Junior Doctor Notes 🩺

Pulmonary Embolism

4 min read

Presentation

  • See: Dyspnoea
  • A small PE causes sudden dyspnoea, pleuritic pain and possibly haemoptysis, with few physical signs. Look for a low-grade pyrexia (>38°C), tachypnoea (>20/min), tachycardia and a pleural rub
  • A major PE causes dyspnoea, chest pain and light-headedness or collapse, followed by recovery. Look for cyanosis, tachycardia, hypotension, a parasternal heave, raised JVP and a loud delayed pulmonary second sound

Investigations

Bedside

Bloods

  • Consider performing an ABG
    • Do not routinely unless pulse oximetry is reliable or demonstrates unexplained hypoxia on room air
    • Low Pa, Low , High pH
    • Characteristic findings include acute respiratory alkalosis, or hypoxia and a raised A-a gradient
  • D-dimer
    • Age adjusted cutoff 0.01 x age if >50 y/o

ECG

  • Significant PE may cause right axis deviation and right BBB but most common sign is sinus tachycardia (S1Q3T3 is neither specific nor sensitive for PE)

Imaging

  • Calculate the clinical pre-test probability of PE before requesting any diagnostic imaging
  • Can use D-dimer to exclude PE in low probability pre-test patients
  • Can use ELISA D-dimer to exclude PE in moderate probability pre-test patients

NOTE

Only send a D-dimer test in

  • Patients ≥50 years with a low pre-test probability or
  • In any patient <50 with a low pre-test probability but who fails to fulfil one or more PERC criteria
    • If all PERC criteria are fulfilled, the patients does not have a PE and does not need a D-dimer test sent

  • PERC needs to be 0 to rule out PE
  • If PERC positive → YEARS score + D-dimer
  • Arrange a CTPA or V/Q scan in:
    • All patients with a high or intermediate pre-test probability
    • Those with a positive D-dimer

CTPA

  • CTPA has >95% sensitivity for segmental or larger PEs and ~75% for subsegmental
  • More useful if the CXR is abnormal (V/Q scan is difficult to interpret)
  • Arrange sequential V/Q scan ±lower limb Doppler u/s or CT venogram if doubt remains

V/Q Scan

  • V/Q scan preferred over CTPA if:
    • Patient is allergic to contrast dye
    • Patient has renal failure
    • When the CXR is normal
    • Younger females
  • A normal V/Q scan rules out clinically important PE in patients with low-to-moderate pre-test probability

Chest-Xray

  • Frequently normal; mainly to exclude other diagnoses such as pneumonia or pneumothorax
  • Plate or linear atelactasis
  • Unilateral pleural based wedge shaped pulmonary infiltrate
  • Unilateral pleural effusion
  • Raised hemidiaphragm
  • Dilated pulmonary artery in massive PE
  • Areas of oligaemia in massive PE

Management

  • Give high-dose oxygen via mask, aiming for oxygen saturation >95%
  • Give IV normal saline to support BP if necessary
    • Avoid excessive fluid ∵ worsens RV dilation → septal shift → worsens LV function
  • Vasopressors: Norad first line, dobutamine
  • Relieve pain with titrated morphine 2.5 mg IV boluses
  • Can use PESI score or simplified PESI score to determine risk of 30 day mortality

Anticoagulation

  • Commence anticoagulation when:
    • The diagnosis is confirmed or
    • When there is an intermediate or high pre-test probability of PE but a delay to testing (in the absence of contraindications)
  • 2 anticoagulation options exist:
    • Start heparin and warfarin and continue heparin until warfarinisation achieved (3-5 days)
    • NOAC
  • Duration
    • Provoked: minimum 3 months
    • Unprovoked: >3 months
    • Cancer associated: >6 months
      • Can use DOAC or clexane
        • LMWH for GI/GI cancers and high bleeding risk
      • DOAC can be used for lung, breast, prostate, haem (unless thrombocytopenia), ovarian, brain

Heparin + Warfarin

  • Give LMWH such as enoxaparin 1mg/kg SC BD
    • LMWH does not require aPTT monitoring
  • In patients with haemodynamic compromise, give UFH (80 U/kg IV bolus) followed by maintenance infusion of 18 U/kg/h titrated to aPTT (1.5-2.5x control value)
  • If patient already on warfarin and has a PE consult cardiothoracics for consideration of transvenous vena caval filter
  • Commence first dose of warfarin 5mg PO on the first day of heparin therapy and titrate ssubsequent daily doses to achieve an INR of 2.5-3.5

NOAC/DOAC

  • NOAC such as rivaroxaban 15mg PO 12 hourly or apixabanm 10mg PO 12-hourly
  • Check renal function
  • Cannot use in child-pugh class B or worse without specialist input

Dabigatran

Dabigatran requires at least 5 days of parenteral anticoagulant to be given first. Dose is 150mg PO 12-hourly. Dose modification is required based of renal function

Fibrinolytic Therapy

  • Consider when the probability of PE is high (or confirmed) and:
    • The patient is hypotensive despite fluid resuscitation and/or
    • Has evidence of acute RV failure and/or
    • Is peri-arrest
  • Call immediate senior help and MET Activation Criteria
  • Give tPA 10mg IV over 1-2 minutes then 90 mg IV over 2 hours together with heparinisation
    • Can consider streptokinase and urokinase
  • Stat fibrinolytic doses can be given in cases of cardiac arrest considered related to a massive PE

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