Coagulation Disorders Flashcards
Heparin Induced Thrombocytopenia
Caused by abnormal antibodies that activate platelets, causing clots to form and depleting platelet counts in blood
Consumes the platelets, to be rendered useless. Impaired ability to clot
Antidote for heparin:
protamine sulfate
warfarin side effects:
cholesterol microemboli
Anticoagulants
Anticoagulant: prevent to body from completing the clotting cascade and developing a blood clot. Prevents clot formation; does not break down existing clots. NOT A THROMBOLYTIC
Heparin and LMWH
- Heparin: enhances antithrombin III activity
o Decreases thrombin activity
o Decreases prothrombinase - LMWH
o Also enhances AT-III activity but more specific to prothrombinase (active factor X)
o Fever adverse effects than heparin
o Less risk of thrombocytopenia compared to heparin - Used for acute thromboembolic disorder including DVT, PE, unstable angina, and evolving MI
- Prophylaxis for clotting
- Monitor PTT when on heparin.
Warfarin, apixaban, rivaroxiban are all anticoagulants
Anti-platelets (ex. aspirin)
- antagonize the receptors that communicate with platelets, thereby preventing platelet aggregation, and preventing clot formation.
- inhibit platelet aggregation
Receptors used in platelet aggregation
ADP receptors
glycoprotein IIb/IIIa receptors
Thrombolytics
breakdown existing clots. Converts plasminogen to plasmin, which then degrades fibrin in clots.
Anti-fibrinolytics
refers to drugs that prevent the breakdown of fibrin/existing clots, thereby preventing excessive bleeding. does this by displacing plasminogen from fibrin, inhibiting fibrinolysis.
PT - prothrombin time
measures the time it takes plasma to clot when exposed to tissue factor, which assess the extrinsic and common pathways of coagulation.
aPTT: activated partial thromboplastin time
measures the time it takes plasma to clot when exposed to substances that activates the contact factors, which assesses the intrinsic and common pathways of coagulation
INR
international normalized ratio): the normal range for PT varies by laboratory and reagent/instrument combination, therefore the result is always reported along with a control factor, which is the INR. INR results will be similar on a blood sample tested in any library using any thromboplastin reagent/instrument system when calibrated correctly.
what conditions are antiplatelet agents prescribed for?
- Reduce risk of CVA/MI
- Reducing thrombolytic events post – CVA/MI
- Prevent DVT
- Prevent thrombi formation unstable angina/coronary stents
Foods that interfere with coagulation: counter effects of anticoagulant
o Foods high in vitamin K will counter the effects of the anticoagulant
o Alcohol is high in vitamin K, as well as cranberry juice
o Kale, spinach, Brussel sprouts, collards, mustard greens, chard, broccoli, asparagus
Foods that are natural anticoagulants
o Turmeric/ginger/garlic/cayenne pepper
• Know which nursing assessments need to be performed prior to the administration of a thrombolytic and WHY
- Need to give thrombolytics ASAP. Ideally in less than an hour. Can be given a max of 4.5 hours after CVA has occurred.
- Obtain complete health history including allergies and drug history
- Obtain baseline vital signs
- Obtain lab values for clotting times and CBC
• When would an anti-fibrinolytic be administered and what is important to assess for in the patient’s history prior to administration?
o Used to prevent and treat excessive bleeding post-op
o Usually given during or after surgery so the site will stop bleeding
o Heavy menstrual bleeding
o Displaces plasminogen from fibrin. Inhibits fibrinolysis
o Assess clotting time, CBC
Process of Hemostasis: Three major steps
- intrinsic and extrinsic pathways both lead to formation of prothrombinase
- prothrombinase coverts prothrombin to thrombin
- thrombin coverts fibrinogen to fibrin
- fibrin strands trap RBCs forming a clot.
Role of platelet in hemostasis
o Platelets adhere to and aggregate at site of injury in vessel
o Platelet activation leads to formation of fibrin network that trap RBCs forming clot
Role of Cofactors in hemostasis
o Ca2+ and vitamin K are critical for synthesis of clotting factors
Platelet disorders
- Due to decreased production resulting in low platelet counts (thrombocytopenia) – not able to clot as easily
o Bone marrow suppression
o Folic acid and B12 deficiency
o Decreased thrombopoietin (in liver failure) – platelets <100 - Hemophilia and von Willebrand’s disease
o Genetic conditions result in in absence of clotting factors difficulty clotting
Warfarin
- Reduced vit K (active vitamin K) is a cofactor for the production of clotting factors including thrombin and prothrombinase
- Warfarin inhibits two enzymes necessary for formation of reduced vitamin K.
- Monitor INR when on Warfarin
Thrombolytics: tPA
Plasmin – tissue-plasminogen activator (tPA) and urokinase-plasminogen activator convert plasminogen into active plasmin which breaks down fibrin.
