Venous Thromboembolism Flashcards
What is a venous thromboembolism (VTE)?
- a blood clot forms most often in the deep veins of the leg, groin or arm
- referred to as deep vein thrombosis (DVT)
- it can travels in the circulation, lodging in the lungs, known as a pulmonary embolism (PE).
Where are deep vein thrombosis most common?
- deep veins and only unilaterally
- most common in the legs
What is Virchows triad?
- a triad of risk factors for developing venous thrombosis
What are the 3 risk factors in Virchows triad?
- circulatory stasis (blood stoping or slowing)
- hypercoagulable state (increased risk of coagulation)
- vascular injury
In normal blood flow it is always moving, but if they blood slows or even stops, this is referred to as circulatory stasis. What are some common risk factors for circulatory stasis?
- pregnancy
- long haul flights
- lower limb surgery
- bed rest
Vascular injury is a part of Virchows triad, what are some common risk factors for this?
- surgary
- previous DVT
- sepsis (blood infection)
- cannula, pacemakers
What are some of the most common factors that can induce a hypercoaguable state?
- smoking - MOST COMMON
- oestrogen (oral contraceptives)
- menopause treatment
- active cancer
- inherited and acquired thrombophilias
What is acquired thrombophilia in relation to deep vein thrombosis (DVT)?
- disease that increases the risk of DVT (blood clots)
What is the most common acquired thrombophilia?
- antiphospholipid syndrome
- immune system attacks phospholipids
Antiphospholipid syndrome is the most common acquired thrombophilia, what is it?
- immune disorder
- body produces antibodies attacking phospholipids
Antiphospholipid syndrome is the most common acquired thrombophilia, who is most affected?
- women
- 70% females affected
- increases the risk of pregnancy complications
Dysfibrinogenaemia is the second most common acquired thrombophilia, what is it?
- dysfunction in fibrin is created
- fibrinogen is more likely to form fibrin
- levels of fibrin appear normal
- most common in liver disease as fibrinogen made here
What is the most common cause of inherited thrombophilia, which causes increased risk of blood clot formation?
- Factor V Leiden
- factor V (5) of coagulation is affected
Factor V Leiden is the most common cause of inherited thrombophilia, what is it?
- mutation in factor V (5)
- protein C is anti-coagulating acting on factor V (5)
- in this disease that doesnt happen so coagulation continues
Factor V Leiden is the most common cause of inherited thrombophilia, is it dangerous?
- not generally
- only 10% of people with disease need treatment
Prothrombin thrombophiliais the second most common cause of inherited thrombophilia, what is it?
- mutation of factor II (2) which is prothrombin
-
What happens in inherited thrombophilias when there is protein S and C deficiency?
- these are anti-coagulants
- without these coagulation would increase
When investigating a DVT we can perform a d-dimer test. What is this?
- d-dimers are a product of fibrin
- only present when coagulation system has been activated
- if levels are high, suggests thrombosis is breaking down
- can be good to rule out DVT
What is the Wells Score used in DVT?
- probablily score for the risk of developing a DVT
- if score is low then low probabily of DVT
- if low wells score and negative d-dimer patient has low risk of DVT
If a patient has had a d-dimer test and a Wells Score calculated and you are still unsure if the patient has a DVT, what imaging technology can you use?
- ultrasound
- ultrasound doppler (blood flow)
- ultrasound compressability (thrombotic veins cannot compress)
If a patient has had a d-dimer test, wells score and ultrasound and the clinician is still unsure, what test can be performed?
- contrast venography
- dye inserted into veins
If a patient has a positive d-dimer test, is this diagnositc?
- no
- high sensitivity = correctly identify if patient has DVT
- low specificity = correctly identify if patient does not have DVT
What is the difference between sensitivity and specificity?
- Sensitivity = ability to correctly identify patients with a disease
- Specificity = ability to correctly identify people without the disease
Are patients with a DVT always treated?
- no
- depends on symptoms and location
- calf generally clears itself
If a patient has a DVT in the iliac or femoral veins, what treatment would they be prescribed?
- used to be warfarin
- now direct oral anticoagulants (DOAC) are used
- DOAC = RivaroXAban and Dabigatran
If a patient with a DVT has been prescribed with direct oral anticoagulants (DOAC) such as RivaroXAban and Dabigatran, how long are they given for in a first and second DVT?
- first = 3-6 months
- second = lifelong
What is a pulmonary embolis?
- emboli = something moving from one area of body to another in blood
- blood clot that has landed in the lungs
What are the most common symptomns of a pulmonary embolism?
- breathlessness (lack of blood flow so hypoxia)
- pleuritic chest pain
- haemoptysis
- hypoxia
- tachycardia
What is the investigation of choice for a deep vein thrombosis and pulmonary embolism?
- DVT = doppler ultrasound
- PE = CT pulmonary angiogram
When deciding how to investigate a patient with a suscpected pulmonary embolism, what is the order of investigation?
- Wells score - needs high risk of DVT
- d-dimer test - must be positive
- CT pulmonary angiogram (CTPA) - only after Wells and d-dimer tests
Previously to CT pulmonary angiograms, ventilation perfusion lung scans were performed, what is this?
- isotypes are inhaled and detected on imaging modality
What is the treatment of choice for a pulmonary embolism?
- heparin is the 1st treatment as acts quickly
- low molecular weight heparin called Enoxaparin
Once a patient is stable, heparin can be stopped and then they are switched to different medication. What are the most common medications used?
- warfarin or direct oral anticoagulants (DOAC)
- DOAC = RivaroXAban and Dabigatran
When a patient is prescribed warfarin or direct oral anticoagulants (DOAC), such as RivaroXAban and Dabigatran for a pulmonary embolism, how long are they prescibred these for?
- first PE = 3-6 months
- second PE = lifelong
If a patient has a suscpected pulmonary embolismn, why can giving the patient intravenous fluids help cardiac output?
- ⬆️ fluids = ⬆️ venous return
- ⬆️ venous return = ⬆️ cardiac output due to sterlings law
If a patient has a suspected massive pulmonary embolism what can they be given following fluids?
- thrombolytic drugs
- break down clots
If a pulmonary embolism needs to be operated on, what are the two most common treatments?
- embolectomy (opens up the chest)
- catheter fragmentation (breaks down clot)
What is the mortality risk for patients with a pulmonary embolism who recieve no treatment or even if they do recieve treatment?
- 30% without treatment
- 5% with treatment
What is the annual mortality from venous thrombolism worldwide?
- 220 million
- 15,000 deaths in UK/year
What is number 1 cause of preventable hospital deaths in the UK?
- venous thromboembolism (VTE)
- likley to be causes by all 3 aspects of Virchow’s triad
- 50% of VTE patients die 90 days after hospitalisation
To try and reduce the risk of Venous Thromboembolism, what are hospitals trying to do?
- perform a risk score
- low dose of heparin following surgery
- venous compression socks
- mobilisation
- hydration
