Pulmonary Embolism Flashcards
How does thrombosis differ from haemostasis?
thrombosis occurs within the vessel while physiological haemostasis occurs outside the vessel wall as a result of injury
What are the the factors that influence thrombosis according to Virchow’s triad?
1) changes in blood flow (stasis or turbulence)
2) vessel wall dysfunction
3) changes in blood components, leading to hypercoagulability
Are venous thrombi red or white?
Red - rich in red blood cells and fibrin
Are arterial clots red or white?
White - rich in platelets
What is the most common cause of PE?
DVT
Other than a DVT, give 3 other sites where thrombi can originate to cause a PE:
1) upper limb
2) cerebral venous sinuses
3) splanchnic veins (hepatic, portal and mesenteric)
Give 12 risk factors for venous thromboembolisms:
1) surgery
2) coagulation disorders
3) immobilisation (bed rest >3 days)
4) age
5) trauma
6) recent long haul travel
7) acute medical admission
8) obesity
9) pregnancy
10) ethnicity
11) combined oral contraceptive/ HRT
12) cancer
Give 7 clinical presentations associated with pulmonary embolism:
1) pleuritic chest pain
2) breathlessness
3) haemoptysis
4) tachypnoea
5) tachycardia
6) crackles and pleural rub on auscultation
7) syncope
What is the nature of the chest pain experienced in a PE?
pleuritic
What auscultation findings support diagnosis of a PE? (2)
- Crackles
- Pleural rub
Give two examination findings that support diagnosis of a pulmonary embolism:
- Raised JVP
- Right ventricular heave (seen in severe cases)
What is the gold standard investigate for PE?
CT pulmonary angiogram
Describe ECG findings that would support a diagnosis of PE:
right ventricular strain pattern: T wave inversion in the inferior and right precordal leads
Give 4 initial investigations that may be used to assess breathlessness associated with a PE:
1) ECG
2) CXR
3) ABG
4) Biomarkers of cardiac injury such as BNP and troponin
What is the name of the risk calculator scoring system for PE?
Well’s Score
A score over how many points makes a PE ‘likely’ according to the Wells score?
> 4
Summarise the Wells Score criteria for pulmonary embolism risk:
1) signs and symptoms of DVT - 3 points
2) alternative diagnosis less likely than PE - 3 points
3) HR > 100 bpm - 1.5 points
4) immobilisation (>3 days) or surgery - 1.5 points
5) previous DVT/PE - 1.5 points
6) haemoptysis - 1 point
7) malignancy - 1 point
What investigation is used for patients deemed to be “PE unlikely” according to the Wells score?
D-dimer
Give 5 instances other than VTE where D-dimer may be raised:
1) advanced age
2) infection
3) inflammation
4) cancer
5) pregnancy
True or false: if Wells score verdict is “PE unlikely” but D-dimer is raised, you should still ensure the patient has a CT scan
true
Give an alternative to CTPA for investigation of PEs:
ventilation-perfusion isotope lung scanning
Describe the two phases of ventilation-perfusion isotope lung scanning:
1) perfusion phase - radio-labelled albumin is injected IV and used to access blood flow to the lung
2) ventilation phase - patients inhale radio labelled xenon to access air delivery to the lungs
Fill in the gap: diagnostic testing for suspected PE should be performed urgently and completed within __ hrs of the initial presentation
24
What is the initial treatment for PEs?
parenteral anticoagulants (Oral liquid)
Give two examples of anticoagulants that can be given parenterally:
1) LMWH
2) fondapurinux
Name the four types of DOAC:
1) apixaban
2) edoxaban
3) rivaroxaban
4) dabigitran
What does dabigitran inhibit?
thrombin
What clotting factor does apixaban, edoxaban and rivaroxaban inhibit?
Factor Xa
Which two DOACs are given AFTER (5 days) parenteral anticoagulants following a PE?
1) endoxaban
2) dabigitran
Which two can be used as an alterative to parenteral anticoagulation from the onset of a PE?
1) apixaban
2) rivaroxaban
What two anticoagulants should not be used in pregnant women?
1) warfarin
2) DOACs
(they can cross the placenta)
True or false: warfarin and LMWH are safe for breast feeding women
true
What anticoagulant should be avoided in breast feeding women?
DOACs
What anticoagulant is most effective in treating thrombosis in cancer patients?
LMWH (more so than warfarin)
True or false: thrombolysis therapy is not used in the treatment of PE or DVT unless the VTE is massive and likely to kill the patient
true
Give two surgical interventions for the management of PEs:
1) surgical embolectomy
2) inferior vena cava filters
How long should anticoagulation last after a PE at minimum?
3 months (then patient should be reviewed to decide on further anticoagulation)
What is post-thrombotic syndrome?
a complication of acute deep vein thrombosis, characterized by chronic pain, swelling and skin changes in the affected limb following the thrombotic episode
How can the risk of post-thrombotic syndrome be reduced?
Compression stockings
What is factor V leiden?
a mutation in clotting factor V that causes factor Va to be resistant to inactivation by activating protein C, leading to increased thrombin generation
Name 4 thrombophilia disorders?
- Factor V leiden
- Reduced antithrombin
- Reduced protein C and protein S
- Antiphospholipid syndrome
Describe how reduced/ dysfunctional antithrombin can increase thrombin risk:
antithrombin functions as an anticoagulant by inhibiting thrombin and factor Xa and without it, thrombin generation is increased
Describe how reduced/ dysfunctional protein C and protein S can increase thrombin risk:
protein C and protein S inhibit the clotting system and without them, thrombin generation increases
What vitamin are protein C and protein S dependent on?
vitamin K
What is antiphospholipid syndrome?
condition associated with autoantibodies directed against protein-binding phospholipids that results in increased coagulation activity
(may be the underlying cause of recurrent VTE episodes and VTE in younger patients)
