COPD

COPD is an obstructive persistent, progressive airflow limitation that is not fully reversible, usually caused by chronic exposure to noxious particles (most often cigarette smoke).

• Main Phenotypes:
  • Chronic bronchitis: Productive cough ≥ 3 months/year for ≥ 2 consecutive years.
  • Emphysema: Destruction of alveolar walls → loss of elastic recoil → hyperinflation.

Pathophysiology

• Chronic bronchitis: Inflammation + mucus gland hyperplasia → airway narrowing.
• Emphysema: Protease-antiprotease imbalance (↑ elastase activity in smokers, or α1-antitrypsin deficiency) → alveolar destruction.
• Result: ↓ FEV₁, ↑ residual volume, V/Q mismatch, hypoxia ± hypercapnia in later stages.

Diagnosis

• Gold standard: Spirometry
  • Post-bronchodilator FEV₁/FVC < 0.70 confirms obstruction.
  • ↓ FEV₁ correlates with severity.
• Imaging:
  • CXR: Hyperinflated lungs, flattened diaphragms.
  • CT: Bullae (emphysema).
• Other tests:
  • ABG: Hypoxemia ± hypercapnia in advanced disease.
  • α1-antitrypsin levels if early-onset or minimal smoking history.

GOLD Staging (Post-Bronchodilator)

Management

Lifestyle

• Smoking cessation: Most effective intervention.
• Pulmonary rehab: Improves exercise tolerance and quality of life.
• Vaccines: Influenza + pneumococcal.

Pharmacologic Therapy

Based on symptoms & exacerbations:

1. Short-acting bronchodilators (SABA or SAMA) - for rescue use.
2. Long-acting bronchodilators
   • LABA (salmeterol, formoterol)
   • LAMA (tiotropium) - especially effective for exacerbation prevention.
3. Inhaled corticosteroids (ICS) - for patients with frequent exacerbations despite LABA/LAMA.
4. PDE4 inhibitor (roflumilast) - severe chronic bronchitis phenotype.
5. Theophylline - rarely used due to toxicity.

Oxygen Therapy

• Indications: PaO₂ ≤ 55 mmHg or SpO₂ ≤ 88%, or PaO₂ ≤ 59 mmHg with cor pulmonale/polycythemia.
• Long-term oxygen (>15 hrs/day) improves survival.

Exacerbations

Definition: Acute worsening of respiratory symptoms beyond normal variation.
Common triggers: Infections (viral/bacterial), environmental pollutants.
Management:

• O₂ to keep SpO₂ 88–92%.
• Bronchodilators: Frequent SABA/SAMA.
• Systemic steroids: Prednisone 40 mg daily × 5 days.
• Antibiotics if increased sputum purulence + volume + dyspnea:
  • Outpatient: Azithromycin, doxycycline.
  • Inpatient: Ceftriaxone + azithromycin, or levofloxacin.

Exam & Ward Pearls

• Blue bloater = chronic bronchitis phenotype (hypoxemia, hypercapnia).
  Pink puffer = emphysema phenotype (dyspnea, thin body habitus).
• Always check baseline CO₂ in chronic CO₂ retainers before starting high-flow O₂
  • Rapid correction can cause hypoventilation.
• If the question says “27-year-old nonsmoker with emphysema,” think α1-antitrypsin deficiency.
  • Young patient and nonsmoker
• On the wards, many patients are on triple therapy: LABA + LAMA + ICS.
• COPD is not reversible with bronchodilators
  • In contrast to asthma.