Pulmonary Embolism Flashcards
What is an embolism?
Movement of material from one part of the circulation to another
What sorts of things can embolise?
Blood, air, tumours, amniotic fluid, fat
What are the risk factors for thromboembolism?
Surgery, obesity, cancer, immobilisation, HF, the pill, pregnancy, HRT, long haul travel
What are some of the symptoms of PE?
Dyspnoea, pleuritic chest pain, cough, syncope
What are some physical signs seen in PE?
Pleural rub (in cases of pulmonary infarction) Rasied JVP
What are the main differential diagnoses of PE?
MI, pneumothorax, pneumonia/pleurisy
What is the commonest finding on a chest x-ray of a patient with a PE?
A normal CXR - done to exclude other diagnoses
What may be shown on an ECG of a patient with a PE?
Right ventricular strain - T wave inversion in right precordial leads (V1-V4, II, III, aVF)
SI QIII TIII
(Deep S wave in lead I, Q wave in lead III, T wave inversion in lead III)
What may a patient’s blood gases show in PE?
May show hypoxaemia and hypocapnia (resp alkalosis) due to hyperventilation
What is D dimer?
A fibrin degradation product released into the blood when a thrombus is degraded by fibrinolysis (not normally present in the blood except when the coagulation system has been activated)
What is included in Wells’ score for predicting clinical likelihood of PE?
1) Clinical signs and symptoms of DCT
2) No alternative diagnosis more likely than PE
3) Heart rate > 100
4) Immobilisation at least 3 days or surgery in previous month
5) Previous DVT or PE
6) Haemoptysis
7) Malignancy
How is PE treated?
Oxygen and immediate heparinisation
How does heparinisation reduce mortality?
Stops thrombus propagation in pulmonary arteries and allows the body’s fibrinolytic system to lyse the thrombus
What happens after initial heparinisation of a patient with a PE?
Patient started on oral anticoagulant (eg warfarin)
What are the clinical consequences of pulmonary embolism?
1) Affected areas are ventilated but not perfused - air in affected alveoli do not participate in gas exchange so become alveolar dead space. Blood is redirected to unaffected areas - but if this extra blood
flow is not matched by increased ventilation the paO2 drops, although sufficient carbon dioxide is usually removed to prevent hypercapnia. (V/Q MISMATCH)
2) A rise in pulmonary artery pressure due to obstruction of the vessel, causing right heart strain/failure, reducing cardiac output
3) Poorly perfused part of the lung may undergo infarction (less likely due to bronchial arteries supply)
