Anticoagulation and Neuraxial Anesthesia Dr. Daniels

Thromboprophylaxis and Neuraxial Anesthesia Don Daniels, M.D. Chief Anesthesiologist Brooke Army Medical Center Fort Sam Houston, TX Thromboprophylaxis and Neuraxial Anesthesia • OBJECTIVES – Discuss surgical indication for anticoagulation – Define surgical vs anesthesia risk/concerns – Discuss various anticoagulation methods – Discuss anesthesia options to minimize risk Thromboprophylaxis and Neuraxial Anesthesia • Perioperative hypercoagulability: – Deep vein thrombosis • incidence = 25-70% • local chronic pain, swelling & skin ulceration – Pulmonary embolism • Fatality = 0.1-7% • Chronic thromboembolic pulmonary HTN rare Thromboprophylaxis and Neuraxial Anesthesia • Patients at risk of DVT & PE – – – – – – – – – – – – – Advancing age Type of operation Duration of operation Prior thromboembolism Malignancy Varicose veins Obesity Immobility/Neurologic disease Myocardial infarction Low cardiac output Major trauma Oral contraceptives Hemostatic abnormalities • Surgeries at risk of DVT & PE – Major abdominal operations – Hip or knee arthroplasty – Multiple trauma patients Thromboprophylaxis and Neuraxial Anesthesia • Prevention of venous thromboembolism – Antithrombotic drugs – Inhibition of platelet function – Prevention of lower extremity venous pooling with mechanical devices – Neuraxial anesthesia – Early ambulation Thromboprophylaxis and Neuraxial Anesthesia: Mechanical Devices • Intermittent pneumatic compression of the calves equal to LDH for knee surgery • Not as effective in hip surgery Thromboprophylaxis and Neuraxial Anesthesia: Anesthesia technique & early ambulation • Regionals in hip surgery reduce incidence of DVT by 50% in pts not receiving thromboprophylaxis • Combination of regional with thromboprophylaxis does not provide any greater DVT protection than thromboprophylaxis alone. 29 vs 16% • Early ambulation is a valuable DVT prophylactic measure Thromboprophylaxis and Neuraxial Anesthesia: 1999 ASA Closed Claims Analysis • 60/4183 (1.4%) claims resulted in para (45) or guadriplegia (15) • Most common causes epidural hematoma, chemical injury, anterior spinal artery syndrome and meningitis • 35 lumbar epidurals, 9 SAB, 4 thoracic epidural accounted for 48/60 • Major factor in 13/48 was systemic anticoagulation • All 13 received intraoperative IV heparin, 5 continued to get heparin post op • 11 epidural hematomas occurred after lumbar epidural, 2 after SAB • 10 diagnosis delayed, post op care judged inappropriate, median payment $447,381 Thromboprophylaxis and Neuraxial Anesthesia • Heparins – Inactivate coagulation enzymes by binding to antithrombin III Thromboprophylaxis and Neuraxial Anesthesia: Low Dose Heparin (LDH) • Surgical – DVT reduced by 70% – PE reduced by 4050% – Risk of increased surgical bleeding = 66% – Risk of transfusion <2% • Anesthesia – Neuraxial anesthesia considered relative contraindication Thromboprophylaxis and Neuraxial Anesthesia: Heparin after regional. How safe? • Rao & El-Etr 4461 LEA w/o sequela • Sage 7000 LEA w/o sequela • Scherer 1071 TEA w/o sequela • 1:150,000 following epidural • 1:220,000 after spinal Thromboprophylaxis and Neuraxial Anesthesia: SQ Heparin prior to block. Is this safe? • Lowson & Goodchild - 5000 U SQ 2 hr prior to neuraxial block is safe • Similar results noted by Orthopedic surgeons and general surgeons • Caution: 3 case reports of spinal hematoma Thromboprophylaxis and Neuraxial Anesthesia: Identification of Risk Factors with Standard Heparin • Presence of blood during needle/catheter placement • concomitant aspirin therapy • heparinization within 1 hr Guideline for use of Neuraxial Anesthesia in Patients Receiving SQ or Low Dose Heparin • Spinal: – Considered safe 4 hrs after dose – Withold redose of heparin for 2 hrs after block • Epidural: – Get PTT before placement, any manipulation or removal of catheter – Considered safe 4 hrs after dose – Heparin redose at least 2 hrs after ndl or cath placement, manipulation or removal of cath Thromboprophylaxis and Neuraxial Anesthesia: Low molecular weight heparin (LMWH) • Unable to acclerate inactivation of thrombin by AT III • Catalyze the inhibition of Factor Xa by AT III • Does not prolong aPTT • Low protein binding prolongs the plasma half life • As effective as LDH in stopping DVT/PE Thromboprophylaxis and Neuraxial Anesthesia: LMWH. Is this safe? • Wolf 9006 pts - no neurologic sequela (1993) • Bergvist review 44 reports (8231 pts) - no neurologic sequela (1992) • Pham 1025 pts - no neurologic sequela (1994) Thromboprophylaxis and Neuraxial Anesthesia: LMWH. Is this safe? • • • • • 1994 - 1 case of neuraxial hematoma 1995 - 11 cases of neuraxial hematoma 1997 - 30 cases of neuraxial hematoma April 1998 - >40 cases Fall 1998 - BAMC orthopedic surgeons unaware of danger of LMWH & neuraxial anesthesia Thromboprophylaxis and Neuraxial Anesthesia: Identification of Risk Factors with LMWH • 75% of patients were elderly women • Multiple or difficult needle placement • Concomittant administration of an additional drug affecting coagulation • Preop administration of LMWH or within 12 hrs of needle placement • Variability of presenting signs, symptoms and timing Recommendations for Patients receiving LMWH and Neuraxial Anesthesia • Monitoring of anti-Xa is not recommended • Think twice about neuraxial placement when antiplatelet or oral anticoagulant meds are used in combination with LMWH • Delay LMWH 24 hrs if blood noted during ndl or cath placement • A single dose SAB 10-12 hrs after dose may be safer in pts who received preop LMWH • Remove cath before initiation of postop LMWH • If LMWH and continous epidural planned together, use opioid or dilute local anesthesia and be vigilant • Cath removal should be 10-12 hrs after dose LMWH. Subsequent dosing of LMWH should be delayed until 2 hrs after cath removal. Thromboprophylaxis and Neuraxial Anesthesia: Oral Anticoagulants • • • • Block regeneration of Vitamin K Close laboratory monitoring needed Optimal PT range 1.3-1.5 times normal Risk of increased bleeding above 1.7 times normal Oral Anticoagulants and Neuraxial Anesthesia • Several case reports of neuraxial hematomas • Variability of response to warfarin • Close monitoring of coag status when spinal or epidural cath used postop • Prior to removal of cath coag status should be determined Guideline for use of Neuraxial Anesthesia in Patients Receiving Coumadin • Spinal: – Place within 6-8 hrs after preop dose – PT required morning of surgery • Epidural: – Place within 6-8 hrs after preop dose – PT required morning of surgery – Remove catheter morning after surgery (POD #1) – PT required morning of catheter removal – Neuro checks q 1 hr for next 12 hrs following cath removal – If INR >1.5, anticoagulation must be reversed prior to removal of catheter Thromboprophylaxis and Neuraxial Anesthesia: Aspirin/NSAIDs • Inhibit enzyme cyclooxygenase, reducing thromboxane A2 production • Prostacyclin generation capacity minimally affected by low dose ASA regimens while completely blocked by larger doses • Prostacyclin inhibition short lived in NSAIDs, lifetime of platelets with ASA • Incidence of DVT/PE reduced with antiplatelet drugs but not as much as LDH/LMWH Antiplatelet Drugs and Neuraxial Anesthesia: Is it safe? • Minor hemorrhagic events such as blood aspirated through needle • No patients reported with neuraxial hematoma Guideline for use of Neuraxial Anesthesia in Patients Receiving Aspirin or NSAIDs • Neuroaxial anesthesia may be offered • Do not offer if patient taking other anticoagulant therapies • Do not offer if patient has pre-existing coagulopathy Neuraxial Hematoma • Signs may be missed, masked or ignored • If suspected, CT or MRI immediately • Decompressive laminectomy within 12 hrs Thromboprophylaxis and Neuraxial Anesthesia: Summary • Perioperative risk of DVT/PE is high • Perioperative risk of neuraxial hematoma is low but an ever present danger • Understanding danger of anticoagulation and neuroaxial anesthesia helps minimize risk