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Pulmonary Embolus (PE)

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Definition of pulmonary embolus/embolism (PE)

  • Embolus (usually from a thrombus in the deep veins of the leg or pelvis) which lodges in the pulmonary arteries

 

Epidemiology of pulmonary embolism (PE)

  • 1 per 1000 people per year
  • Commoner in older people
  • 20% higher in black people, 30% lower in Asian
  • 25% unprovoked, 50% temporary risk factors, 25% have underlying malignancy

 

Risk factors for pulmonary embolus (PE)

  • Previous VTE
  • Patient
    • Age > 60
    • Obesity
  • Situation
    • Immobility
    • Prolonged travel
  • Condition
    • Acute medical illness
    • Surgery – especially lower limb orthopaedic surgery
    • Malignancy
    • Thrombophilia
    • Pregnancy
    • OCP/HRT

 

Presentations of pulmonary embolism (PE)

  • Non-massive PE
    • Pain (pleuritic)
    • SOB
    • Tachypnoeic – 85%
    • Fever – 40%
    • Tachycardia – 30%
    • Localised pleural rub and/or coarse crackles
    • Haemoptysis (may be delayed up to 3 or more days)

 

  • Massive PE
    • Central chest pain
    • Collapse
    • Haemodynamic compromise
    • AF
    • Raised JVP with prominent a-wave (contraction of distended atria)
    • Failure: RV heave, gallop rhythm, widely split second heart sound

 

Differential diagnosis of pulmonary embolism (PE)

  • Acute coronary syndromes (ACS)
  • Pneumothorax
  • Pneumonia
  • Aortic dissection
  • Cardiac tamponade

 

[youtube height=”HEIGHT” width=”WIDTH”]https://www.youtube.com/watch?t=534&v=yMJ9sjxu6KU[/youtube]

 

Well’s score in pulmonary embolism (PE)

  • Use Well’s score to asses probability of PE (see below)
  • Low or Medium probability: do a D-Dimer. If negative, look for another cause of symptoms.
  • High probability: do a CTPA or VQ scan

 

Factor Points
Clinically suspected DVT 3
Alternative diagnosis less likely than PE 3
Tachycardia 1.5
Immobilisation/surgery in previous four weeks 1.5
History of DVT or PE 1.5
Haemoptysis 1
Malignancy (treatment in preceding 6 months or palliative stage) 1

 

Interpretation of the Well’s score in pulmonary embolism (PE)

  • 0-4 = PE unlikely
  • > 4 = PE likely

 

Investigation of pulmonary embolism (PE)

  • ABG
  • Bloods
    • Including D-dimer (depending on Well’s score) clotting and troponin
  • CXR
    • May show wedge infarction
    • Atelectasis (due to collapse of non-perfused alveoli, which then don’t make surfactant)
    • Pleural effusion
    • Rule out consolidation
  • ECG
    • Right ventricular strain
      • ST depression and T-wave inversion in right-sided chest leads, V1-V3 (also limb leads I, II and AvF potentially)
    • Classic S1 Q3 T3 pattern, which is rare.
  • CTPA (CT pulmonary angiography)
    • Positive predictive value 96% with high Wells score
    • 92% with moderate Wells score
    • 58% with low Wells (BMJ 2013).
    • Also varies with size of PE (PPV 97% with main or lobular, 68% with segmental, 25% with subsegmental)
  • V/Q can be done if poor renal function, young age or pregnant
    • Needs a normal CXR beforehand
    • Can rule out PE if normal
  • USS to look for pelvis/femoral vein clots
  • Echoardiography
    • May show dilated RV or clot in RV outflow tract
  • MRA can also be done if CT contraindicated (e.g. due to contrast)
  • Further investigations if PE
    • If over 40 years old: PSA in men, mammography in women to look for underlying malignancy (as well as full history to looking for underlying malignancy)
    • Consider CT CAP and colonoscopy if any suspicion

 

Staging of pulmonary embolus (PE)

  • Massive: Embolus in the RV outflow tract
  • Non-Massive: Embolus in a terminal vessel

 

Initial management of pulmonary embolism (PE)

  • ABCDE
    • Oxygen
    • IV access
    • Bloods
    • ECG and CXR
  • Analgesia
  • Thrombolysis if haemodynamic compromise
    • Usually alteplase
      • Dosage in (peri)/arrest situation is different to that in hypotension – see local guidelines
  • Anticoagulation
    • Fondaparineux (10a inhibitor) or treatment dose heparin (UFH or LMWH) depending on local guidelines

 

Further management of pulmonary embolism (PE)

  • Oral anticoagulation
    •  Warfarin or Rivaroxaban
    • Continue LMWH if malignancy or pregnant
  • IVC Filter
    • Consider in patients who cannot have anti-coagulation treatment or who develop new PEs despite conventional treatment
    • Not a long term solution.
  • Embolectomy

 

Complications of pulmonary embolism (PE)

  • Post-thrombotic syndrome
  • Recurrence
  • Chronic thromboembolic pulmonary hypertension
  • Right heart failure

 

Prognosis of pulmonary embolism (PE)

  • 30% overall mortality but very dependent on severity

 

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Common Pulmonary Embolus (PE) exam questions for medical students, finals, OSCEs and MRCP PACES

 

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