3- COPD

• COPD


  Common, preventable, and treatable disease characterized by persistent respiratory symptoms and airflow limitations due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases
• COPD (practical definition)

  • >40 years old
  • Significant exposure (10 pack-year smoking history, biomass exposure, certain occupations)
  • No prior diagnosis of asthma
  • Post bronchodilator FEV1/FVC ratio of <70
• Pathophysiology of COPD

  1. Increased # of mucus secreting goblet cells→more mucus secretion

  2. Lymphocytic infiltrate (CD8+)

  3. Ulceration of epithelial layer→squamous cell metaplasia with time

  4. Inflammation→scarring and thickening of walls→fibrosis →airflow limitation
• Risk factors for COPD

  • Smoking
  • Second-hand smoke
  • Alpha1 antitrypsin deficiency
  • Chronic asthma
  • Infections (often the precipitating cause of acute exacerbations)
• Diagnosis of COPD

  • Pulmonary function tests (decreased FEV1 and FEV1/FVC ratio, post bronchodilator FEV1/FVC ratio of <70, decreased vital capacity, increased TLC, residual volume & FRC)
  • Chest x-ray (useful in severe advanced emphysema and acute exacerbations)
  • ABG (hypercapnia, hypoxemia)
  • Alpha 1 antitrypsin level (in patients with family history of premature emphysema)
• Significant reversibility after bronchodilator (200ml AND 12%) does NOT exclude COPD; some people may have variable reversibility
• Chest x-ray (low sensitivity)

  • Useful in severe advanced emphysema which would show hyperinflation, flattened diaphragm, enlarged retrosternal space, diminished vascular markings
  • Useful in acute exacerbations to rule out: pneumonia, pneumothorax
• ABG

  Hypercapnia, hypoxemia
• Alpha 1 antitrypsin level

  In patients with family history of premature emphysema
• Chronic bronchitis

  Chronic productive (sputum) cough of at least 3 months per year for at least 2 consecutive years. (Clinical diagnosis)
• Emphysema


  Permanent enlargement of air spaces distal to terminal bronchioles due to destruction of alveolar walls. (Pathologic diagnosis)
• Pathogenesis of chronic bronchitis

  1. Excess mucus production narrows the airways

  2. Inflammation & scarring in airways + enlarged mucus glands + SM hyperplasia à obstruction
• Pathogenesis of emphysema

  1. Elastase enzyme released by PMNs and macrophages digests the human lung and is usually inhibited by alpha 1 antitrypsin

  2. Decrease in alpha 1 antitrypsin à alveolar wall destruction
• Symptoms

  • Chronic cough
  • Sputum production (white or clear unless infected)
  • Dyspnea, wheeze
  • More prone to infections
• Signs of chronic bronchitis (Blue Bloaters)

  • End-expiratory wheezing on auscultation, decreased breath sounds
  • Hyperresonance on percussion
  • Prolonged expiratory time
  • Usually overweight
  • Cyanosis
  • RR normal
  • Tachycardia
  • Bounding pulse
  • Peripheral vasodilation
  • Course flapping tremor
  • Confusion/drowsiness
• Signs of emphysema (Pink Puffers)

  • Thin due to increased BMR
  • Barrel chest
  • Tachypnea
  • Breathing through pursed lips (to prevent alveolar and airway collapse)
  • Patient in distress with accessory muscle use
• Treatment

  • Smoking cessation (most important)
  • Home oxygen therapy (if pO2 ≤55 or saturation ≤88%; mortality benefit is directly proportional to the number of hours oxygen is used)
  • Influenza and pneumococcal vaccinations
  • Inhaled bronchodilators (anticholinergics ex: ipratropium bromide or B-agonists ex: albuterol, salmeterol or combination of both)
  • If low exacerbation risk: LAMA
  • If frequent exacerbations, highly symptomatic, or eosinophils > 300 à Inhaled corticosteroids + LAMA or LABA
  • Pulmonary rehabilitation
  • Surgery for selected patients (lung resection/transplantation)
• The two types (chronic bronchitis and emphysema) usually coexist
• Complications of COPD

  • Acute exacerbations (due to infections, non-compliance and cardiac problems)
  • Secondary polycythemia (as compensation for chronic hypoxemia)
  • Pulmonary HTN and cor pulmonale
  • Respiratory failure
• Secondary polycythemia


  Compensation for chronic hypoxemia
• Treatment for secondary polycythemia

  Requires venesection if Hct>55%