3- COPD

Cards (21)

  • 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%