COPD (Chronic Obstructive Pulmonary Disease) includes Emphysema and Chronic Bronchitis – How are these 2 conditions different, yet similar?

General Features and Symptoms of COPD:

• Gradual onset: Symptoms develop slowly over time.
• Main signs:
  • Shortness of breath (dyspnea).
  • Increased respiratory rate (tachypnea).
  • Barrel chest (due to hyperinflation of lungs).
  • Prolonged expiratory phase—difficulty exhaling due to loss of alveolar elasticity.
  • Weight loss and anorexia: Inflammation causes loss of appetite and energy diversion to breathing.
  • Chronic hypoxia: Leads to clubbing (enlargement of fingertips and toes).
  • Physical appearance: Often diagnosed through chest X-ray and spirometry.

Key Features of Emphysema:

• Progressive lung destruction: Loss of alveolar walls, leading to large, permanently inflated alveolar spaces (bullae and blebs).
• “Pink puffers”: Patients are often pink (due to maintained oxygenation) and exhibit pursed-lip breathing and barrel-chested appearance.
• Cause: Mostly smoking; genetic deficiency of alpha-1 antitrypsin in rare cases.
• Pathology details:
  • Loss of alveolar septae and elastic fibers.
  • Enlargement of air spaces (centriacinar and panacinar types).
  • Decreased recoil, increased air trapping, and hyperinflation.
• Imaging: Chest X-ray shows hyperinflated lungs, flat diaphragm, and bullae.

Key Features of Chronic Bronchitis:

• Chronic inflammation: Persistent airway inflammation causing mucus hypersecretion.
• Diagnosis: Chronic productive cough lasting ≥3 months for two consecutive years.
• Pathology:
  • Hypertrophy and hyperplasia of goblet cells (mucus-producing cells).
  • Thickening of the bronchial walls and lumen narrowing.
  • Air trapping resulting in hypoxia and cyanosis (“blue bloaters”).
• Signs: Cyanosis, sputum production, and signs of right-sided heart failure (cor pulmonale).

Pathophysiology & Consequences:

• Lung damage:
  • Loss of alveolar surface area reduces gas exchange.
  • Air trapping and hyperinflation cause barrel-chested appearance.
• Pulmonary hypertension:
  • Narrowed, vasoconstricted pulmonary vessels increase resistance.
  • Elevated pulmonary artery pressure strains the right heart, leading to right-sided heart failure (cor pulmonale).
• Hypoxia and hypercapnia:
  • Reduced oxygen causes cyanosis.
  • CO₂ retention causes acidosis.
• Polycythemia:
  • Kidneys respond to hypoxia by increasing erythropoietin, leading to increased red blood cell production and thicker blood.
• Recurrent infections:
  • Chronic mucus pooling and damaged defenses predispose to bacterial infections, such as tuberculosis or secondary infections in immunosuppressed states (AIDS).

Radiographic Features:

• X-ray and CT findings:
  • Hyperinflated lungs.
  • Bullae or blebs (large air spaces from alveolar wall destruction).
  • Bronchiectasis—damage causes dilation of bronchi susceptible to collapse.
  • Collapsed alveoli due to mucus plugging, worsening hypoxia.

Ventilation-Perfusion & Pulmonary Hypertension:

• Ventilation-perfusion mismatch:
  • Low oxygen levels cause pulmonary vasoconstriction (reflex).
  • Widespread vasoconstriction increases pulmonary artery pressure, causing pulmonary hypertension.
  • Elevated pressures stress the right heart, leading to cor pulmonale.

The Role of Mucus, Obstruction, and Infections:

• Mucus pooling can lead to airway blockages, especially overnight.
• Infections further damage lungs; bacteria can invade damaged alveoli.
• Pneumothorax: Rupture of bullae can cause air to enter the pleural space, collapsing the lung.

Key Symptoms:

• Shortness of breath, cough, tachypnea, and wheezing.
• Thick, purulent sputum (especially during infection).
• Cyanosis (blue coloration of lips and fingernails).
• Barrel chest and hyperinflation.
• Possible clubbing of fingers.

Management Strategies:

• Prevention:
  • Stop smoking.
  • Minimize exposure to environmental irritants and pollutants.
  • Vaccinations: Influenza and pneumococcal vaccines.
• Mucus clearance:
  • Postural drainage, percussion therapy (clapping), and expectorants.
• Medications:
  • Bronchodilators (e.g., inhaled beta-agonists, anticholinergics).