Venous Thrombosis - DVT and PE Flashcards
What is venous thromboembolism?
Thromboembolic event occurring within the venous system
-DVT
-PE
1 in 1000 people have this a year, what is it?
DVT
What causes venous thromboembolism’s?
-Stagnation of blood flow (immobilisation)
-Hypercoagulability (inherited)
-Vascular injury (trauma/surgery)
-Endothelial injury
How does endothelial injury cause venous thrombosis?
-Collagen exposure
-Platelet aggregation
-Thrombus
What risk factors put a patient at risk of venous thrombosis ?
Age, Obesity, Varicose veins, Long haul flights, Immobility, Pregnancy and puerperium, Previous VTE, Male Sex
What predisposing conditions put a patient at more of a chance of having venous thrombosis?
-Trauma or surgery
-Malignancy
-CCF, recent AMI
-Infection
-Hormone therapy
-Inherited acquired disorders
-Vasculitis
What score is used to diagnose venous thrombosis?
Wells clinical score
*Higher or equal to 3, High probability
* 1 or 2 moderate probability
*Less than 0, low probability
What does the Wells Clinical score, clinical parameters?
-Active cancer
-Paralysis or recent plaster immobilisation
-Bedridden for more then 3 days/major surgery on past 4 weeks
-Entire leg swelling
-Localised tenderness along distribution of deep venous system
-Calf swelling of more than 3cm compared to asymptomatic leg
-Pitting oedema
-Previous DVT
-Collateral superficial veins
How can levels of D-dimer assay diagnose a venous thrombosis?
1) Thrombus formation
2) Fibrinolytic response
3) Plasmin generation
4) Fibrin breakdown
5) Release of fibrin degradation products (predominately D-dimer)
Who commonly will have a false positive of the D-dimer assay?
Elderly
What can affect the D-dimer assay?
Position of the clot, and heparin use
What imagining is used first to diagnose venous thrombosis?
Duplex ultrasonography (Dopler)
-Non-invasive
-High sensitivity
If a patient appears to have symptoms of venous thrombosis, but it isn’t that what else could it be?
-Physical trauma
-Cellulitis
-Ruptured Baker’s cyst
-Oedema
How are Venous Thrombosis managed?
-Identify and treat any underlying cause
-Prevent damage to valves of veins
-Allow normal circulation to limbs
-Prevent PE
-Immediate management with injectable anticoagulant
What is the first choice anticoagulant for a venous thrombosis?
Heparin
How does unfractionated heparin (UFH) work?
On the intrinsic pathway
-Binds to antithrombin III,
-Inhibits factor Xa (10a)
-thrombin
What are the side effects of unfractionated heparin?
Haemorrhage, Thrombocytopenia, Hyperkalaemia, Osteoporosis, Alopecia
What should be monitored when the concern could be thrombocytopenia?
Monitor platelets if the patient is on UFH for more than 5 days!
What is the normal activated partial thromboplastin time (APTT)?
30-40 seconds
What is the APTT ratio?
Pts APTT at a given time / APTT reference value
What are some examples of low molecule weight heparin? (LMWH)
Enoxaparin, Tinzaparin
What type of heparin has less effect on Thrombin?
LMWH
What heparin has more effect on factor Xa?
LMWH
What heparin has a decreased risk of thrombocytopenia and osteoporosis?
LMWH
What oral anti-coagulation is used after LMWH?
Coumarins
-Warfarin
-Acenocoumarol
-Phenindione
DOACS
How long is oral anti-coagulation after a venous thrombosis event given?
Usually 3 months (can be longer)
How does Warfarin work?
Inhibits metabolism of vitamin K and affects the activation of factors II, VII, IX, X
What is the onset of action for warfarin?
8-12 hours, full effect not seen for 48-72 hours
What needs monitoring when a patient is on warfarin?
Baseline: Clotting screen, Hb, Plts, LFTs
INR and signs of bleeding
What is the normal INR ratio?
1-1.2
What does Dabigatran Etexilate work on?
Direct thrombin inhibitor
DOAC
What does Rivaroxaban, Apixaban, Edoxaban work on?
DOAC
Direct inhibitor of activated factor X
What do compression stockings do?
*Assist calf muscle pump
*Decrease venous hypertension
*Decrease venous valvular reflux
*Decrease leg oedema
*Aids microcirculation
*Prevention of venous ischemia
Why do pulmonary embolisms occur?
Blood clot or thrombus formed in the venous systems, normally clot originates in the calf
-These break free and embolise to lung
-There are normally multiple clots
What happens when a pulmonary embolism obstructs the pulmonary artery system?
*Increase pulmonary artery pressure
*Right heart failure
*Infarction of lung tissue
What are the symptoms of a PE?
*Acute onset chest pain
*General malaise
*Dyspnoea
*Haemoptysis
*Cough
*Wheeze
*RR above 16
*Abdo pain
*Anxiety
*Cardiac arrhythmias
*Syncope
How are PE’s diagnosed?
*Chest X-ray
*V/Q Scan
*Lab tests
-PaO2 decreased
-WCC, ESR, D-dimer levels increased
*ECG
-Could be tachy!!
If a patient doesn’t have a PE what other diagnosis could they have?
ACS, Pneumonia, CCF, AF, Acute Anaemia, COPD/Asthma!
What do they give immediately when someone has a PE?
*Immediate anticoagulation in DVT
What Fibrinolytics are given for PE?
-Urokinase
-Steptokinase
-Alteplase
-Reteplase
How do Fibrinolytic drugs work?
-Activate plasminogen, breakdown of formed fibrin
-Only used for really big PE’s
