Pulmonary Embolus

Question 1

How common is it?

Answer 1

1 in 1000 in the UK have a DVT each year – if untreated, 1 in 10 DVTs go on to develop into PEs. Half of all people with a PE develop it when they are a hospital inpatient. 25,000 deaths per year in England are due to blood clots (PEs that have happened after a DVT) that have developed whilst a person was in hospital.

Question 2

Who does it affect?

Answer 2

-People more prone to thromboembolism (see risk factors).

Question 3

What causes it?

Answer 3

• Usually arise from a venous thrombosis in the pelvis or legs. Clots break off and pass through the veins and the right heart before lodging in the pulmonary circulation.
• Rare causes – right ventricular thrombus (post- MI), septic emboli (right sided endocarditis), fat, air or amniotic fluid embolism, neo-plastic cells, parasites.

Question 4

What risk factors are there (and how can they be reduced)?

Answer 4

• Recent surgery – especially abdominal/pelvic or hip/knee replacement.
• Thrombophilia
• Leg fracture
• Prolonged bed rest/reduced mobility
• Malignancy
• Pregnancy/postpartum; OCP/HRT
• Previous PE

Question 5

How does it present?

Answer 5

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 eg. DVT.

Question 6

How would you investigate the patient?

Answer 6

• FBC, U&E, baseline clotting, D-dimers
• ABG may show ↓PaO2 and ↓PaCO2
• Imaging – CXR may be normal, or show oligaemia or affected segment, dilated pulmonary artery, linear atelectasis, small pleural effusion, wedge shaped opacities or cavitation (rare).
• ECG may be normal or show: tachycardia, right bundle branch block, right ventricular strain (inverted T in V1 to V4). Classical SI QIII TIII pattern is rare.

Question 7

What treatment/s would you consider? What risks and benefits of treatment are there?

Answer 7

• Anticoagulate with LMW heparin.
• Start warfarin.
• Stop heparin when INR is >2 and continue warfarin for a minimum of 3 months.
• Thrombolysis for massive PE (alteplase)
• Consider placement of veno caval filter inn patients who develop emboli despite adequate coagulation.