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Pulmonary Embolism (PE)

This is where a embolus is sent the origin site of a thrombus, which then lodges itself in a pulmonary artery. Risk factors of it include:

  • Immobility, Recent surgery, Long-haul flights - Very important to ask about this!

  • Pregnancy

  • COCP/HRT

  • Cancer, thrombophilia, polycythaemia, lupus, previous hx

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“Pulmonary embolism” © Laboratoires Servier (Licensed under CC-BY 3.0) https://creativecommons.org/licenses/by/3.0/


Main presenting symptoms here are:

  • Sudden-onset SOB

  • Pleuritic chest pain

  • Haemoptysis


Other clinical features here include:

  • May be signs of DVT (unilateral swollen, tender calf)

  • Tachycardia

  • Hypoxia

  • Hypotension, cyanosis

  • Signs of Right Heart strain if large PE (e.g. raised JVP, parasternal heave, and loud P2)


N.B. In a clinical setting, it tends to present very subtly with either sinus tachycardia or even a new oxygen requirement.


Wells Score

This score is used to stratify the risk in patients with suspected PE.

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Investigations

If Wells score is 4 or less:

  • D-dimer

    • Low excludes PE, Raised calls for further imaging diagnostic i.e. CTPA


If Wells score is 4 or more:

  • CTPA

    • Patient is usually given LMWH in the interim if clinical suspicion is high or there’s a delay with imaging

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“A large pulmonary embolism at the bifurcation of the pulmonary artery (saddle embolism)” © James Heilman (Licensed under CC-BY 3.0) https://creativecommons.org/licenses/by/3.0/


A VQ scan can be done if CTPA isn't availble. It would show a raised ratio as there's a drop in perfusion with preserved ventilation. Instances in which a VQ scan is preferable is:

  • Pregnancy

  • Severe renal impairment

  • Contrast allergy


Other investigations to do include:

  • Bloods - FBC, U&E, CRP, INR, ABG, D-dimer

  • ECG - Tachycardia, Right heart strain (P pulmonale, RAD, RBBB, non-specific ST/T wave changes)

  • CXR - rule out differentials e.g. pneumonia, pneumothorax


Management

If the patient is haemodynamically unstable

  1. Start Unfractioned Heparin (UFH) first - Load on 10,000 units IV, followed by an infusion at a rate of 18 units/kg/hour

  2. Thrombolysis (with IV Alteplase)

  3. Switch to DOAC/LMWH after thrombolysis


N.B. UFH is very useful short-term agent as it has a very short-half life and works within minutes. This makes it’s use predictable, and easily reversible e.g. with protamine.


If the patient is haemodynamically stable, give a DOAC e.g. apixaban, rivaroxaban. This is given for 3 months if a provoked PE, or 6 months if an unprovoked PE. If patient is having recurrent PE's, they should be prescribed a DOAC for life. Alternative is a LMWH.


Prophylaxis - LMWH, Compression stockings (contraindicated in peripheral arterial disease).


N.B. Other options include an IVC Filter if the patient is having recurrent PE’s despite being on anticoagulation or if they're unable to be given anticoagulants e.g. allergy.




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