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- Chronic, reversible inflammatory airway disease characterized by recurrent attacks of breathlessness and wheezing
- 4 major classifications of asthma severity used primarily to initiate therapy (1,2):
- Intermittent: Symptoms ≤2 d/wk, nighttime awakenings ≤2×/month, short-acting β-agonist use ≤2 d/wk, no interference with normal activity, and normal forced FEV1 between exacerbations with FEV1 (predicted) >80% and FEV1/FVC >80%
- Mild persistent: Symptoms >2 d/wk, but not daily, nighttime awakenings 3–4×/month, short-acting β-agonist use >2 d/wk, but not daily, minor limitations in normal activity, and FEV1 (predicted) >80% and FEV1/FVC >80%
- Moderate persistent: Daily symptoms, nighttime awakenings ≥1×/wk but not nightly, daily use of short-acting β-agonist, some limitation in normal activity, and FEV1 (predicted) 60–80% and FEV1/FVC 75–80%
- Severe persistent: Symptoms throughout the day, nighttime awakenings often 7×/wk, short-acting β-agonist use several times a day, extremely limited normal activity, and FEV1 (predicted) <60% and FEV1/FVC <75%
- Affects 5–10% of population
- One of the most common chronic diseases of childhood, affecting 7 million children
- In children, more common in boys than girls
- In adults, more common in women than men, African Americans than Caucasians
In the US, maternal asthma complicates approximately 4–8% of all pregnancies.
Prevalence of asthma in seniors (>age 65) is 5.3%
- Host factors: Genetic predisposition, gender, race, BMI
- Environmental: Viral infections, animal and airborne allergens, tobacco smoke, etc.
- Exercise, obesity, and emotional stress
- Aspirin or NSAIDs hypersensitivity or β-blockers
- Food allergies and asthma → increased risk for fatal anaphylaxis from those foods.
- Inheritable component with complex genetics and environment interaction
- A gene-by-environment interaction occurs in which the susceptible host is exposed to environmental factors that are capable of generating IgE, and sensitization occurs.
- Eliminate or modify exposure to asthma triggers (e.g., allergens, smoking, aspirin, NSAIDs)
- Consider allergen immunotherapy.
- Treat comorbidities such as allergic rhinitis.
- Annual influenza vaccine (inactivated influenza vaccine) for age <6 months
- Patients at risk for anaphylaxis should carry an EpiPen.
- Airway inflammation begins with inflammatory cell infiltration, sub-basement fibrosis, mucus hypersecretion, epithelial injury, smooth muscle hypertrophy, angiogenesis that then leads to intermittent airflow obstruction and bronchial hyperresponsiveness
- Remodeling of airways may occur (1).
Commonly Associated Conditions
- Atopy: Eczema, allergic conjunctivitis, allergic rhinitis
- Obesity (associated with higher asthma rates)
- Gastroesophageal reflux disease (GERD)
- Obstructive sleep apnea (OSA)
- Allergic bronchopulmonary aspergillosis (rare)