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Notes on Pulmonary Vascular Embolism and Pulmonary Disease

Chapter 21: Pulmonary Vascular Embolism and Pulmonary Disease

Key Definitions

  • Pulmonary Embolism (PE): Blockage of a pulmonary artery caused by an embolus (a dislodged blood clot).
  • Thrombus: A blood clot that forms in a vein and remains there.
  • Embolus: A blood clot that travels to another part of the body.
  • Pulmonary Infarction: Resulting tissue damage and vessel disruption due to an embolus obstructing blood flow.
  • Saddle Embolus: A large embolus that detaches from a thrombus and lodges in the bifurcation of the pulmonary artery.

Anatomic Alterations of the Lungs

  • Pulmonary Vascular Blockage: Leads to various pathophysiological changes including:
    • Pulmonary hypertension.
    • Cor pulmonale (right heart failure due to lung disease).
    • Pulmonary infarction.
    • Alveolar atelectasis (collapse of lung sections).
    • Alveolar consolidation (fluid or materials in alveoli).
    • Bronchospasm (narrowing of airways).

Etiology and Epidemiology

  • Deep vein thrombosis (DVT) is often a precursor to PE.
    • Symptoms can be vague, making diagnosis challenging.
    • Blood clots commonly originate from DVT sites.
  • Virchow’s Triad represents risk factors contributing to thrombosis:
    1. Venous Stasis: Sluggish blood flow through veins.
    2. Hypercoagulability: Increased tendency of blood to clot.
    3. Endothelial Injury: Damage to blood vessel linings.

Diagnosis and Screening

  • Diagnosis relies on:
    • Clinical manifestations indicating PE presence.
    • Blood tests, particularly D-dimer test to identify clotting.
    • Imaging techniques, including:
    • Chest X-ray.
    • Computed Tomography Pulmonary Angiogram (CTPA).
    • Ventilation-perfusion scans.
    • MRI and MRA.

Clinical Manifestations

  • Common Symptoms:
    • Atelectasis: Lung parts collapse, restricting airflow.
    • Bronchospasm: Wheezing or difficulty breathing.
    • Increased respiratory rate (tachypnea) and heart rate (tachycardia).
    • Hypotension and cyanosis.
    • Coughing with potential hemoptysis (coughing up blood).
  • Physical Exam Findings:
    • Distended neck veins, edema, chest pain, and confusion.
    • Abnormal heart sounds, including increased S2 and possible arrhythmias.

Radiologic Findings

  • Chest Radiography:
    • Increased density in infarcted areas.
    • Hyperradiolucency distal to emboli indicating air trapping.
    • Signs of pulmonary edema and dilation of pulmonary arteries.
    • Possible right ventricular cardiomegaly (enlarged heart due to strain).

Management of Pulmonary Embolism

  1. Initial Care:
    • Transfer to ICU for monitoring.
    • Initiate treatment with anticoagulants like:
      • Heparin (both high and low molecular weight forms).
      • Warfarin for long-term management.
    • Thrombolytics (e.g., Alteplase) to dissolve clots.
  2. Preventive Strategies:
    • Promote mobility (walking, seated exercises).
    • Hydration and the use of compression stockings.
    • Consider inferior vena cava filters in high-risk patients.

Pulmonary Hypertension (PH)

  • Characterized by mean pulmonary artery pressure > 25 mm Hg (normal: 10-20 mm Hg).
  • More prevalent in females with a 3:1 ratio compared to males.
  • Divided into five treatment-based groups.
  • Can be caused by left-sided heart failure, COPD, PE, etc.

Management of Pulmonary Hypertension

  • Focus on symptom management and slowing disease progression:
    • Diuretics for fluid retention.
    • Phosphodiesterase Inhibitors and blood thinners to prevent clots.
    • Oxygen Therapy and exercise to improve tolerance.
    • Emerging treatments like inhaled gas therapies such as Iloprost and Treprostinil.

Importance of Early Detection

  • Many cases of PE and PH are asymptomatic until advanced stages.
  • Regular screening and awareness of risk factors are crucial for effective management.