Pulmonary Embolism

Pulmonary Embolism Overview

  • Pulmonary embolism (PE) is a condition where a blood-borne substance lodges in a branch of the pulmonary artery, obstructing blood flow. This can involve various substances, including thrombus (blood clots), air, fat, or amniotic fluid.

Etiology of Pulmonary Embolism

  • The majority of pulmonary emboli originate from deep vein thrombosis (DVT).

Types of Emboli

  • Thrombus: Blood clots that travel to the lungs from the legs or other parts of the body.

  • Air: Air bubbles that may enter the bloodstream and can cause obstruction in the pulmonary arteries.

  • Fat: Fat globules that can be released into circulation, especially after fractures or orthopedic surgeries.

  • Amniotic Fluid: Rare but serious condition can occur during childbirth.

Etiologic Factors

  • Physiologic Factors Related to Venous Stasis: These factors are summarized in Virchow’s triad:

    1. Venous Stasis: Blood flow slows down, increasing the risk of clot formation.

    2. Venous Endothelial Injury: Damage to the blood vessel lining promotes thrombosis.

    3. Hypercoagulation State: Increased clotting tendency, which can occur due to various factors.

Contributing Conditions

  • Severe trauma or spinal cord injury

  • Major surgeries

  • Myocardial infarction (MI) / congestive heart failure (CHF)

  • Recent childbirth

  • Use of oral contraceptives or hormone replacement therapy

Pathophysiology

  • The effects of a pulmonary embolism depend on the size of the embolus and the degree of blood flow obstruction.

  • Clinical Consequences:

    • Reflex bronchoconstriction occurs in the affected area, impairing gas exchange and resulting in decreased oxygen levels.

    • The loss of alveolar surfactant can lead to further complications.

    • Pulmonary hypertension may develop, although pulmonary infarction (tissue death) due to PE is uncommon.

Manifestations of Pulmonary Embolism

  • Symptoms can vary based on the size of the embolism:

Moderate Size Emboli

  • Breathlessness

  • Pleuritic pain (sharp chest pain that worsens with breathing)

  • Apprehension (feeling of anxiety)

  • Tachycardia (increased heart rate)

  • Increased respiratory rate

Massive Emboli

  • Sudden collapse

  • Severe chest pain

  • Shock (potentially life-threatening condition)

  • Cyanosis (bluish skin due to lack of oxygen)

  • Diaphoresis (sweating)

  • Potentially fatal outcomes.

Diagnosis and Treatment

  • Diagnosis: Several methods are used to confirm pulmonary embolism:

    • D-Dimer: A blood test that can indicate the presence of clot breakdown.

    • Helical (Spiral) CT Scan: Imaging method frequently used to visualize emboli.

    • Arterial Blood Gases (ABGs): Assess gas exchange and oxygenation.

    • Pulmonary Angiography: Considered when non-invasive tests fail to provide adequate results.

  • Treatment Options:

    • Thrombolytic Therapy: Use of medications like streptokinase to dissolve clots.

    • Anticoagulant Therapy: Administration of heparin or warfarin to prevent further clot formation.

    • IVC Filter: A filter placed in the inferior vena cava to prevent clots from reaching the lungs.

Prophylactic Measures

  • Preventative strategies include early ambulation (moving and walking) and using compression stockings to improve venous return and reduce stasis.