Respiratory System >
Pulmonary Embolism (PE)
“A blockage of the artery of the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism)”
Risk Factors
- Modifiable:
- Prolonged bed rest / reduced mobility
- Non-Modifiable:
- Recent surgery
- Thrombophilia
- Leg fracture
- Malignancy
- Pregnancy/postpartum
- Previous PE
Aetiology & Pathophysiology
- Venous thrombosis → clots break off and pass through veins to the right side of the heart → lodge in the pulmonary circulation
- Rare causes:
- Right ventricular thrombus (post-MI)
- Septic emboli (right-sided endocarditis)
- Fat
- Air
- Amniotic fluid embolism
- Neo-plastic cells
- Parasites.
Clinical Presentation
Small emboli may be asymptomatic, whereas large emboli are often fatal.
- Symptoms:
- Acute breathlessness
- Pleuritic chest pain
- Haemoptysis
- Dizziness
- Syncope
- Ask about risk factors, past history or family history of thromboembolism
- Signs:
- Pyrexia
- Cyanosis
- Tachypnoea
- Tachycardia
- Hypotension
- Raised JVP
- Pleural rub
- Pleural effusion
- Look for signs of a cause, e.g. deep vein thrombosis.
Investigations
- Bloods:
- FBC, U&E, baseline clotting, D-dimers
- ABG – may show Low PaO2 and Low PaCO2
- Imaging:
- Chest X-Ray – may be normal, or show:
- Oligaemia of the affected segment
- Dilated pulmonary artery
- Linear atelectasis
- Small pleural effusion
- Wedge-shaped opacities
- Cavitation (rare)
- Chest CT pulmonary angiogram
- Chest X-Ray – may be normal, or show:
- Special:
- ECG – may be normal, or show:
- Tachycardia
- Right bundle branch block
- Right ventricular strain (inverted T in V1 to V4)
- The classical SI QIII TIII pattern is rare
- ECG – may be normal, or show:
Management
- Haemodynamically stable patient:
- LMW Heparin OR Unfractionated Heparin if underlying renal impairment
- Treat for 5 days
- Then start DOAC or Warfarin
- For Warfarin, stop Heparin when INR is 2-3 due to initial prothrombotic effect of Warfarin
- Consider Vena Caval Filter if a contraindication to anticoagulation
- Haemodynamically unstable patient:
- Thrombolysis for massive PE – Alteplase
Prevention
- Give Heparin to all immobile patients
- Stop HRT + COCP pre-op