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Stages of Hemostatis
- Stage 1—formation of platelet plug
- Platelet aggregation (want to prevent this during surgery)
- Stage 2—coagulation
- Intrinsic system
- Extrinsic system
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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.
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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
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High Molecular weight Heparin
Unfractionated Heparin)
- Inhibits both thrombin and factor xa
- uses: treat venous thrombosis ie prevent further formation.
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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)
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Dalteparin sodium
(fragmin)
- 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.
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Heparin
(all)
- Uses
- PE
- STroke
- Vein thrombosis
- Adverse effects
- Hemorrage
- Thrombocytopenia
- Hypersensitivity rxn.
- Heparin Induced Thrombocytopenia (HIT)
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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
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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)
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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.
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Warfarin (Vitamin K antagonist)
(Coumadin)
- 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.
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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.
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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.
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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.
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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.
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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.
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Dabigatran Etexilate (Indirect thrombin inhibitor)
Pradaxa
- 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.
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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.
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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.
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Thrombolytic Drugs
Uses and Adverse Effect
- Uses
- Myocardial infarction
- Deep vein thrombosis
- Massive pulmonary emboli
- Adverse effects
- Bleeding
- Hypotension
- Fever
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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)
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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.
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