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34 Cards in this Set
- Front
- Back
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intrinsic pathway
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– contact of platelets with negatively charged surface eg. collagen.
Slower Factor XII is activated from exposure to collagen Measured by partial thromboplastin time |
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extrinsic pathway
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tissue factor (phospholipid) released from cells of endothelium. (Activates Factor VII)
Rapid Measured by prothrombin time INR |
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diff btw serum and plasma
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-plasma has clotting factors
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NSAIDs inhibit
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Cox-1 – elevates speed of coagulation of the blood. NSAIDs Inhibit formation of thromboxine A1
Cox 2 – inflammation |
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Clopidogrel (Plavix), Ticlopidine (Ticlid), Dipyrimadole (Persantine) are types of
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-antiplatelets
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Antiplatelet drugs are used to:
prevent, during, or after ______ during _____ surgeries prevention of _____ or _____ also (2) |
-MI
-angioplasty, stenting -stroke, TI -unstable angina, atrial fibrillation |
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Laboratory Tests to Monitor the Effects of Antiplatelet Drugs (2)
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1) Ivy Bleeding time: small injury, measure time bleeding continues (normally 1-6, 7 minutes)
2) Platelet function analyzer: measures time of platelet clot w/I a capillary tube. (normally 60-120 seconds) |
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Local Measures to Control Post-op bleeding (5)
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- Careful, atraumatic surgical technique
- Hemostatic agent in the socket (Gelfoam, Avitine, Surgicel) - Careful suturing - Post op pressure packs (damp gauze for 30-60 minutes); esp impt for flap compression - Antifibrinolytic agents. (tranexamic acid [Cyclokapron Oral] or epsilon amino caproic acid [Amicar] as a mouthwash or to soak pressure gauzes. |
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Use of anticoagulants:
presence of ______ history of ______ reduce risk of ________ maintain patency of _______ prophylaxis to prevent post-operative _______ also (3) |
-mechanical prosthetic heart valves
-deep vein thrombosis (DVT) -recurrent MI -arterial lines (heparin) -DVT (heparin and derivatives) -pulmonary embolism, ischemic stroke, atrial fibrillation |
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2 grps of anticoagulants
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-heparin/heparin based
-warfarin (coumadin): vita K antagonist |
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bivalirudin (3)
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-direct thrombin inhibiting anticoagulant
-related to "hirudin," a natural component of leech saliva -reversible inhibitor |
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Fondaparinux (2)
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-anticoagulant
-specific factor XA inhibitor |
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_____ acts rapidly and is used in acute situations
______ is used in chronic situations, for prevention and prophylaxis (anticoagulants) |
-Heparin
-Warfarin |
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Warfarin:
structure metabolized action 1/2 life delay of onset antidote increased effect when mixed w/ (7) |
-vita K analogue
-liver -interferes w/ synth of VII, IX, X, prothrombin -36hrs -8-12hrs -Vita K -antibiotics, aspirin, NSAIDs, antifungals, tramadol, tricyclics, certain herbs |
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what enzyme is sensitive to warfarin
function? |
-epoxide reductase
-When K is oxidized, decarboxylated prothrombin becomes prothrombin. ER enzyme takes the oxidized vit K to the reduced, to restart the cycle |
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Warfarin is also inactivated in liver by
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-cytochrome P450
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Warfarin pharmacokinetics:
rapidle absorbed when _______ highly ______ crosses/does not cross placenta? breast feeding? 1/2 life clearance clearance dependent on effectivity ranges due to |
-orally admin
-protein bound in plasma -yes, crosses. Teratogenic -breast feeding OK -24-60hrs -variable but usually slow -hepatic P450s (esp 2C9) -genetics. VKORC1 haplotypes. |
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Warfarin dosage:
european african american asian |
-5mg/d
-6-7mg/d -3-3.5mg/d |
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lab tests to monitor warfarin/coumadin activity (2)
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1) Prothrombin time:
– measures rapid phase, root of coagulation -Take a sample of pt’s blood, add the Thromboplastin reagent, calculate time required to form a clot (seconds). 2) INR: - INR= (PT obs/PT control)^ISI -normal = 1 -Normal PT ratio is 1. |
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INR:
theraputic target target for prosthetic heart valves |
-2.5 (2-3)
-2.5-3.5 |
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Factors that can influence INR (9)
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-Drug Interactions
Diet Body gets Vitamin K from the intestinal flora (alteration may Increase INR) Fever (Increase INR) Hepatic failure (increase INR) Thyroid Function (hypo decrease INR, hyper increase INR) Stress (increase INR) Smoking (may decrease INR) Noncompliance (increase or decrease of INR) |
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Risk:
low INR high INR |
-ischemic stroke
-intracranial bleeding |
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why does warfarin interact w/ some foods
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-foods w/ lots of vita k can interfere w/ drug action
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effect of antibiotics and antifungals on warfarin (2)
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-inhibit metabolism by P450 cytocrome CYP2C9
-can decrease drug's metabolism, thereby increasing its effect. |
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comorbid conditions that increase bleeding w/ warfarin (6)
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-Liver
-Kidney -Tumor -Bone marrow failure -Chemotherapy -Autoimmune diseases |
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sign of warfarin overdose
reversal of anticoagulants: INR<5, no bleeding: INR>5, no bleeding: INR>9: serious bleeding: |
-unusual bleeding
-lower, omit dose -omit 1-2 doses, +/- 2.4mg of oral vita K -3-5mg of vita K -FFP, slow IV admin of 10mg vita K |
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warfarin bleeding risk:
%s when high-risk (4) |
-9% total, 0.6% fatal
-most likely in first 3 months -death usually intracranial bleeding -pts>70, htn, GI ulcer, serious comorbidity |
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Vitamin K applied as Antidote (4)
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• 2.5mg PO will correct w/I 24-48 hours
• Bigger doses not better, can cause prolonged warfarin resistance • 0.5-1mg IV will correct in 24 hours (may be a good option prior to invasive procedures) • 10mg IV will correct w/I 6-12 hours, but will have to start all over with heparin/bridge therapy |
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Topical Hemostatic Adjuncts (7)
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-Absorbable gelatin (Gelfoam)
-Oxidized cellulose (Surgicel) -Microfibrillar bovine collagen (Avitene) -Topical thrombin preparations -Antifibronolytics (Amicar) -Astringents -Vasoconstrictor |
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types of astringents (4)
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-Ferric sulfate (Astringedent)
-Aluminum chloride (Hemodent) -Aluminumpotassium sulfate (generic) -Aluminum sulfate (Gel-Cord) |
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Antifibrinolytic Mouthrinses (2)
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1) Epsilon amino caproic acid (Amicar):
-Inhibits fibrinolysis of already formed clot -Syrup (1.25 gm/5cc), 5-10ml QID for 7 days -mouthwash or soak pressure gauze. 2) Tranexamic acid (Cyklokapron): -mouthwash for 2 min, QID, for 7 days -unfortunately 4.8% is not FDA approved in USA. |
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additional post-op measures (2)
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-Tylenol, Codeine, Celebrex for pain
-Avoid drugs and herbals that may increase bleeding |
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for continued bleeding (3)
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-25% amicar soaked gauze pressure pack
-intranasal desmopressin acetate (DDAVP) spray: 2.5 ml bottle, 2 nostril sprays BID for 1-2 days. Stimulates the release of factor VIII and vW Factor -Vitamin K (phytonadione, AquaMEPHYTON) 2.5-25mg iv, im, sc, or oral |
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INR range acceptable for dental procedures
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- 2.6-5
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