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Snapshot
  • A 29-year-old man presents to the emergency department with severe pleuritic chest pain. He tells the resident that he is worried he might have another collapsed lung. His temperature is 98.7°F (37.1°C), blood pressure is 118/78 mmHg, pulse is 119/min, respirations are 31/min, and oxygen saturation is 85% on room air. On examination, he appears cachectic. A chest radiograph is obtained. 
Introduction
  • Clinical definition
    • chronic obstructive pulmonary disease (COPD) is defined as persistent airflow limitation due to mixture of small airway disease and parenchymal destruction
      • early classifications distinguished emphysema and chronic bronchitis
      • no longer distinguished but helpful to separate for pathophysiologic understanding and clinical management
    • emphysema is defined by alveolar wall destruction and dilation that presents in 2 forms
      • centrilobular
        • almost always due to smoking
      • panlobular/panacinar
        • rare and caused by alpha-1-antitrypsin deficiency
          • misfolded alpha-1-antitrypsin (AAT), which normally inhibits elastase
          • without AAT, elastase is over active and destroys elastic tissues
          • can accumulate in hepatocytes and cause cirrhosis
  • Epidemiology
    • demographics
      • males > females
      • 4th most common cause of death globally
    • risk factors
      • tobacco use (most common)
      • air pollution
      • occupational exposure
      • AAT deficiency
  • Pathogenesis
    • damage to airways distal to terminal bronchiole (i.e., acinus)
    • abnormal dilation of airspaces and destruction of alveoli walls due to proteinases (i.e., elastase)
    • decreased alveolar and capillary surface area, which decreases gas exchange
Presentation
  • Symptoms 
    • dyspnea
    • mild cough
    • fatigue
    • hyperventilation
  • Physical exam
    • "pink puffers"
      • non-cyanotic
      • cachectic
      • pursed-lip breathing
    • accessory muscle use
    • hypoxia
    • barrel chest
    • decreased breath sounds
    • end-expiratory wheezing and/or prolonged expiration
    • signs of cirrhosis if associated with AAT deficiency
Studies
  • Diagnostic testing
    • imaging
      • chest radiograph
        • not required for routine diagnosis
        • hyperinflation/flattened diaphragm
        • bullae and/or blebs
        • may have decreased lung markings
      • computed tomography
        • not necessary for management but can determine classification of emphysema (centrilobular or panacinar)
    • studies
      • pulmonary function tests (PFTs) 
        • best initial test
        • decreased FEV1 / FVC (< 0.7) that is incompletely reversible
          • obstructive pattern
          • diagnostic
          • FEV1 = forced expiratory volume
          • FVC = forced vital capacity
        • decreased % FEV1
          • used to categorize severity based on Global initiative for chronic Obstructive Lung Disease (GOLD)
            • mild: > 80%
            • moderate: 50-79%
            • severe: 30-49%
            • very severe: < 30%
        • normal or decreased FVC
        • increased total lung capacity (TLC)
          • more than with chronic bronchitis
        • decreased DLCO (vs. normal in chronic bronchitis)
          • DLCO = diffusing capacity of the lungs for carbon monoxide
      • arterial blood gas (ABG)
        • indicated for O2 saturation < 92%, altered mental status, or acute exacerbation
        • hypoxemia
          • decreased PO2
          • may cause increased hemoglobin/polycythemia
        • acute or chronic respiratory acidosis
          • increased PCO2 (hypercapnia) due to retention
Differential
  • Asthma 
    • distinguishing factor
      • obstructive pattern on PFTs are reversible after administration of inhaled bronchodilator
  • Bronchiectasis 
    • distinguishing factor
      • computed tomography (CT) is gold standard for diagnosis
        • large internal bronchial diameter, thickened bronchial wall, and altered airway geometry
        • "tram-track" and "signet-ring" signs
  • Interstitial lung disease (ILD) 
    • distinguishing factor
      • restrictive lung pattern on PFTs

 

Treatment
  • First-line
    • conservative
      • smoking cessation
        • greatest impact on mortality
      • home O2
        • indicated if resting PaO2 < 55 mmHg or SaO2 <89%
      • flu and pneumococcal vaccines
    • pharmacological 
      • step-wise depending on GOLD classification of disease severity
        • mild
          • short-acting inhaled bronchodilators
          • short-acting inhaled beta-agonist (e.g., albuterol) as needed
          • short-acting inhaled anticholinergic (e.g., ipratropium) as needed
          • most patients will present in more advanced stages
        • moderate
          • long-acting inhaled bronchodilator
          • long-acting beta-agonist (e.g., salmeterol or formoterol)
          • long-acting anticholinergic (e.g., tiotropium)
          • can be used in combination
        • severe
          • inhaled corticosteroid (e.g., budesonide or fluticasone) + long-acting bronchodilator
        • very severe
          • triple therapy
            • inhaled corticosteroid + long-acting anticholinergic + long-acting beta-agonist
          • may require roflumilast
            • phosphodiesterase (PDE)-4 inhibitor
          • theophylline
            • PDE inhibitor and adenosine receptor blocker
            • indicated for severe and refractory disease
            • low therapeutic index
        • AAT deficiency
          • IV pooled AAT
  • Second-line
    • lung resection or transplantation
      • may be beneficial in severe cases refractory to medical management

 

Complications
  • Acute exacerbation   
  • Pneumothorax 
    • caused by rupture of bullae

 

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