Pulmonary Embolism

PULMONARY EMBOLISM

  • Pathophysiology: V/Q mismatch, but also, platelet-derived inflammatory mediators open up fenestrations in capillary endothelium leading to global hypoxia
  • Definitions:
    • Submassive PE = signs of RV strain without hypotension or cardiogenic shock
    • Massive PE = RV dysfunction with arterial hypotension or cardiogenic shock
  • 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 hemodynamically unstableàBedside echo, LE venous Dopplers, consider treating empirically
    • If hemodynamically stable and kidney function allowsàCT-PE
    • If hemodynamically stable and CXR normal and/or Cr precludes contrast CTà V/Q scan
    • Prognosis: evaluate for right heart dysfunction or injury
      • EKG, troponin, NT-pro-BNP (Tulane)/BNP (UMC), Echo, CT (can show dilated RV)
    • Risk scores to help with disposition and treatment decisions:
      • PESI (Pulmonary Embolism Severity Index) predicts 30-day outcome of patients with PE
        • Note: patients with renal failure/severe comorbidities were excluded from the validation study
      • POMPE-C Score predicts 30-day mortality for patients with active cancer and PE
        • Better for cancer patients than PESI
      • RIETE Score stratifies risk of major bleeding with anticoagulation for DVT/PE
        • Not yet externally validated
      • Treatment:
        • Hemodynamically unstableà
          • LYSE! 100mg tPA over 2 hours
          • 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 stableà Anti-coagulate
          • Start anticoagulation within 24 hours
          • 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
          • Consider lysis if there are signs of right-heart strain by BNP, troponin, and Echo (you do not need all 3)
        • Enoxaparin preferred over warfarin for cancer-related PE
        • Reasons to consider IVC filter:
          • Contraindication to anticoagulation
          • Recurrent PE despite adequate anticoagulation
        • 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)