Pulmonary Embolism

LITERATURE

  • Pathophysiology: V/Q mismatch, but also, platelet-derived inflammatory mediators open up fenestrations in capillary endothelium leading to global hypoxia
  • Definitions (terms of massive vs submassive are outdated and misleading in that degree of clot burden does not correlate with outcome)
    • HIGH RISK:  Shock, End-Organ Hypoperfusion, Hypotension or Cardiac Arrest
    • INTERMEDIATE-RISK:  Signs of Right Heart Strain on Imaging, Elevated Troponin or BNP (or both)
    • LOW-RISK:  All others
  • Diagnosis:
    • Most common symptoms: dyspnea, pleuritic chest pain, tachypnea, tachycardia
      • Normal O2 sat does NOT mean no PE
      • Degree of hypoxemia does NOT correlate with size of PE
    • Most common ABG finding: acute respiratory alkalosis
    • D-dimer has a low specificity in the ICU setting (if negative in ED however, ED physician can move on from that diagnosis)
    • If hemodynamically unstable:  Bedside echo, LE venous Dopplers, consider treating empirically
    • If hemodynamically stable obtain CTPE protocol (note that Cr should not dictate use of contrast, if it does can consider V/Q scan with LE dopplers)
    • Prognosis: evaluate for right heart dysfunction or injury
      • EKG, troponin, BNP, Echo, CT (can show dilated RV)
  • Treatment:
    • CODING PATIENT:
      • Either TNK or tPA 50mg bolus with other ACLS measures
    • Hemodynamically unstable
      • LYSE! 100mg tPA (20mg bolus, 80mg over 2 hours).  MOPETT trial suggests 50mg (20mg bolus with 30mg over 2 hours).  TNK on the horizon.  
      • Resuscitate: respiratory support as needed, cautious fluids bc of right-sided heart failure, vasopressors
      • Anti-coagulate after tPA: heparin (prevents further propagation of clot, and also has anti-inflammatory properties – does not dissolve clot)
    • Hemodynamically stable
      • Anti-coagulate
      • Heparin may be preferred for several reasons: if considering procedure, concerned for bleeding (quick off-set), decreased bioavailability of enoxaparin d/t subcutaneous fat, kidney dysfunction
      • Otherwise can use enoxaparin 1 mg/kg BID
      • If planning on OP therapy, can simply start DOAC
      • Consider lysis if there are signs of right-heart strain by BNP, troponin, and Echo (you do not need all 3) – consider half-dose of 50mg tPA
      • Reasons to consider IVC filter:
        • Contraindication to anticoagulation
        • Recurrent PE despite adequate anticoagulation
    • Beware “Emboli in Transit” – if there are findings of thrombus in the heart get IR and CT Surgery involved
    • ACCP Consensus conference on antithrombotic therapy: 3 months for provoked PE (surgery, immobilization, estrogen, trauma); 3-6 months for unprovoked; indefinite for non-modifiable risk factor (such as active cancer)
    • CDT and Surgical Interventions are utilized when anticoagulation and lysis are not options

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