recovery • Tx delayed for more than 24 hrs ; only 15%(2/12) good recovery (reported by Vandermeulen and associates)