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.