COPD Lecture Notes

Introduction

• COPD: Chronic Obstructive Pulmonary Disease
• Part of the clinical medicine section
• Two types: Chronic Bronchitis and Emphysema

Chronic Bronchitis

Clinical Presentation

• Productive cough (common presentation)
• Dyspnea
• Wheezing and rhonchi on physical exam

Pathophysiology

• Inflammation and fibrosis in airways
  • Excessive mucus production
  • Airway narrowing and obstruction
  • Irreversible fibrosis
  • Bronchospasm
• Difficulty primarily in getting air out

Causes

• Major cause: Smoking
• Inflammatory cells: Neutrophils, CD8 lymphocytes, macrophages
  • Release cytokines and growth factors

Emphysema

Clinical Presentation

• More likely dyspnea than productive cough
• Barrel chest (increased AP diameter)
• Decreased breath sounds

Pathophysiology

• Tissue destruction: alveolar septal and elastic tissue destruction
• Bronchial collapse
• Air trapping and hyperinflation
• Causes include smoking and Alpha-1 antitrypsin deficiency (affects lower lobes)
• Noted differences: enlarged air sacs and hyperinflated lungs

Complications of COPD

Chronic Bronchitis

• Pneumonia: Due to airway obstruction and cilia destruction
• Respiratory failure: Often triggered by viral upper respiratory tract infections, leading to hypercapnia and hypoxemia
• Pulmonary hypertension: Due to hypoxemia-induced pulmonary vasoconstriction
• Cor pulmonale: Right heart failure due to chronic pulmonary hypertension
• Polycythemia: Increased erythropoietin production due to chronic hypoxemia

Emphysema

• Pneumonia: Though less common than in chronic bronchitis
• Respiratory failure: Commonly hypercapnia driven (Type 2 respiratory failure)
• Bullae formation: Can lead to secondary spontaneous pneumothorax

Diagnosis

• Chest X-ray: Increased AP diameter, hyperinflation, flat diaphragm
• ECG: Signs of right ventricular hypertrophy and right axis deviation
• ABG: Respiratory acidosis, elevated CO2, low O2
• Pulmonary Function Tests (PFTs): Key test
  • FEV1/FVC ratio < 70%
  • Post-bronchodilator FEV1 increase < 12% suggests COPD over asthma
  • Lung volumes: increased TLC, FRC, RV
  • DLCO: Low in emphysema, normal in chronic bronchitis
• Types of Emphysema:
  • Centrilobular: Upper lobes (smoking related)
  • Panlobular: Lower lobes (Alpha-1 antitrypsin deficiency)

Treatment

Reducing Mortality

• Smoking cessation
• Vaccinations: Flu and pneumococcal
• Oxygen therapy: For chronic hypoxemia, to prevent right heart failure (aiming for 88-92% SpO2)

Symptomatic Management

• Bronchodilators and Corticosteroids:
  • Mild (Gold group A): SABA (like albuterol) or SAMA (like ipratropium)
  • Moderate to severe: LABA (sal-meterol) + LAMA (tiotropium)
  • Severe cases with hospitalizations or high eosinophil counts: Add ICS (budesonide, fluticasone)

Acute Exacerbations

• Bronchodilation: Combination of SAMA (ipratropium) and SABA (albuterol) - DuoNeb
• Corticosteroids: Systemic Po or IV steroids
• BiPAP: To reduce work of breathing
• Antibiotics: Azithromycin or doxycycline for bacterial colonization

Summary

• COPD is a chronic, progressive inflammatory disease primarily caused by smoking.
• It involves two main types: chronic bronchitis and emphysema, with overlapping clinical features.
• Diagnosis involves clinical history, imaging, and pulmonary function tests.
• Management focuses on smoking cessation, vaccinations, bronchodilator therapy, and managing acute exacerbations.