6. Pulmonary Embolism

Question 1

What are the 3 primary influences that predispose a patient to blood clot formation?

Answer 1

Endothelial injury
Stasis or turbulence of blood flow
Blood hypercoagulability

Question 2

What are the risk factors for thromboembolism?

Answer 2

Pregnancy
Prolonged immobilisation
Previous VTE
Contraceptive pill
Long haul travel
Cancer
Heart failure
Obesity
Surgery >30 mins
HRT
Age

Question 3

What are the hypercoagulable conditions?

Answer 3

Antithrombin III deficiency
Protein C or protein S deficiency or restart
- factor V Leiden mutation causing resistance to activated protein C
Lupus anticoagulant
Homocystinuria
Occult neoplasm
Connective tissue disorders

Question 4

What is the pathophysiology of clinical outcomes in PE?

Answer 4

Acute right ventricular overload/failure - leads to cardiogenic shock and/or cardiac arrest secondary to arrhythmias
Respiratory failure - due to areas of ventilation perfusion mismatch
Pulmonary infarction - areas of alveolar haemorrhage, results in haemoptysis, pleuritic and small pleural effusion

Question 5

What are the symptoms in PE?

Answer 5

Dyspnoea
Pleuritic chest pain
Cough
Substernal chest pain
Haemoptysis
Syncope 
Leg pain
Fever

Question 6

What are the signs of PE?

Answer 6

Tachypnoea
Rales or decreased breath sounds
Accentuated second heart sound
Tachycardia
Fever
Diaphoresis
Lower extremity oedema
Cardiac murmur
Cyanosis

Question 7

What are the differential diagnoses of the signs and symptoms of PE?

Answer 7

Pneumothorax
Pneumonia
MI
Pericarditis
Pleurisy
MSK chest pain

Question 8

What does an ABG show in PE?

Answer 8

May show hypoxaemia an hypocapnia due to hyperventilation

Sometimes PaO2 may be normal

Question 9

What does a CXR show in PE?

Answer 9

Often it is completely normal
May be done to rule out other diagnoses
May show wedge shaped pleural based infiltrate

Question 10

What does an ECG show in PE?

Answer 10

May show signs of right ventricular strain - T wave inversion in right precordial leads
Classic findings are deep S wave in lead I, Q wave in III, inverted T wave in III
Prone to supraventricular tachyarrhythmias

Question 11

What do D dimer investigations show in PE?

Answer 11

A normal D dimer effectively rules out PE in those at low likelihood of PE, not high
+ve D dimer, do further imaging

Question 12

What is the treatment of PE?

Answer 12

Give O2

Immediate heparinisation

Question 13

How does heparinisation reduce mortality?

Answer 13

1. Stop thrombus propagation in pulmonary arteries and allows body’s fibrinolytic system to lyse the thrombosis
2. Stops thrombus propagation at embolism source and reduces frequency of further PE
3. Does not dissolve clot

Question 14

What do you need to watch out for after heparinisation?

Answer 14

Heparin-induced thrombocytopenia

• body produces antibodies to a portion of heparin
• low platelet count

Question 15

What is the treatment for heparin-induced thrombocytopenia?

Answer 15

Immediate cessation of all formulations of heparin

Need to use non-heparin based anti-coagulant

Question 16

What is the treatment of high risk PE patients?

Answer 16

Haemodynamic support
Respiratory support
Exogenous fibrinolytics 
Percuatneous catheter directed thrombectomy
Surgical pulmonary embolectomy

Question 17

What happens after initial heparinisation?

Answer 17

Patients stated on an oral anticoagulant e.g. warfarin or DOAC

Question 18

What do you do if you cannot use any form of anti-coagulation for PE?

Answer 18

Inferior vena cava filter

Question 19

Who would you use an inferior vena cava filter on?

Answer 19

Large haemorrhagic CVA
Large oesophageal bleed
Retroperitoneal bleed

Question 20

How do you prevent DVT/PE in inpatients?

Answer 20

DVT prophylaxis after surgery

DVT prophylaxis for patients with malignancy