Differentiating Between Asthma, COPD, and Bronchiectasis
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|← Block C4 - Adolescence and Adulthood|
- Asthma, COPD, and bronchiectasis are diseases that cause chronic inflammation of the airways but have distinct characteristics.
- The American Thoracic Society defines COPD as "a group of lung conditions that make it difficult to empty the air out of the lungs":
- Chronic bronchitis:chronic productive cough for three months in each of two successive years in a patient in whom other causes of chronic cough (eg, bronchiectasis) have been excluded.
- Emphysema: abnormal and permanent enlargement of the airspaces distal to the terminal bronchioles that is accompanied by destruction of the airspace walls, without obvious fibrosis (ie, there is no fibrosis visible to the naked eye).
- A majority of COPD patients have both emphysema and chronic bronchitis. 40% of people with COPD also have asthma.
- COPD and asthma are often comorbid with: high blood pressure, impaired mobility, insomnia, sinusitis, migraine, depression, stomach ulcers, cancer. (20% have 3+ comorbidities).
- Bronchiectasis requires two conditions: An infectious insult; impaired drainage, airway obstruction, or a defect in host defense.
|Obstructive Lung Diseases|
|Ages affected||Childhood||Adulthood||Prevalence increases with age, more common in women.|
|Exacerbation triggers||Allergens, cold air, exercise.||Respiratory tract infections (flu, pneumonia), pollutants.|
|Reversible lung function||Yes. Controlled asthmatics have normal spirometry results.||No. Never fully.||No.|
|Etiology||Correlated with Western lifestyle: increased hygiene reduces exposure to allergens and decreases natural desensitization. Induced by animal/plant proteins and by organic/inorganic chemical agents.||Smoking.||Mainly rheumatic disease (rheumatoid arthritis, Sjögren's syndrome, Crohn disease), allergic bronchopulmonary aspergillosis, immunodeficiency, hematologic malignancy, aspiration, and nontuberculous mycobacterial infection. May also result from infective and acquired causes, e.g. pneumonia, TB, cystic fibrosis.|
|Pathophysiology||Basement-membrane thickening. Hyperplasia of airway smooth muscle and mucus glands. Minimal fibrosis in subepithelial area.||Fibrosis of small airways (peribronchiolar). Destruction of alveolar walls.||The ensuing host response, immune effector cells (predominantly neutrophils), neutrophilic proteases, reactive oxygen intermediates (eg, hydrogen peroxide [H2O2]), and inflammatory cytokines, found in respiratory secretions causes transmural inflammation, mucosal edema, cratering, ulceration, and neovascularization in the airways. The result is permanent abnormal dilatation and destruction of the major bronchi and bronchiole walls.|
|Target tissue||Large airways.||Small airways (alveolar disruption observed).|
|Disease course||Stable (with exacerbations)||Progressive worsening (with exacerbations)|
|Signs and Symptoms, and Diagnosis|
|Diagnosis criteria||Post-bronchodilator FEV1 <80% and FEV1/FVC <70%. (FEV1 = Forced expiratory volume in 1 second, FVC = Forced vital capacity).|
|Predominant inflammatory cells||Eosinophils, (activated) mast cells, CD4+ T-lymphocytes, IL-4, IL-5, dendritic cells.||Neutrophils, macrophages, CD8 T lymphocytes.|
|Breathing||Dyspnea. Airflow obstruction is intermittent.||Dyspnea. Airflow obstruction is more permanent.
||Dyspnea. Auscultation may show crepitations and expiratory rhonchi.|
|Airway hyper-responsiveness||Yes.||Yes.||Only a subgroup of patients.|
|Cough||Episodes of wheezing and chest tightness (especially at night: 2am-6am). Usually little or no sputum production.||Daily morning cough that produces phlegm: characteristic of chronic bronchitis, a type of COPD.||Daily production (up to 240ml/day) of mucopurulent (often green/yellow) and tenacious sputum lasting months to years. Possible hemoptysis, halitosis.|
|Heart-rate||Increased during exacerbation episodes: mild (<100), moderate (100-120), severe (>120).|
|Cure||No cure but can be managed with meds and avoiding triggers.||No cure. Damage irreversible. Can be managed and slowed using meds and lifestyle changes.|
|Bronchodilators||Used only as needed||Regular therapy|
|Exercise training||Rarely used.||Essential therapy.|
|Inhaled corticosteroids||Essential therapy||Only used in moderate and severe cases|
|End-of-life discussion||Not necessary.||Necessary.|