[8] Pulmonary Embolism

Question 1

What is a pulmonary embolism?

Answer 1

A sudden blockage of a major artery in the lung, usually by a blood clot

Question 2

How serious is a pulmonary embolism?

Answer 2

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

Question 3

Where do the emboli come from in pulmonary embolism?

Answer 3

90% come from proximal leg DVTs, or pelvic vein thrombosis

Question 4

How do DVTs cause PEs?

Answer 4

They dislodge and migrate to the lung circulation

Question 5

What causes the development of DVT?

Answer 5

Classically due to a group of causes, named Virchow’s triad

Question 6

What is Virchow’s triad?

Answer 6

• Alterations to blood flow
• Factors in the vessel
• Factors in the blood

Question 7

Other than DVT, what are the causes of pulmonary embolism?

Answer 7

• RV thrombus
• Septic thrombi from right sided endocarditis
• Fat, air, neoplastic, or amniotic fluid embolism

Question 8

What are the risk factors for PEs?

Answer 8

• 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

Question 9

What are the symptoms of PE?

Answer 9

• Acute breathlessness
• Pleuritic chest pain
• Haemoptysis
• Dizziness
• Syncope

Question 10

How are PEs investigated?

Answer 10

• History and examination
• Blood tests
• Chest x-ray
• ECG

Question 11

What are the examination features of PEs?

Answer 11

• Pyrexia
• Cyanosis
• Tachypnoea
• Tachycardia
• Hypotension
• Raised JVP
• Pleural rub
• Look for signs of a cause, e.g. DVT

Question 12

What blood tests are done in PE?

Answer 12

• FBC
• U&E
• Baseline clotting
• D-dimers

Question 13

What is a D-dimer?

Answer 13

A protein fragment produced when a blood clot dissolves in the body

Question 14

What levels of D-dimer are normal?

Answer 14

Normally it is undectable

Question 15

When does D-dimer levels rise?

Answer 15

When the body is forming and breaking down clots, as in the case in PE

Question 16

What does the CXR show in PE?

Answer 16

CXR may be normal, or may show;

• Oligaemia of affected segment
• Dilated pulmonary artery
• Linear atelactasis
• Small pleural effusion
• Wedge-shaped opacities
• Cavitation

Question 17

What does the ECG show in pulmonary embolism?

Answer 17

May be normal, or may show;

• Tachycardia
• Right bundle branch block
• Right ventricular strain

Question 18

What are the inital steps in the acute management of PE?

Answer 18

1. Oxygen if hypoxic, 10-15L/min
2. Morphine 5-10mg IV with anti-emetic if the patient is in pain or very distressed
3. IV access and start LMWH/fondaparinux
4. If decreased BP, give 500ml fluid bolus

Question 19

What can be considered if a patient with PE is haemodynamically unstable?

Answer 19

Thrombolysis with alteplase

Question 20

What dose of alteplase is given in PE thrombolysis?

Answer 20

10mg IV bolus, then IVI 90mg/2hours

Question 21

What can be considered in a patient with PE who is haemodynamically stable but has persistent decreased BP?

Answer 21

Vasopressors, e.g. dobutamine 2.5-10mch/min IV or noradrenaline

Question 22

What is required after immediate treatment of an acute PE?

Answer 22

Initiation of long-term anticoagulation

Question 23

How long should long-term anticoagulation be given for after PE?

Answer 23

If obvious remedial cause, 3 months may be enough. Otherwise, continue for 3-6 months, long term if recurrent emboli or underlying malignancy

Question 24

How can pulmonary embolisms be prevented?

Answer 24

• Give heparin to all immobile patients
• Stop HRT and the COCP pre-op, if reliable with other forms of contraception