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Nursing 3 Test 3
Hemostasis
| Question | Answer |
|---|---|
| Hemostasis | the clotting process-control of bleeding and clotting |
| Stages of Hemostasis | Injury, Vascular Spasm, Platelet Plug formation, Formation of fibrin clot, clot dissolution or fibrinolysis |
| Platelet Plug | platelets are activated, combine with von Willebrand factor, adhesion & aggregation of platelets, formation of soft platelet plug |
| formation of stable blood clot | clotting factors activated in a chain reaction(cascade), soluble firbrinogen converted to insoluble fibrin, fibrin strands form a mesh, RBC's.platelet plug & other cells trapped |
| Clotting factors | inactive circulating plasma proteins, assigned names and Roman numerals, must be activated to initiate clotting, activated factor:Roman numeral and "a", |
| Intrinsic clotting cascade | XII(12) to XI(11) to IX(9) to VIII(8) then to common pathway |
| Extrinsic clotting cascade | VII(7) then to common pathway |
| common pathway clotting cascade | X(10) to II(2)-Prothrombin to thrombin to I(1)-Fibrinogen to Fibrin |
| Intrinsic | intravascular injury, triggering events: venous stasis, bacterial endotoxins, catheter insertion(foreign body), can be initiated by exposre to glass(blood in a glass bottle) |
| Extrinsic | extrinsic to blood vessels, damaged tissue cells release tissue factor, shorter faster pathway |
| common pathway | both pathways lead to activation of Factor X, Prothrombin(II) converts into Thrombin and Thrombin converts fibrinogen(I) into fibrin |
| Clot dissolution | (fibrinolysis), damaged tissues release t-PA(tissue plasminogen activator), t-PA causes lysis of the clot, end result of lysis: FDP's or FSP's (fibrin degradation/split products) |
| FDP | fibrin degradation |
| FSP | fibrin split products |
| Role of Liver in hemostasis | Liver synthesizes factor VII(12), Prothrombin(II), fibrinogen(I) and other factors |
| Role of Vit K | needed to make factors |
| Liver disease or low Vit K causes... | decreased prothrombin and increased bleeding |
| Coagulation Tests... | detect increased bleeding tendency, detect increased risk of thrombus formation, monitor effects of anticoagulant drugs |
| Types of Coagulation tests | platelet count, Prothrombin time(PT) & INR, aPTT, fibrin degradation products, D-Dimer |
| Normal platelet count | 150,000-300,000/uL |
| low platelet count | thrombocytopenia |
| elevated platelet count | thrombocytosis |
| risk of severe bleeding at this platelet count | <50,000 u/L |
| risk of spontaneous and fatal bleeding at this platelet count | <20,000 u/L |
| platelet transfusion given at this platelet count | <10,000 u/L |
| Prothrombin time(PT) | measures factors of the extrinsic pathway, measures effectiveness of coumadins |
| normal PT value | 12-15 secs |
| INR | expresses PT as a ratio |
| Target therapeutic range of INR varies... | 1-2(prevention of DVT), 2.5-3.5(aortic valve) |
| aPTT | tests the intrinsic pathway, if prolonged, test to determine which factor is defecient or defective, monitors heparin therapy |
| Normal aPTT is | 30-45 secs |
| therapeutic range of aPTT | 1.5-2.5 times mean value |
| Fibrin Degradation Products | (FDP's), present in DIC, monitors fibrinolytic therapy |
| D-Dimer | measures one of the fragments, present DIC, MI and DVT |
| anticoagulant indications | treatment and prophylaxis, DVT & PE, MI, atrial fibrillation, cardiovascular disease |
| Heparin | given when coumadin is contra-indicated, effectiveness monitored by PTT(aPTT) |
| Heparin is contraindicated in pt's with | hemophilia and thrombocytopenia |
| antidote for Heparin | protamine sulfate |
| LMWH | Low Molecular Weight Heparin |
| LMWH given | subQ |
| LMWH used for | DVT prophylaxis and when coumadin is contraindicated |
| Advantages of LMWH over Heparin | longer action:more predictable, may be self administered, does not require frequent testing |
| examples of LMWH | Enoxaparin(Lovenox) and Dalteparin(Fragmin) |
| Fondaparinux | Arixtra-factor Xa inhibitor, non-heparin anticoagulant, given SQ for DVT prophylaxis, contraindicated in renal dx, can cause thrombocytopenia, check CBC(platelet),and serum creatinine periodically |
| Warfarin | (coumadin)-given PO, Vit K antagonist, Onset of effects slow(takes 48-96hrs), No concurrent use of ASA,NSAID, interacts w/many drugs & herbals |
| antidote for warfarin(coumadin) | Vit K |
| contraindications for warfarin(coumadin) | teratogenic(absolutely contraindicated in pregnancy), avoid brest feeding(switch to heparin) |
| Aspirin | Inhibits platelet adhesion, 80mg is sufficient, effects lasts the life of the platelets(5-7 days), prophylactic use(reduction of risk for stroke & second MI) |
| Adverse effects of Aspirin | GI, heartburn, epigastric pain, ulcer, bleeding |
| Clopidogrel | (Plavix)-prevents platelet activation and aggregation, oral agent, reduces risk of thrombosis in stroke, MI, Less GI disturbances than Aspirin |
| anticoagulants: nursing intervention | understand concentration, drip rates, weigh pt(how doses are determined, esp heparin), monitor for signs of bleeding, have antidotes available |
| anticoagulants: patient teaching | avoid or limit foods high in Vit K(warfarin), limit alcohol, follow up care, meidic alert, notify if undergoing invasive tests,surgery, avoid IM, blood sticks, use existing IV's, older adults:fall risk |
Created by:
jbittner
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