Card Set Information

2012-06-26 19:30:20
PT3 Antithrombolytics

Antithrombolytics Processes
Show Answers:

  1. Stages of Hemostatis
    • Stage 1—formation of platelet plug
    • Platelet aggregation (want to prevent this during surgery)
    • Stage 2—coagulation
    • Intrinsic system
    • Extrinsic system
  2. Heparin
    • Rapid acting anticoagulant
    • Accelerates binding of Antithrombin III to the clotting factors:
    • --Thrombin
    • --Factor Xa

    • Heparin will not breakdown existing clots. Will only prevent clots from forming. Therefore, give as prophilactic.
  3. Clotting Mecahnism
    • Arteries
    • White clot
    • Platelets
    • Veins
    • Red Clots
    • Fibrin

    • Coagulation cascade
    • intrinsic
    • activated when blood comes in contact with injured vessel wall
    • Extrinsic
    • Activated when vessels walls releases tissue factor--> causes adherence, activation and aggregation of platelets
    • Final common pathway
    • Factor x is acrivated
    • Prothrombin-->thrombin
    • Fibrinogen-->fibrin
  4. High Molecular weight Heparin
    Unfractionated Heparin)
    • Inhibits both thrombin and factor xa
    • uses: treat venous thrombosis ie prevent further formation.
  5. Low Molecular Weight (LMW)
    Enoxaparin  (Lovenox)
    • Inhibits Factor Xa 
    • Has little effect on Thrombin

    • Uses:  Prophalactically after OR to prevent thrombus development
    • Subq: DO NOT give IV or IM
    • Does not require monitoring of PTT (partial thromboplastin time)
  6. Dalteparin sodium
    • Mixture of Heparin sulfate, Dermatan Sulfate and Chondroitin Sulfate (Heparin + antiinflamatory)
    • Derived from porcine intestinal mucosa (contraindicated for pts with allergic rxn or religious intolerence of pork products).
    • Even less inhibition of Thrombin than LMW heparin….but does inhibit Factor Xa
    • Uses:  Prophalactic prevention of post-op thrombus
    • Black Box Warning!: Epidural and Spinal Hematomas. LMW Heparin would be a better choice for such pts.
  7. Heparin
    • Uses
    • PE
    • STroke
    • Vein thrombosis

    • Adverse effects
    • Hemorrage
    • Thrombocytopenia
    • Hypersensitivity rxn.
    • Heparin Induced Thrombocytopenia (HIT)
  8. Heparin Induced Thrombocytopenia (HIT)
    • Immune mediated process
    • Antibodies to heparina and platelets are produced
    • Leads to thrombus formation
    • Indications: DVT, Platelet count less than 100K or 50% below baseline
    • Treatment
    • Direct thrombin inhiitors: do not affect platelets, ie Lepirudin, argatroban
  9. Heparin Nursing Implications
    • Prior to and during  therapy:
    • --CBC
    • --Platelet count
    • --Hgb and Hct
    • --PTT or a aPTT
    • activated Partial thromboplastin time
    • Values 1.5-2.5 times baseline
    • Obtaining specimens

    • Arm band identification
    • For IV use, use an infusion pump and check patency
    • Double check all doses (need 2 RNs)
  10. More nursing implicaitons for Heparin
    • Sub-q dose
    • --Always use stomach, anywhere except 1 inch around umbilius.
    • --Don’t aspirate (pull back on plunger)
    • --Don’t massage. Doing either --> brusing (hematoma)
    • IV
    • Maintain pressure on venapucture sites for ~ 5 minutes to prevent hematomas. Check for epidural and spinal hematomas.

    Antagonist - Protamine sulfate. Antitode for too much heparin when pt can no longer clot at all and keeps on bleeding.
  11. Warfarin (Vitamin K antagonist)
    • Oral anticoagulant
    • Affects synthesis—factors VII, IX, X, 
and prothrombin
    • Peak effect ~ 36-72 hours
    • Duration of action 4-5 days
    • Is highly protein bound
    • Uses:
    • Prevents thrombosis formation
    • Adverse effects
    • Hemorrhage
    • Gingival
    • Occult (bloody poops, sounds demonic-->occult)

    Will be taking concurrently with Heparin until pt can be weened off heparin.
  12. What Lab Values are necessary for Warfarin administration
    • PT  Prothrombin time
    • --Normal 11-13 secs
    • --2-3.5 x baseline

    • INR (International Normalized Ratio)
    • --Normal  0.7 - 1.8
    • --2-3.5 unites

    • Antagonist ~ Vitamin K (found in dark green leafies). Give if INR/PT times are unusually high.
    • Check for bruising and bleeding, esp occult blood

    Always given in afternoon/evening because need a PT level before given, but need a baseline to compare. Baselines should be available my afternoon/evening.
  13. Factor Xa Inhibitor
    (Fondoaparinux Sodium)
    • Antagonizes the action of factor Xa
    • Common Pathway
    • Prevention of DVT in Orthopedic surgical procedures
    • Subq admin
    • Admin 1x/day.
    • No coagualtion testing needed

    Nursing Implications: watch for bleeding.
  14. Rivaroxaban
    • Selectivly inhibits factor Xa
    • Slightly more effective than enoxaparin (LMW Heparin)
    • Taken as a pill
    • Nursing implications: monitor creatinine Clearance prior to beginning
    • Doesn't require lab monitoring, but does alter INR
    • Usually started 6-10 hours after OR and continued for 12 days.
  15. Antiplatelet drugs
    • Aspirin (ASA)
    • Inhibition of cyclooxygenase
    • Ticlopidine (Ticlid) ADP receptor antagonistsTirofiban (Aggrastat) - GP IIb / IIIa receptor antagonists Clopidogrel (Plavix) ADP receptor antagonist. Used as an alternative to ASA.
  16. Direct Thrombin Inhibitors
    • related to Hirudin found in leech saliva
    • Interact directly with thrombin (circulating, clot bound)
    • Used for those with HIT, and only a treatment for HIT because there is no antidote.
    • Monitor aPTT
    • Hgb and Hct
    • There is no antidote.
  17. Dabigatran Etexilate (Indirect thrombin inhibitor)
    • Inhibits thrombin
    • 2x/day oral dosing
    • don't interact with food
    • Should not take with otc meds, nsaids
    • blood tests are not necessary
    • take capsule whole and not given via feeding tube
    • check Cr Cl before giving.
    • Impedes coagulation cascade in a few hours and effects last about 5-9 hrs
    • Risk for MI and GI bleeding
    • Epidural and spinal hematomas
    • there is no antidote
    • Ecarin clotting time (ECT) or aPTT.
    • Proposed as coumadin repacement.
    • Indications: atrial fibrilation--> stroke, MI, DVT, PE.
  18. Teaching Tips for anticoagulants
    • Wear a medic alert bracelet
    • Discuss ways to derease risk of falls
    • Avoid sharp toolsa nd knives. Use an electric razor
    • Regular lab monitoring
    • Contact HCP prior to dental work or surgery
    • Take med at same time every day
    • Possibilityof bleeding
    • Consistent intake of vit K
    • Altered effects of alcohol on INR making INR labs meaningless, so no booze.
    • NO OTC meds, ie no asparin and/or tylenol.
  19. Thromobolytic Drugs
    • Inactivates plasminogen
    • Dissolves thrombi after they form
    • Best results if given early in treatment
    • For MI’s not longer than 6 hours, best if given within an hour of MI.
  20. Thrombolytic Drugs
    Uses and Adverse Effect
    • Uses
    • Myocardial infarction
    • Deep vein thrombosis
    • Massive pulmonary emboli
    • Adverse effects
    • Bleeding
    • Hypotension
    • Fever
  21. Contraindications for Thrombolytics
    • Active internal bleeding
    • Aneurysm
    • Surgery or trauma within past 2 months
    • History of CVA with unknown cause
    • Brain neoplasms
    • Severe, uncontrolled hypertension (>160 SBP)
  22. Pharmakokinetics of thrombolytics
    • Streptokinase
    • Onset ~  immediate
    • Peak ~ 30-60 min
    • Duration ~ 4-12 hrs
    • Alteplase (tPA) (drug of choice)
    • Onset ~  immediate
    • Peak ~ 5-10 min
    • Duration ~ 2.5-3 hrs
    • Reteplase (Retavase)
    • Onset ~  immediate
    • Peak ~ 5-10 min
    • Duration ~ Unknown
    • Half-life ~ 13-16 min

    Need combo therapy along with antihrombolytics beccause thrombolytics treat clots while antithrombolytics prevent them.