Pulmonary Embolism (PE)

Question 1

What is a Pulmonary Embolism?

Answer 1

when an embolus gets trapped in the pulmonary arteries and blocks blood flow to the lung tissue. This puts a strain on the right side of the heart. This can lead to severe cardiorespiratory failure.
* embolus= a blood clot (thrombus), air bubble, fatty deposit, or other material.
* embolism= when an embolus has been carried in bloodstream to block a vessel, at a location different to where it was formed.

Question 2

PE: Aetiology

Answer 2

• Caused by any form of embolism
• PEs are usually caused by a thromboembolism.
• venous thromboembolism (VTE) is when a PE is caused by a DVT.

Question 3

PE: Risk Factors

Answer 3

Risk factors of PEs are mainly associated with the factors that contribute to thrombus formation. The risk factors for thrombus formation PE can be categorised according to Virchow’s triad:
Stasis
* Immobility - Prolonged bed rest, hospitalization, Immobilizer or cast, long-distance travel, or sedentary lifestyle/occupation.
* Malignancy - Solid tumors
* Pregnancy and postpartum period: (Hormonal changes and) venous stasis
Endothelial Injury
* Surgery - Particularly lower limb orthopedic procedures.
* Trauma - Direct injury to blood vessels or immobilization post-injury.
* Chemotherapy
* Central venous catheterization
Hypercoagulability
* Pregnancy and postpartum period - hormonal changes (and venous stasis)
* Hormone therapy particularly with oestrogen - Oral contraceptives, hormone replacement therapy, or selective estrogen receptor modulators. When the liver metabolises oestrogen in tablet form, it releases clotting factors
* Genetic predispositions - Factor V Leiden, prothrombin gene mutation, deficiencies in protein C, protein S, or antithrombin.
* Hypercoagubility disorders - Polycythaemia (raised haemoglobin), Thrombophilia, Systemic lupus erythematosus
* Malignancy - some cancers release more clotting factors than others
* Increasing age (>60 years old)
Medical Comorbidities
* Heart failure, inflammatory bowel disease, nephrotic syndrome, or obesity/hypercholesterolemia

ask about risk factors such as immobility, surgery and long-haul flights

Question 4

PE: Symptoms

Answer 4

Presenting symptoms can range from asymptomatic (discovered incidentally) to sudden death. Presenting features include:
* Dysponea + tachyponea
* Pleuritic chest pain - due to pulmonary infarction
* Cough + Haemoptysis
* Features of DVT (including unilateral leg pain, tenderness and swelling and/or erythema of a leg or an arm)
* syncope/dizziness/stroke - in older patients and severe PE
* Chronic thromboembolic pulmonary hypertension
* Cardiac complications: right heart failure, cardiac arest
* Low-grade fever (pyrexia) - caused by underlying condition/systemic symtpom

Question 5

PE: Cardiovascular Examination

Answer 5

• Typicalclinical findingsin PE:
  
  • tachyponea - Raised respiratory rate
  • Tachycardia
  • Hypotension secondary haemodynamic instability
  • poor perfusion of the extremities
  • pleural rub, hypotension
  • Hypoxia
  • venous distention (elevated jugular venous pressure)
  • gallop rhythm
  • shock

Question 6

PE: Investigations

Answer 6

• Bedside investigations:
  
  • Pulse oximetry
  • Pulmonary embolism rule-out criteria (PERC) - for a low pre-test probability of PE (<15%), but want more reassurance that PE isn’t the diagnosis. Allthe criteria must be absent for a negative PERC. If positive PERC, complete further investigations
  • 2-level PE Wells score - for a high pre-test probability of PE (>15%). The clinical probabilty decides the next step.