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%