Pulmonary Embolism

• What are the different types of embolism?

  Mycotic

  Fat

  Air

  Thrombotic
• What is a mycotic embolism?

  Transfer of infective pathogens to the lungs from a distant source
• What are the common causes of mycotic emboli?

  IV injections (iatrogenic or drug use)
• What is shown in this image?

  Lung abscess

  
• What are fat emboli?

  Fat emboli are small particles of fat that enter the bloodstream and can block blood vessels, leading to tissue damage and organ dysfunction.
• What do fat emboli often occur?

  After long bone fractures -> multifocal inflammation in lungs
• What are air emboli?

  Air emboli are bubbles of air that enter the bloodstream and can cause blockages in blood vessels
• What is Virchow's triad?

  Venous stasis

  Endothelial disruption

  Hypercoagulability
• PE is the 2nd cause of adult sudden death.
• D-dimer is only used in negative prediction.

  Positive D-dimer does not mean it is a DVT/PE.
• What are the investigations for PE?

  D-dimer

  Doppler USS

  V/Q Scan

  Echocardiography

  CT pulmonary angiogram
• What is V/Q matching?

  Air that reaches lung is matched by the amount of blood flow in the capillaries in lungs
• What is dead space?

  An area of lung with ventilation but inadequate perfusion - O2 cannot enter bloodstream
• What is shunt (in relation to V/Q matching)?

  When there is adequate blood flow or perfusion, but not enough ventilation
• What would an echocardigram show in PE?

  Poor sensitivity & specificity for PE

  May show Right ventricular strain
• CTPA is highly sensitive & specific for acute PE.
• What is shown in this image?

  Saddle PE (in CT pulmonary angiogram)

  
• What are the major risk factors for PE?

  DVT

  Previous DVT or PE

  Active cancer

  Recent surgery

  Lower limb trauma

  Significant immobility

  Pregnancy

  Other factors…

  • COC/HRT
  • Long-distance travel
  • Obesity
  • Age > 60
• What is the treatment of PE?

  Anticoagulation (usually DOACs)
• How long are patients with PE anti-coagulated for?

  Pts with a strong, transient, provoking risk factor -> 3 months treatment

  Pts with ongoing strong risk factor OR unprovoked events -> extended treatment (usually for life, will be discussed with pt)
• How are PESI scores used?

  Pulmonary Embolism Severity Index

  Assess 30 day mortality

  Low risk pts will be managed as an outpatient
• What patients can you not inject/cannulate unnecessarily due to air emboli?

  HHT

  Osler-Weber-Rendu
• Why is the lung less sensitive to air emboli in pulmonary circulation?

  Oxygenated supply from bronchial arteries

  Alveoli are full of air -> simple diffusion will supply cells (to a degree)

  -> abundant collateral circulation

  Extensive collateral circulation & efficiency of gas transfer = minimal impact when there is a small air emboli

  Lungs are able to absorb small air emboli
• How does a PE lead to death?

  Lung tissue is ventilated but not perfused -> intra-pulmonary dead space & impaired gas exchange

  Thrombus reduces cross-sectional area of pulmonary arterial bed -> elevated pulmonary arterial pressure -> right ventricle has to work harder to force blood through the lungs -> reduced CO -> potential circulatory collapse & cardiac arrest due to right ventricular failure -> alveolar collapse -> worsens hypoxaemia
• What is involved in the PESI score?

  Age

  Sex

  Comorbid conditions (HF, cancer)

  HR

  BP

  Resp rate

  Temp

  Mental status

  O2 sats
• What is given to pts with haemodynamic instability & PE?

  Thrombolytics & heparin
• What is the difference between massive & submassive PE?

  Massive - systemic hypotension or shock

  Submassive - haemodynamically stable with right ventricular strain
• Fill in the blanks

  A) High risk PE

  B) Low or intermediate PE

  C) Systemic thrombolysis

  D) Low risk PE

  E) Intermediate low

  F) Intermediate high

  
• What is CTEPH?

  Chronic thromboembolic pulmonary hypertension
• What happens in CTEPH?

  incomplete resolution of pulmonary emboli