[8] Pulmonary Embolism Flashcards
What is a pulmonary embolism?
A sudden blockage of a major artery in the lung, usually by a blood clot
How serious is a pulmonary embolism?
Depends - the clot can be small and just damage the lung, or can be large and stop blood flow, in which case it can be fatal
Where do the emboli come from in pulmonary embolism?
90% come from proximal leg DVTs, or pelvic vein thrombosis
How do DVTs cause PEs?
They dislodge and migrate to the lung circulation
What causes the development of DVT?
Classically due to a group of causes, named Virchow’s triad
What is Virchow’s triad?
- Alterations to blood flow
- Factors in the vessel
- Factors in the blood
Other than DVT, what are the causes of pulmonary embolism?
- RV thrombus
- Septic thrombi from right sided endocarditis
- Fat, air, neoplastic, or amniotic fluid embolism
What are the risk factors for PEs?
- Recent surgery, especially abdominal/pelvic, or hip/knee replacement
- Thrombophilia
- Leg fracture
- Prolonged bed rest/reduced mobility
- Malignancy
- Pregnancy/postpartum
- HRT or combined contraceptive pill
- Previous PE
What are the symptoms of PE?
- Acute breathlessness
- Pleuritic chest pain
- Haemoptysis
- Dizziness
- Syncope
How are PEs investigated?
- History and examination
- Blood tests
- Chest x-ray
- ECG
What are the examination features of PEs?
- Pyrexia
- Cyanosis
- Tachypnoea
- Tachycardia
- Hypotension
- Raised JVP
- Pleural rub
- Look for signs of a cause, e.g. DVT
What blood tests are done in PE?
- FBC
- U&E
- Baseline clotting
- D-dimers
What is a D-dimer?
A protein fragment produced when a blood clot dissolves in the body
What levels of D-dimer are normal?
Normally it is undectable
When does D-dimer levels rise?
When the body is forming and breaking down clots, as in the case in PE
What does the CXR show in PE?
CXR may be normal, or may show;
- Oligaemia of affected segment
- Dilated pulmonary artery
- Linear atelactasis
- Small pleural effusion
- Wedge-shaped opacities
- Cavitation
What does the ECG show in pulmonary embolism?
May be normal, or may show;
- Tachycardia
- Right bundle branch block
- Right ventricular strain
What are the inital steps in the acute management of PE?
- Oxygen if hypoxic, 10-15L/min
- Morphine 5-10mg IV with anti-emetic if the patient is in pain or very distressed
- IV access and start LMWH/fondaparinux
- If decreased BP, give 500ml fluid bolus
What can be considered if a patient with PE is haemodynamically unstable?
Thrombolysis with alteplase
What dose of alteplase is given in PE thrombolysis?
10mg IV bolus, then IVI 90mg/2hours
What can be considered in a patient with PE who is haemodynamically stable but has persistent decreased BP?
Vasopressors, e.g. dobutamine 2.5-10mch/min IV or noradrenaline
What is required after immediate treatment of an acute PE?
Initiation of long-term anticoagulation
How long should long-term anticoagulation be given for after PE?
If obvious remedial cause, 3 months may be enough. Otherwise, continue for 3-6 months, long term if recurrent emboli or underlying malignancy
How can pulmonary embolisms be prevented?
- Give heparin to all immobile patients
- Stop HRT and the COCP pre-op, if reliable with other forms of contraception
