Pulmonary Embolism

Podcast: Play in new window | Download

Introduction

Pulmonary embolism (PE) is caused when a deep venous thrombosis from somewhere else in the body “embolizes” and becomes lodged in the pulmonary arteries

Can cause pulmonary infarction (which mimics pneumonia on chest x-ray)

Basic Approach to the Diagnosis of PE

• Step 1: Consider PE in any patient with signs or symptoms consistent with the disease
  • Common signs/symptoms
    • Shortness of breath
    • Chest pain
    • Syncope
    • Tachycardia
    • Hypoxemia
    • Hypotension
• Step 2: Do not do additional testing for PE in patients with a CLEAR alternative diagnosis
  • Common alternative diagnoses
    • COPD exacerbation
    • Acute coronary syndrome
    • Pneumonia
  • Keep in mind that these diagnoses are also the most frequent misdiagnoses in cases of missed PE!!! Be careful.
• Step 3: Calculate Wells Score and PERC criteria
  • Wells score
    • (I personally use Wells’ Criteria for PE by MDCalc)
    • Define patient as either “Low” “Medium” or “High” risk
  • PERC criteria
    • I use the PERC Rule for PE by MDCalc for this as well
  • If patient is both low risk wells and meets all PERC criteria…
    • No additional testing needed!!!
• Step 4: Get a D-Dimer
  • IF…
  • Low risk Wells but fails PERC criteria
  • Medium risk Wells score
• Step 5: Get a CTA
  • IF…
  • Wells score is high
  • Elevated d-dimer
    • (Update: it is now established that you can safely use AGE ADJUSTED D-DIMER)
      • ACEP’s clinical policy supporting this can be found HERE

Final Thoughts

• Bilateral lower extremity ultrasounds not sensitive enough to rule out PE
• The classic EKG finding is S1Q3T3

Additional Reading

• Emergency Evaluation of PE: Diagnosis (Journal of Emergency Medicine)
• Wells Criteria (MDCalc)
• PERC Criteria (MDCalc)
• Age Adjusted D-Dimer Policy (ACEP)