Lecture Notes: Emphysema and COPD

Introduction

• Definition of Emphysema: "Inflate or swell"
  • Involves damage or destruction of alveolar air sacs in lungs.
  • Alveoli enlarge and lose elasticity, causing difficulty in exhaling.

Emphysema and COPD

• COPD: Chronic Obstructive Pulmonary Disease includes emphysema and chronic bronchitis.
  • Emphysema: Defined by structural changes (enlargement of air spaces).
  • Chronic Bronchitis: Defined by clinical features (productive cough).
  • Common cause: Smoking.

Lung Function in COPD

• Airway Obstruction: Lungs don’t empty properly, leading to air trapping.
• Reduced FVC and FEV1:
  • FVC (Forced Vital Capacity): Maximum air exhaled in a breath.
  • FEV1 (Forced Expiratory Volume in one second): Reduced more than FVC.
  • FEV1/FVC Ratio: Lower in COPD.
  • Example: Normal FVC 5L, FEV1 4L (80%). COPD FVC 4L, FEV1 2L.
• Increased TLC (Total Lung Capacity): Due to air trapping.

Pathophysiology of Emphysema

• Destruction of Alveoli: Causes poor gas exchange.
• Inflammatory Reaction: Triggered by irritants like cigarette smoke.
  • Inflammatory chemicals: Leukotriene B4, IL-8, TNF alpha, proteases.
  • Breakdown of structural proteins: Collagen and elastin.
  • Consequences:
    • Airway collapse during exhalation.
    • Air trapping.
    • Increased lung compliance (lungs expand easily but retain air).

Types of Emphysema

• Centriacinar Emphysema (Centrilobular): Most common; affects proximal alveoli.
  • Associated with smoking; affects upper lobes.
• Panacinar Emphysema: Affects entire acinus.
  • Associated with alpha-1 antitrypsin deficiency; affects lower lobes.
• Paraseptal Emphysema: Affects distal alveoli near interlobular septa.
  • Can lead to pneumothorax.

Symptoms and Diagnosis

• Symptoms: Dyspnea, cough with minor sputum, weight loss.
  • "Pink Puffers": Shortness of breath, pursed lip breathing.
• Physical Signs: Barrel-shaped chest, flattened diaphragm on x-ray.
• Complications: Hypoxemia, pulmonary hypertension, cor pulmonale (right-sided heart failure).

Treatment

• Reducing Risk Factors: Quitting smoking.
• Medications:
  • Bronchodilators, inhaled steroids, antibiotics.
• Supplemental Oxygen: Helps manage symptoms.

Summary

• Emphysema: A type of COPD caused by irritants breaking down elastin, leading to air trapping and poor gas exchange.

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This summary covers the key aspects of emphysema and its relationship with COPD, including physiological changes, types, symptoms, diagnosis, and management strategies.