Problem 3.06

• Obstructive pulmonary disease


  Characterized by an increase in resistance to air flow caused by partial or complete obstruction at any level

  
• Restrictive pulmonary disease


  Characterized by reduced expansion of lung parenchyma and decreased total lung capacity

  
• Forced vital capacity (FVC)

  Either normal or slightly decreased in obstructive disease
• Forced expiratory volume at 1 second (FEV1)

  Significantly decreased in obstructive disease
• FEV/FVC ratio


  Characteristically decreased in obstructive disease
• FVC


  Reduced in restrictive disease
• FEV/FVC ratio


  Near normal in restrictive disease
• Bronchial asthma


  Increased responsiveness of tracheobronchial tree to a variety of stimuli resulting in widespread spasmodic narrowing of the air passages

  
• Extrinsic/Atopic/Allergic asthma


  Most common form, induced by inhaled antigens, usually seen in children

  
• Intrinsic/Non-atopic/Idiosyncratic asthma


  Bronchial hyperreactivity precipitated by non-immune mechanisms, low threshold of sub-epithelial vagal receptors

  
• Infectious asthma


  Viral respiratory tract infections rather than allergic stimulus as a common precipitating factor, especially in children under 2

  
• Exercise-induced asthma


  More rapid ventilation and colder/drier air breathed increases likelihood of attack, may be due to mediator release or vascular congestion
• Occupational asthma


  Occurs after repeated exposure to various fumes, organic materials, chemicals, gases, and biological enzymes, IgE stimulation and autonomic nervous system overactivity
• Drug-induced asthma


  Bronchospasm occurs mostly in patients with known asthma, best-known offender is aspirin

  
• Emphysema


  Condition characterized by abnormal permanent enlargement of the airspaces distal to the terminal bronchiole, accompanied by destruction of their walls and without obvious fibrosis

  
• Types of emphysema


  • Centriacinar
  • Panacinar
  • Distal acinar/paraseptal
  • Irregular/paracicatricial
  • Mixed (unclassified)
• Oxidative stress and protease-antiprotease hypothesis


  Two major pathogenic mechanisms of emphysema
• Pink puffer


  Well oxygenated, tachypneic emphysema patient
• Chronic bronchitis


  Diagnosed by persistent productive cough for at least 3 consecutive months in at least 2 consecutive years

  
• Simple chronic bronchitis


  Patients have a productive cough but no physiologic evidence of airflow obstruction

  
• Chronic asthmatic bronchitis


  Individuals may demonstrate hyperreactive airways with intermittent bronchospasm and wheezing

  
• Obstructive chronic bronchitis


  Patients develop chronic airflow obstruction, usually with associated emphysema

  
• Pathogenesis of chronic bronchitis

  1. Impaired ciliary function

  2. Hypertrophy of mucous glands and goblet cell metaplasia

  3. Increased secretion of mucus

  4. Airway damage and plugging

  5. Fibrosis of walls

  6. Smooth muscle hypertrophy and squamous metaplasia

  7. V/Q mismatch and pulmonary hypertension

  8. Right heart failure

  
• Blue bloater


  Cyanotic, volume overloaded chronic bronchitis patient
• Bronchiectasis


  Disease characterized by permanent dilation of bronchi and bronchioles caused by destruction of the muscle and elastic tissue, resulting from or associated with chronic necrotizing infections
• Bronchiectasis is uncommon now due to good control of lung infections and use of antibiotics

  
• Etiologies associated with bronchiectasis

  • Post-infectious conditions (TB, Staph aureus)
  • Bronchial obstruction (tumor, foreign body)
  • Chronic diseases (SLE, RA)
  • Congenital conditions (cystic fibrosis, primary ciliary dyskinesia)

  
• Bronchiectasis


  A disease characterized by permanent dilation of bronchi and bronchioles (> 2 mm in diameter) caused by destruction of the muscle and elastic tissue, resulting from, or associated with chronic necrotizing infections
• Causes of bronchiectasis


  • Postinfectious conditions: TB + Staph aureus infection, viral (adenovirus)
  • Bronchial obstruction: tumor, FB
  • Chronic disease: SLE, RA
  • Congenital: cystic fibrosis, primary ciliary dyskinesia

  
• Pathogenesis of bronchiectasis


  1. Bronchial obstruction

  2. Pooling of secretions distal to obstruction

  3. Inflammation of airway

  4. Destruction of bronchial wall

  5. Distal bronchi + bronchioles scarred + obliterated

  6. Collapse of distal lung parenchyma

  
• Pathogenesis of bronchiectasis


  1. Severe infection

  2. Inflammation with necrosis (damage to airway walls)

  3. Heal via fibrosis

  4. Dilation of airways

  
• Bronchiectasis


  • Uncommon now due to good control of lung infection and use of antibiotics

  
• Clinical features of bronchiectasis

  • Chronic productive cough
  • Copious mucopurulent sputum (foul smelling)
  • Hemoptysis
  • Dyspnea & wheezing
  • Chronic hypoxia
  • Pulmonary hypertension

  
• 1. ray of bronchiectasis shows dilated bronchi with thickened walls

  
• Bronchiectasis affects lower lobes bilaterally, particularly vertical air passages and most severe in distal tree
• On cut section, dilated bronchi & bronchioles can be followed up to the pleural surfaces, with cysts filled with mucopurulent secretions
• Microscopic features of bronchiectasis include inflammation (inflammatory cells), desquamation in epithelial lining & necrotizing ulceration, pseudostratification of columnar cells or squamous metaplasia of remaining epithelium, and lung abscess

  
• Fibrosis of the bronchial walls is also a feature of bronchiectasis
• Complications of bronchiectasis


  • Recurrent pneumonia requiring hospitalization
  • Empyema
  • Lung abscess
  • Progressive respiratory failure
  • Cor pulmonale
  • Chronic bronchial infection
  • Pneumothorax
  • Life-threatening hemoptysis (uncommon)

  
• Asthma


  Common obstructive airways disease characterised by reversible airways narrowing due to bronchial mucosal inflammation