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  • • Deep venous thrombosis (DVT) most common source of pulmonary embolism (PE)

    • Uncommon causes of embolism include:

    • -Air (complications from central lines)

      -Fat (long bone fractures, respiratory insufficiency, coagulopathy, encephalopathy, petechiae)

      -Amniotic (during active labor)

      -Tumor emboli from RA or inferior vena cava (IVC)

    • < 10% of PE cause pulmonary infarction

    • Size and frequency of PE determines disease and outcome

    • PE obstructing large pulmonary artery: RV failure

    • PE causes release of vasoactive amines causing severe pulmonary vasoconstriction, increased dead space and hypoxia from right-to-left shunt

    • Reflex bronchial vasoconstriction common

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Epidemiology

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  • • 50,000 deaths yearly in United States

    • Third leading cause of death in hospital patients

    • Only 30-40% have suspected DVT

    • PE develops in 60% of untreated proximal lower extremity DVT

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Symptoms and Signs

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  • • Dyspnea and chest pain (present in 75%)

    • Tachycardia, tachypnea, altered mental status

    • Classic triad: Dyspnea, chest pain, hemoptysis (15%)

    • Pleural rub and S1Q3T3 rarely found

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Laboratory Findings

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  • ABG measurement: Hypoxia with respiratory alkalosis

    ECG: New onset atrial fibrillation, ST/T wave changes, sinus tachycardia

    • Elevated D-dimer levels

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Imaging Findings

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  • Chest film: Often normal, may show pulmonary cap

    ECG: May show atrial fibrillation, ischemic changes, or RV strain (S1Q3T3), but usually only sinus tachycardia.

    V̇/Q̇ scan: Sensitivity & specificity of 90%, however, 67% of studies are inconclusive

    Spiral CT: More accurate than V̇/Q̇ scan

    Magnetic resonance angiography: Excellent sensitivity and specificity

    Pulmonary angiogram: Invasive but gold standard

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  • • Evaluate for other causes of chest pain and hypoxia, such as pneumonia

    • Evaluation may be clouded by other possibilities including postoperative pneumonia, which can make V̇/Q̇ scan nondiagnostic

    • Spiral CT of chest most sensitive and efficient in postoperative patient

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  • • ABG measurement

    • Chest film

    • Duplex Doppler of lower extremity

    • V̇/Q̇ scan (often inconclusive), cannot be interpreted in face of abnormal chest film

    • Spiral CT of chest accuracy better than V̇/Q̇ and does not need clinical correlation

    • Magnetic resonance pulmonary angiogram

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  • • Initial stabilization with pressors and ventilatory support

    • Start heparin/low-molecular-weight heparin expediently

    • Consider thrombolytics if large clot burden, sever respiratory compromise, hemodynamic instability

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Surgery

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  • • IVC filter

    • Open surgical thrombectomy: High mortality (Trendelenburg procedure)

    • Catheter-based suction embolectomy: only in experienced operators

    • Extracorporeal membrane oxygenation (ECMO) can be a last resort in a critical situation

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Indications

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  • • IVC filter

    • -Contraindication to anticoagulation

      -Venous thrombosis extension on anticoagulation

    • Open pulmonary embolectomy

    • -Intractable hemodynamic instability

      -Thrombolytics inadequate or not available

      -Rarely indicated or useful

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Prognosis

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  • • Preventable cause of hospital death

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Prevention

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  • • DVT prophylaxis in perioperative period

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References

The PREPIC study group: ...

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