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Chapter 206. Pulmonary Embolism

Arif M. Shaik, MD; Adel Bassily-Marcus, MD, FCCP, FCCM

  • Lower extremities DVT found in 70% of patients with PE
  • PE is life-threatening in critically ill patients with a 30% mortality rate

Clinical Assessment

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Modified Geneva Score
FactorPoints
Age ≥651
Surgery/fracture within 1 month2
Active malignancy2
Hemoptysis2
Previous DVT or PE3
Unilateral lower limb pain3
HR 75–943
HR ≥955
Pain on deep palpation of lower limb, unilateral edema4
Probability of PE:
  • 0–3 points: low probability (8%)
  • 4–10 points: intermediate probability (28%)
  • ≥11 points: high probability (74%)

  • High index of suspicion: Any patient with immobilization with above symptoms should be evaluated
  • Intraoperative or postoperative: long bone fracture repair with unexplained symptoms should be evaluated for fat emboli
  • Complicated vaginal or Cesarean delivery patients evaluated for amniotic fluid embolization

Diagnostic Tests

  • EKG: classic signs of right heart strain demonstrated by an S1–Q3–T3 pattern (Figure 206-1) are observed in only 20% of patients with proven PE
  • Arterial blood gas shows slight alkalosis and raised alveolar–arterial oxygen gradient
  • Increased cardiac markers (BNP, troponin T and I): suggest RV strain; perform echo; discuss thrombolysis

Figure 206-1. Classic EKG Pattern in PE
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S wave is apparent in lead I (blue arrowhead), Q wave in lead III (black arrowhead), and inverted T wave in lead III (blue arrow). Reproduced from Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas of Emergency Medicine. 3rd ed. Figure 23-47B. Available at: http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.

Imaging

  • Chest x-ray: usually normal in PE, occasional atelectasis, consolidation, and elevated hemidiaphragm with lung infarcts seen
  • CT angiography (CTA) is the initial imaging modality of choice for stable patients, sensitivity 96–100%, specificity 89–98%
  • Ventilation–perfusion (V/Q) scans should be used only when CT is not available or if the patient has a contraindication to intravenous contrast; only useful if normal chest x-ray. Preferable if pregnancy (controversial)
  • Lower extremities Doppler ultrasound to rule out DVT
  • Echocardiography: may demonstrate right ventricular dysfunction in acute PE, predicting a higher mortality and possible benefit from thrombolytic therapy. TEE can visualize large thrombus in pulmonary artery

Figure 206-2. Algorithm If Clinical Suspicion of PE
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Initial (O2, Vasopressors If Needed)

  • Anticoagulation (AC) reduces mortality and is considered a primary therapy for PE:
    • Empiric AC is considered if index of suspicion is high and no contraindication, IV heparin, SC LMWH, or SC fondaparinux can be started before diagnosis is confirmed
    • AC reduces the mortality rate of PE because it slows or prevents clot progression and reduces the risk of further embolism
    • Prompt effective AC ...

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