Class 20 review Flashcards
aPTT purpose and normal value
Activated partial thromboplastin time
Assessment of intrinsic coagulation by measuring factors I, II, V, VIII, IX, X, XI, XII
Measured in seconds how long to clot
25-35 sec
D-dimer purpose and normal value
Measures fragment of fibrin that is formed due to fibrin degradation/ clot lysis. Tells you that the clotting process is occurring in the body
<250 mcg/L
INR purpose and normal value
International normalized ratio
Standardized way of reporting PT - compares PT with a control value
0.8-1.2
PT purpose and normal value
Prothrombin time
Assessment of extrinsic coagulation by measurement of factors I, II, V, VII, X
11-16 sec
Platelet count purpose and normal value
Count of number of circulating platelets
(150 x 10^9)/L to (400 x 10^9)/L
What is VTE?
vein inflammation with a resulting thrombus
Important factors for the etiology of VTE
Venous stasis
Endothelial damage
Hypercoagulability of the blood
Venous stasis
Dysfunctional vein valves
Inactive extremity muscles
Change in unidirectional blood flow
Endothelial damage
Release of clotting factors
Activation of platelets
Blood hypercoagulability
Imbalance in clotting mechanism → coagulation
Increase in fibrin production
Clinical manifestations of VTE
Unilateral leg edema Pain Tenderness with palpitation Dilated superficial veins Sense of fullness in legs Paresthesias (tingling) Warm skin but body temp <38 degrees C
Symptoms of thrombocytopenia
Bleeding (mucosal or cutaneous) Petechiae Ecchymoses (discolouration of skin from bleeding underneath) Prolonged bleeding Hemorrhage
Immune Thrombo-Cytopenic Purpura (ITP)
Acquired/Immune
Platelets are mistakenly coated with antibodies when they reach the spleen they are destroyed by macrophages within 1-3 days
Thrombotic Thrombo-Cytopenic Purpura (TTP)
Acquired/Non-Immune
Typically has an underlying cause (e.g. infection). There is an enhanced agglutination of platelets which form microthrombi that deposit in arterioles and capillaries. It is a medical emergency.
Heparin Induced Thrombo-Cytopenia with Thrombosis (HIT or HITT)
Acquired Nonimmune
Thrombocytopenia develops 5-10min after heparin therapy is started
Venous thrombosis and arterial thrombosis can develop
Body begins to attack platelets as a result of drug therapy
Acquired Thrombocytopenic from Decreased Platelet Production
Acquired Nonimmune
The body does not produce as many platelets because there is an external factor inhibiting production. It can be from a disease or causative agent (e.g. drug). This is common in chemotherapy for cancer treatment.
Platelet level 150 X 10^9/L
This is considered thrombocytopenia
Platelet level 50 X 10^9/L
Prolonged bleeding will occur with trauma or injury
Platelet level 10 X 10^9/L
Spontaneous life-threatening bleeding
Thrombus definition
formed clot in the vascular system
Emboli definition
a blockage that has moved from one part of the vascular system to another
Phlebitis definition
inflammation (redness, tenderness, warmth, mild edema) of a superficial vein without the presence of a thrombus – very common with IV therapy
Superficial Vein thrombosis definition
thrombus in a vein near the skin surface – generally benign
Deep Vein thrombosis (DVT) definition
thrombus in a deep vein, most commonly the iliac and femoral veins of the leg – varies in severity – reduces blood return from the limb, increases vessel distention/edema distal to the blockage, thrombo-emboli may break away and travel to the lung causing a Pulmonary Embolism (PE – potentially life threatening). May be a long clot with a tail.
Superficial Vein Thrombosis clinical manifestations
- Usually superficial leg veins- sometimes in the arms
- Tenderness, rubour, warmth, pain, inflammation and induration along the vein
- Vein appears as a palpable cord
- Edema rarely occurs
- If left untreated, DVT can occur
Deep Vein Thrombosis clinical manifestations
- Deep veins of the arms, legs, pelvis and pulmonary systems
- Tenderness or pressure over involved vein, induration of overlying muscle, venous distension, edema, mild to moderate pain, deep rubour, increased temperature
- Pulmonary HTN, post-thrombotic syndrome may occur
Risk factors for venous thrombo-embolism
Venous stasis Hypercoagulability of blood Dehydration or malnutrition Erythropoiesis-stimulating drugs (eg epoetin alfa [Eprex]) Oral contraceptives Polycythemia vera Endothelial damage
Life Threatening Complication of VTE: Pulmonary Embolism
- Blockage of pulmonary artery by air, fat, tumor tissue or a thrombus
- Lodges in blood vessel obstructs perfusion of alveoli
- 30% mortality in untreated clients
- Diagnosis plus anticoagulant therapy mortality rate is 6-8%
Anticoagulant drugs
For arterial and venous thrombosis
Heparin (enoxaparin)
Warfarin (for long term)
Antiplatelet drugs
For arterial disease
Aspirin
Clopidogrel
How Thrombolytics Work
• Thrombolytic medications are mostly used during acute stroke or acute myocardial infarction
• They are used to destroy the clot and restore perfusion in the brain and heart
Are expensive, dangerous, high risk
Heparin MOA
Activates antithrombin, which then inactivates thrombin and factor Xa
Route, onset, duration, monitoring for heparin
Route: IV or subQ
Onset: Rapid (minutes)
Duration: Brief (hours)
Monitoring: aPTT or anti-Xa heparin assay
Warfarin MOA
Inhibits synthesis of vitamin K-dependent clotting factors, including prothrombin and factor X
Route, onset, duration, monitoring for warfarin
Route: PO
Onset: Slow (hours)
Duration: Prolonged (days)
Monitoring: PT (INR)
Reversal agent of heparin
protamine
Reversal agent of warfarin
vitamin K
Antifibrinolytic agents (e.g. aminocaproic acid)
- IV/PO administration
- Inhibit fibrin breakdown by inhibiting the formation of plasmin from plasminogen
- Helps to keep bleeding episodes under control (nose, mouth, throat and post-dental extractions)
- Most useful for preventing recurrent bleeding/less helpful in stopping an ongoing bleed
Which of the following laboratory information should the nurse monitor to detectheparin-inducedthrombo-cytopenia (HIT) in a client who is receiving a continuous heparin infusion? • Prothrombin Time (PT) • Red blood cell count • International Normalized Ratio (INR) • Activated prothrombin time (aPTT)
Activated prothrombin time (aPTT)
A client with avenousthrombo-embolism (VTE) is started on enoxaparin and warfarin. The client asks the nurse why two medications are necessary. Which of the following responses by the nurse is accurate?
• “Administration of two anticoagulants reduces the risk for recurrent venous thrombosis.”
• “Enoxaparin will start to dissolve the clot, and warfarin will prevent any more clots from occurring.”
• “The enoxaparin will work immediately, but the warfarin takes several days to have an effect on coagulation.”
• “Because of the potential for a pulmonary embolism, it is important for you to have more than one anticoagulant.”
“The enoxaparin will work immediately, but the warfarin takes several days to have an effect on coagulation.”
