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Definition :

Definition Anticoagulants are drugs used to prevent clot formation or to prevent a clot that has formed from enlarging. They inhibit clot formation by blocking the action of clotting factors or platelets.

Types of anticoagulants :

Types of anticoagulants Inhibitors of clotting factor synthesis: Inhibit the production of certain clotting factors in the liver, e.g. warfarin (Coumadin; Vitamin K antagonists) Inhibitors of thrombin: Interfere with blood clotting by blocking the activity of thrombin, e.g. heparin, lepirudin ( Refludan ) Antiplatelet drugs: Interact with platelets, to block these from aggregating into harmful clots, e.g. aspirin, ticlopidine ( Ticlid ), clopidogrel ( Plavix ), tirofiban ( Aggrastat ), andeptifibatide ( Integrilin )

Reason to use:

Reason to use Routine thromboprophylaxis High risk patients Ischemic heart disease Valvular heart disease Angioplasty or valve replacement Thrombolysis DVT Known TE Stroke

Risk Of Thromboembolism:

Risk Of Thromboembolism Nearly all hospitalized patients have at least one risk factor 40% of patients have 3 or more risk factors ( Geerts et al, as cited by the 2010 ASRA statement)

Risk Factors for VTE :

Risk Factors for VTE Surgery Trauma (major trauma or lower extremity injury) Immobility, lower extremity paresis Cancer (active or occult) Cancer therapy (hormonal, chemotherapy, angiogenesis) Venous compression (tumor, hematoma, arterial abnormality) Previous VTE

Risk Factors for VTE :

Risk Factors for VTE Increasing age Pregnancy and the postpartum period Estrogen-containing oral contraceptives or hormone replacement therapy Selective estrogen receptor modulators Erythropoiesis -stimulating agents Acute medical illness Inflammatory bowel disease

Risk Factors for VTE :

Risk Factors for VTE Nephritic syndrome Myeloproliferative disorders Paroxysmal nocturnal hemoglobinuria Obesity Central venous catheterization Inherited or acquired thrombophilia

Common drugs affecting coagulation:

Common drugs affecting coagulation DRUG USE Aspirin Thromboprophylaxis in coronary artery disease NSAIDs Analgesics used widely in arthritis Clopidogrel Antiplatelet used in coronary artery disease Warfarin Thromboprophylaxis in atrial fibrillation, post heart valve replacement, DVT, or pulmonary embolism Unfractionated heparin Thromboprophylaxis , therapeutic anticoagulation Low molecular weight heparin Thromboprophylaxis , therapeutic anticoagulation Fondaparinux Thromboprophylaxis

Levels of TE Risk and Recommended Thromboproph in Hosp Pts :

Levels of TE Risk and Recommended Thromboproph in Hosp Pts Levels of Risk Approx DVT Risk w/o Thromboproph %* Suggested Thromboprophylaxis Options Low risk minor surgery in mobile patients medical patient who are fully mobile <10 No specific thromboprophylaxis Early and ‘ aggressive’ ambulation Moderate risk most general, open gynecologic or urologic surgery patients medical patients, bed rest or sick moderate VTE risk plus high bleeding risk 10-40 LMWH(at recommended does), LDUH 2 times/d or 3 times/d, fondaparinux High risk hip or knee arthoplasty , hip fracture surgery major trauma, spinal cord injury high VTE risk plus high bleeding risk 40-80 LMWH ( at recommended doses), fondaparinux , oral vitamin K antagonist( INR 2-3) Mechanical thromboprophylaxis *rates based on objective diagnostic screening for asymptomatic DVT in patients not receiving thromboprophylaxis

Previous thromboprophylaxis guidelines:

Previous thromboprophylaxis guidelines Dextran Adjusted-dose standard heparin (approximately 3500 U every 8 hrs) Warfarin (started 48 hrs postoperatively to achieve a prothrombin time [PT] 1.25-1.5 x baseline), or Dextran plus intermittent pneumatic compression (IPC)

Current guidelines:

Current guidelines Low-molecular weight heparin (LMWH) Fondaparinux (2.5 mg started 6-24 hrs postop ) Warfarin (started before or after operation with a mean target INR of 2.5) Continued after hospital discharge for a total of 10-35 days ACCP-NHLBI National Conference on Antithrombotic Therapy. American College of Chest Physicians and the National Heart, Lung and Blood Institute. Chest . 1986;89:1S-106S.

PowerPoint Presentation:

“Therefore, although thromboembolism remains a source of significant perioperative morbidity and mortality, its prevention and treatment are also associated with risk” (2010 ASRA statement, page 67).

PowerPoint Presentation:

Neuraxial techniques improve mortality, major morbidity, and patient-oriented outcomes Particularly epidural anesthesia and continued epidural analgesia Attenuation of the hypercoagulable response and the associated reduction in the frequency of thromboembolism 1. Capdevila X, Barthelet Y, Biboulet P, Ryckwaert Y, Rubenovitch J, d'Athis F. Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology . 1999;91:8-15. 2. Liu S, Carpenter RL, Neal JM. Epidural anesthesia and analgesia. Their role in postoperative outcome. Anesthesiology . 1995;82:1474-1506.

Regional interventions:

Regional interventions Spinal analgesia Single shot epidural Epidural with indwelling catheter insertion Epidural with indwelling catheter removal Plexus blocks Field blocks Nerve blocks

Incidence of neurologic dysfunction:

Incidence of neurologic dysfunction >1 in 150,000 epidural >1 in 220,000 spinal anesthetics recent epidemiologic surveys suggest that the frequency is increasing and may be as high as 1 in 3000 in some patient populations Horlocker TT, Wedel DJ. Anticoagulation and neuraxial block: historical perspective, anesthetic implications, and risk management. Reg Anesth Pain Med . 1998;23:129-134. Moen V, Dahlgren N, Irestedt L. Severe neurological complications after central neuraxial blockades in Sweden 1990-1999. Anesthesiology. 2004;101:950-959. Vandermeulen EP, Van Aken H, Vermylen J. Anticoagulants and spinal-epidural anesthesia. Anesth Analg . 1994;79:1165-1177.

Increased incidence:

Increased incidence Age Associated abnormalities of the spinal cord or vertebral column Presence of an underlying coagulopathy Difficulty during needle placement, and An indwelling neuraxial catheter during sustained anticoagulation

RA Practice guidelines:

RA Practice guidelines Second Consensus Conference on Regional Anesthesia and Anticoagulation in 2002 Convened by American Society of Regional Anesthesia and Pain Medicine (ASRA) Third Consensus Conference on Regional Anesthesia and Anticoagulation in 2009 Published in the ASRA Journal; January-February 2010 issue Guidelines by American Society of Chest Physicians

PowerPoint Presentation:

American Society of Regional Anesthesia Second Consensus Conference on Neuraxial Anesthesia and Anticoagulation April 25-28, 2002 Regional Anesthesia in the Anticoagulated Patient: Defining the Risks Introduction Numerous studies have documented the safety of neuraxial anesthesia and analgesia in the anticoagulated patient. Patient management is based on appropriate timing of needle placement and catheter removal relative to the timing of anticoagulant drug administration. Familiarity with the pharmacology of hemostasis -altering drugs, the clinical studies involving patients undergoing neuraxial blockade while receiving these medications, as well as the case reports of spinal hematoma will guide the clinician in management decisions. Second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation. Regional Anesthesia & Pain Medicine. 28(3):172-97, 2003 May-Jun.

PowerPoint Presentation:

“Therefore, although thromboembolism remains a source of significant perioperative morbidity and mortality, its prevention and treatment are also associated with risk” (2010 ASRA statement, page 67).

Patient receiving thrombolytic therapy:

Patient receiving thrombolytic therapy No lumbar punctures and neuraxial anesthesia Avoid thrombolytic therapy for 10 days if these procedures have been performed (evidence Grade 1A) Neuraxial blocks at or near the time of fibrinolytic and thrombolytic therapy: Neurological monitoring every 2 hours or less “for an appropriate interval”. If epidural catheter present avoid drugs producing sensory and motor block to facilitate neurological assessment (Evidence Grade 1C) Measure fibrinogen levels for appropriate timing of catheter removal (Evidence Grade 2C).


UFH 5000 U of UFH twice daily do not have contraindication for neuraxial techniques >4 days (heparin-induced thrombocytopenia) should have a platelet count before neuraxial block and catheter removal Delay heparin administration for 1 hr after needle placement Remove catheter 2-4 hr after the last heparin dose; re-heparin 1 hr after catheter removal Monitor the patient postoperatively to provide early detection of motor blockade. Avoid local anesthetics through catheter


LMWH Anti- Xa level is not predictive of the risk of bleeding (Grade 1A) RA at least 12 hr after the LMWH last standard dose (Grade 1C); 24 hr if higher doses Postop : Twice-daily dosing; start 24 hrs postop . Remove EpiCaths 2 hr before the dose Single-daily dosing; 6-8 hrs EpiCaths removed a minimum of 10-12 hrs after the last dose

Oral anticoagulants:

O ral anticoagulants Warfarin must be stopped 4-5 days prior to the procedure and the INR measured before a neuraxial Neuraxial catheters should be removed with an INR of less than 1.5 block (Grade 1B) Measure INR, sensory / motor function daily Minimise LA dose No cath removal if INR>3

Antiplatelets medications:

Antiplatelets medications NSAIDs seem to present no added significant risk of spinal bleeding related to neuraxial techniques Waiting period between discontinuation of a drug and neuraxial block is: Ticlopidine : 14 days; Clopidogrel : 7 days. Normalization of platelet function should be documented. Platelet GP IIb / IIIa inhibitors; Neuraxial techniques should be avoided until platelet function has recovered. Abciximab : 24-48 hrs; Eptifibatide and tirofiban : 4-8 hrs

CNB in patients taking drugs:

CNB in patients taking drugs DRUG RECOMMENDATION Aspirin & NSAIDs No contraindication Clopidogrel Stop 7 days preoperatively Unfractionated heparin Subcutaneous give 4 hours before or > 1 hour after block Intravenous: stop 4 hours before block. Give > 1 hour after block. Remove catheters 2-4 hours after dose Low molecular weight heparin Wait 12 hours after dose or give drug 2 hours after block Wait 24 hours after therapeutic dose Warfarin INR ≤ 1.5


Conclusion A good pre-anesthetic or pre-procedure history is always beneficial You can’t always memorize whole of the pharmacology; it’s ever changing When in doubt, consult pharma guides and/or product inserts Its always better to be on the safer side



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