L19: Venous Thromboembolism Flashcards
What are the 2 pathways in the coagulation cascade
Intrinsic pathway
Extrinsic pathway
What factor does both extrinsic and intrinsic pathway actvate
Factor 10
What does activated factor 10 acitvate
Pro thrombin to thrombin
What does thrombin do
Cleave fibrinogen to fibrin
What does fibrin do
With factor 10 it creates the clot
What does the virchows triad describe
3 factors that cause a clot
What is the virchows triad compose of
Hypercoagulabiltiy
Stasis
Vascullar wall injury
What can stasis (blood flow slowing down) be caused by
Atrial fibrillation Left ventricular dyfunction Bed bound immbolity Venous insufficiency Venous obstruction
If a thrombus forms in the veis where can it embolise to
Lungs
If a thrombus form in the arterial system where can it embolise
Periphery (rest of the body)
What is clots that embolise from deep veins to the lungs called
pulmonary embolism
What are sings of deep venous thrombosis
Pain Swelling Erythema Tenderness Wartmth Pitting oedema
What is a WELLS score dvt for
A score that estimates whether dvt is likely or unlikely
What blood test can we do to look for dvt
D-dimer
What does a positive d dimer mean
There is a clot somewhere but not necessarily due to a dvt
What does a negative d dimer mean
There is no thrombosis i.e we can exclude dvt and pe
What are the other methods to diagnose dvt
Ultrasound
Venography: invasive injecting a needle to the foot
What is a pulmonary embolis
A block of a lung vessel by an embolism
What is a complication of pe
Right ventricular Hypertrophy as the right ventricle is pumping harder
What are the symptoms of pe
Minor: sudden onset of chest pain, shortness of breath, haemoptysis
Massive pe: right heart strain, haemodynamically unstable
What are the signs of a pe
Sob Pleuritic chest pain Cough Tachynpoe Tachycardia Crepitations after a pe Cyansosi Collapse
What is the wells pe score
A two level pe score that sees if pe is likely or unlikely. A score more than 5 is likely
On an ecg what signs are you likely to see in a pulmonary embolism
Sinus tachycardia Right axis deviation Right bundle branch block T investion in v1,2,3 Or S1,q3,t3 (deep s waves in 1, q waves in 3 and t inversion in 3)
What can a chest-xray show in pe
Can be normal
Big pulmonary infarct- wedge shaped infarct
Atelactasis
Small pleural effusion
Cxr are useful in excluding alternatives
What blood test can you do to look for pe
D-dimer
Abg
What sensitive and specific test can be carried out for diagnosing pe
Ct pa (ct pulmonary angiogram)
If patient is presenting with acute chest pain what can be done to investigate
Ctca (ct coronary angiogram) to exclude coronary artery disease, aortic dissection and pulmonary embolism
What other scan can we carry out to look at the perfusion of the lungs
Isotope lung scan - normal perfusion will exclude pe
How can we prevent pe
Hydration Early mobilisaton VTE prophylaxis Elastic compression stocking Inferioir vena cava filters- a mesh that stops the clot from going from leg to the heart
How do we prevent further clot formation
Heparin (anticoagulant)
Enoxaparin
Warfarin (long term anticoagulant)
Non vitamins oral anticoagulants
To relieve circulatory obstruction what do we do for someone with a massive pe
Thrombolysis (drugs that are infused with iv to dissolve the thrombus and aid blood flow)- used in emergency
If the wells score is more than 4 for pe what needs to be done
A ctpa
If the wells score is less than 4 what needs to be done
a d-dimer blood test
Whilst you wait for a d dimer blood test what needs to be offerred to the patinet
Apixaban
If the d dimer is raised what needs to be done
A ctpa to rule out pe
If a pe is confirmed what is the treatment
Anticoagualtion therapy for 3 months e.g low molecular weight heparin (enoxaprin)
