Medical Lecture Notes: Emphysema

 

📘 Medical Lecture Notes: Emphysema

🟢 Definition:

Emphysema is a chronic, progressive lung disease characterized by irreversible destruction of alveolar walls, leading to permanent enlargement of airspaces distal to terminal bronchioles, without obvious fibrosis. It is a major form of Chronic Obstructive Pulmonary Disease (COPD).

🔍 Etiology / Risk Factors:

• Cigarette Smoking – most common cause
• Air Pollution & Occupational Exposure – e.g., silica, cadmium
• Alpha-1 Antitrypsin Deficiency – genetic, in young non-smokers
• Aging – decline in lung elasticity
• Chronic Infections – recurrent airway inflammation

🧬 Pathophysiology:

Inhaled toxins (like cigarette smoke) trigger chronic inflammation, causing release of proteolytic enzymes (e.g., elastase), which destroy alveolar walls and elastin.
➤ Loss of elastic recoil → air trapping
➤ Destruction of capillaries → impaired gas exchange
➤ Alveolar coalescence → reduced diffusion surface

📑 Types of Emphysema:

• Centriacinar (Centrilobular): Affects respiratory bronchioles, mostly in upper lobes, linked to smoking.
• Panacinar (Panlobular): Affects entire acini, especially in lower lobes. Seen in α1-antitrypsin deficiency.
• Paraseptal (Distal Acinar): Involves distal acinus near pleura. Can lead to spontaneous pneumothorax in young adults.

🧪 Clinical Features:

• Progressive dyspnea (initially on exertion)
• Pursed-lip breathing
• Barrel-shaped chest (hyperinflation)
• Decreased breath sounds, hyperresonance on percussion
• Accessory muscle use in respiration
• Minimal cough, scanty sputum
• "Pink puffer" appearance:
  • Dyspnea with normal PaCO₂
  • No cyanosis until late

📷 Radiologic Findings:

• Hyperinflated lungs
• Flattened diaphragm
• Increased retrosternal air space
• Bullae or blebs in advanced disease

🧫 Pulmonary Function Test (PFT):

• ↓ FEV₁
• ↓ FEV₁/FVC ratio (<70%)
• ↑ TLC (Total Lung Capacity)
• ↑ RV (Residual Volume)
• ↓ DLCO (due to alveolar wall destruction)

🧬 Alpha-1 Antitrypsin Deficiency Clue:

• Onset < 45 years
• Minimal or no smoking history
• Family history of lung/liver disease
• Panacinar emphysema in lower lobes

🧾 Diagnosis:

• Detailed history and physical exam
• PFTs to confirm airflow obstruction
• Chest X-ray or HRCT to detect emphysema
• Serum α1-antitrypsin (if deficiency suspected)
• ABG in advanced cases: may show hypoxemia/hypercapnia

💊 Management:

1. Lifestyle Modifications
   • Smoking cessation – most important
   • Avoid pollutants
   • Pulmonary rehab programs
2. Medications
   • Bronchodilators (β2-agonists, anticholinergics)
   • Inhaled corticosteroids (for exacerbations)
   • Phosphodiesterase-4 inhibitors (e.g., roflumilast)
   • Long-term oxygen therapy (if chronic hypoxemia)
   • Annual flu and pneumococcal vaccines
3. Surgical Treatments
   • Lung Volume Reduction Surgery (LVRS)
   • Bullectomy (for large bullae)
   • Lung transplantation (in select patients)

🚨 Complications:

• Respiratory failure
• Spontaneous pneumothorax
• Pulmonary hypertension
• Cor pulmonale (right-sided heart failure)

📌 Prognosis:

Emphysema is irreversible but proper management can improve quality of life.
The BODE index (BMI, Obstruction, Dyspnea, Exercise capacity) helps predict survival and disease severity.

🔎 Key Differences: Emphysema vs. Chronic Bronchitis

Feature	Emphysema	Chronic Bronchitis
Primary Symptom	Dyspnea	Productive cough
Appearance	Thin, "pink puffer"	Overweight, "blue bloater"
Cyanosis	Late	Early
Cough	Mild, dry	Prominent
DLCO	Decreased	Normal

🧠 Summary Points:

• Emphysema = chronic destruction of alveoli + airspace enlargement
• Smoking cessation is the most effective intervention
• Medical and surgical therapies can improve symptoms but not cure
• PFTs and imaging are essential for diagnosis and classification