PE - pulmonary embolism

Question 1

what is a PE

Answer 1

A thrombus (clot) that has embolised (travelled) and lodged in the pulmonary circulation

Question 2

what causes a PE

Answer 2

• PE is usually (95%) the result of a DVT - Virchow’s triad
• DVT breaks off and travels to pulmonary artery or one of its branches.
• Atrial fibrillation can cause PE
• blood clots form in the atria due to stasis, and then embolize to the pulmonary arteries
• trauma (road accidents)

Question 3

Pathophysiology

Answer 3

• Perfusion is limited
• V/Q mismatch - oxygen in alveoli but not enough RBCs
• So, decreased O2 sat in blood (hypoxemia)
• Pulmonary vasoconstriction
• Results in respriatory alkalosis as increased ventilation leads to hyperventilation so CO2 lost

Question 4

Large PE

Answer 4

cardiovascular shock, low BP, central cyanosis, sudden death

Question 5

Medium PE

Answer 5

pleuritic pain, haemoptysis, breathless

Question 6

small PE

Answer 6

Small recurrent- progressive dyspnoea, pulmonary hypertension and right heart failure

Question 7

symptoms

Answer 7

• Dyspnoea - acute onset (difficult breathing)
• Pleuritic chest pain (sharp chest pain when breathing deeply)
• Haemoptysis (coughing up blood from lungs or bronchial tubes)
• Symptoms of DVT - leg pain, swelling etc.
• Collapse (/sudden death)
• Fever

Question 8

signs

Answer 8

• Tachycardia
• Hypoxia
• Cyanosis
• Low BP
• Hyperventilation

Question 9

complications

Answer 9

PE with atrial septal defect may cuase embolic stroke

Question 10

what is the main investigation

Answer 10

CT Pulmonary Angiogram (CTPA) - MAIN TEST

• If Wells score indicates a PE is likely - perform a CTPA
• If Wells score indicates a PE is unlikely - perform D-dimer and if positive perform a CTPA

Question 11

• V/Q scan used insread of CTPA in patients with:

Answer 11

• renal impairment
• contrast dye allergy
• pregnancy
• at risk from radiation where a CTPA is unsuitable
• Avoid using CTPA for pregnant women (use USS or V/Q), however if patient is very unwell CTPA is the best modality so accept risk of radiation

Question 12

what is the wells score Used to determine

Answer 12

an individual’s likelihood of having a PE

Question 13

other imaging

Answer 13

• CXR - will be normal early in PE (before infarction), used to rule out other causes, ‘wedge-shaped infarct’ indicates PE
• USS leg - if radiation to be avoided or DVT suspected

Question 14

other tests

Answer 14

• ECG - sinus tachycardia, S1Q3T3 (right heart strain pattern)
• Troponin - may be raised due to strain on right ventricle, raised troponin is associated with worse outcomes
• ABG - type I resp failure, respiratory alkalosis
• Investigate underlying cause - USS, cancer screen, autoantibodies (SLE), thrombophilia screen

Question 15

PESI - Pulmonary Embolism Severity Index

Answer 15

Low risk: low PESI; -ve troponin; no oxygen; no co-morbidities
- Ambulatory pathway → Home

Question 16

First line drugs in pulmonary drugs that cause circulatory failure

Answer 16

Thrombolytic drugs

Question 17

surgical management

Answer 17

• Pulmonary thombectomy - surgical removal of pulmonary embolism
• Prevention of secondary PE (filter over the vena cava)

Question 18

Acute management

Answer 18

Anticoagulation
- apixaban or rivaroxaban (DOACs) first line

• May be outpatient if patient considered low-risk
• If neither apixaban or rivaroxaban are suitable then either LMWH followed by dabigatran or edoxaban OR LMWH followed by a vitamin K antagonist (VKA, i.e. warfarin)

Question 19

Secondary prevention (long-term)

Answer 19

• Inhibit clotting cascade, prevent clot formation (dont breakdown clots)
• Long term anticoagulation - warfarin, a DOAC or LMWH
• Treatment with a should be continued for at least 3 months