Chronic Obstructive Pulmonary Disease

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Basics

Description

  • Third leading cause of death in the U.S.
  • A disease characterized by airflow obstruction due to several processes:
    • Emphysema: Irreversible alveolar destruction with loss of airway elastic recoil
      • Represents accelerated aging of the lung
    • Chronic bronchitis: Airway inflammation without alveolar destruction
    • Reactive airway disease: Reversible bronchospasm, mucous plugging, and mucosal edema
  • COPD affects ∼10% of the population and 50% of smokers
  • Increased incidence of hypertension, diabetes, heart failure, and cardiovascular disease in those with COPD
  • Frequent exacerbations lead to:
    • Greater mortality
    • Faster decline in lung function
    • Worse quality of life
    • Increased risk of hospitalization
  • Modified Medical Research Council (mMRC) dyspnea scale:
    • Grade 0: Only breathless with strenuous exercise
    • Grade 1: Short of breath when hurrying or walking up a slight hill
    • Grade 2: Walk slower than people of same age due to dyspnea or have to stop for breath when walking on level ground
    • Grade 3: Stop for breath after 100 m on level ground
    • Grade 4: Too breathless to leave the house or breathless when dressing/undressing
  • GOLD guidelines:
    • Group A:
      • No more than 1 exacerbation/yr
      • FEV1 >80% predicted
      • mMRC of 0 or 1
    • Group B:
      • mMRC of 2 or more
      • FEV1 50–80% of predicted
    • Group C:
      • mMRC <2
      • ≥2 exacerbations/yr
      • FEV1 30–49% of predicted
    • Group D:
      • High symptom burden
      • mMRC ≥2
      • High risk for exacerbations
      • FEV1 <30% of predicted

Risk Factors

Genetics
α1-antitrypsin deficiency

Etiology

  • Smoking is the overwhelming cause:
    • COPD develops in 15% of smokers
  • Air pollution
  • Airway hyperresponsiveness
  • α1-antitrypsin deficiency
  • Autoimmunity may play a role
  • Acute exacerbations:
    • Viral infections:
      • >50% of exacerbations associated with recent cold symptoms
      • Decreased immunity may make the host more susceptible to a COPD exacerbation
      • Rhinovirus
      • Respiratory syncytial virus (RSV)
    • Bacterial infections:
      • Bacteria isolated in 40–60% of sputum during acute exacerbation
      • Most common:
        • Haemophilus influenzae
        • Moraxella catarrhalis
        • Streptococcus pneumoniae
      • More likely if:
        • Increased dyspnea
        • Increased sputum volume
        • Purulent sputum
    • Pollutants:
      • Changes to immunity
      • Increased airway inflammation
    • Seasonal variations:
      • More common and more severe in winter

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Basics

Description

  • Third leading cause of death in the U.S.
  • A disease characterized by airflow obstruction due to several processes:
    • Emphysema: Irreversible alveolar destruction with loss of airway elastic recoil
      • Represents accelerated aging of the lung
    • Chronic bronchitis: Airway inflammation without alveolar destruction
    • Reactive airway disease: Reversible bronchospasm, mucous plugging, and mucosal edema
  • COPD affects ∼10% of the population and 50% of smokers
  • Increased incidence of hypertension, diabetes, heart failure, and cardiovascular disease in those with COPD
  • Frequent exacerbations lead to:
    • Greater mortality
    • Faster decline in lung function
    • Worse quality of life
    • Increased risk of hospitalization
  • Modified Medical Research Council (mMRC) dyspnea scale:
    • Grade 0: Only breathless with strenuous exercise
    • Grade 1: Short of breath when hurrying or walking up a slight hill
    • Grade 2: Walk slower than people of same age due to dyspnea or have to stop for breath when walking on level ground
    • Grade 3: Stop for breath after 100 m on level ground
    • Grade 4: Too breathless to leave the house or breathless when dressing/undressing
  • GOLD guidelines:
    • Group A:
      • No more than 1 exacerbation/yr
      • FEV1 >80% predicted
      • mMRC of 0 or 1
    • Group B:
      • mMRC of 2 or more
      • FEV1 50–80% of predicted
    • Group C:
      • mMRC <2
      • ≥2 exacerbations/yr
      • FEV1 30–49% of predicted
    • Group D:
      • High symptom burden
      • mMRC ≥2
      • High risk for exacerbations
      • FEV1 <30% of predicted

Risk Factors

Genetics
α1-antitrypsin deficiency

Etiology

  • Smoking is the overwhelming cause:
    • COPD develops in 15% of smokers
  • Air pollution
  • Airway hyperresponsiveness
  • α1-antitrypsin deficiency
  • Autoimmunity may play a role
  • Acute exacerbations:
    • Viral infections:
      • >50% of exacerbations associated with recent cold symptoms
      • Decreased immunity may make the host more susceptible to a COPD exacerbation
      • Rhinovirus
      • Respiratory syncytial virus (RSV)
    • Bacterial infections:
      • Bacteria isolated in 40–60% of sputum during acute exacerbation
      • Most common:
        • Haemophilus influenzae
        • Moraxella catarrhalis
        • Streptococcus pneumoniae
      • More likely if:
        • Increased dyspnea
        • Increased sputum volume
        • Purulent sputum
    • Pollutants:
      • Changes to immunity
      • Increased airway inflammation
    • Seasonal variations:
      • More common and more severe in winter

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