What is Asthma?
- Asthma is a common heterogeneous chronic disorder of the airways, characterized by variable usually reversible and recurring symptoms related to one or more of airflow obstruction, bronchial hyper-responsiveness, and underlying inflammation.
Symptoms of Asthma
- Tightening of air passage
- Thick mucus
- Difficulty in breathing
- Respiratory distress
- Wheezing
- Coughing
- Tightness of the chest
Pathophysiology
Asthma is an inflammatory disease and not simply a result of excessive smooth muscle contraction.
- Increased airway inflammation follows exposure to induders such as allergens or viruses, exercise, or inhalation of nonspecific irritants.
- Increased inflammation leads to exacerbations characterized by dyspnea, wheezing, cough, and chest tightness.
- Abnormal histopathology including edema, epithelial cell desquamation, and inflammatory cell infiltration.
Phases of Asthma
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Early phase (Acute):
- Due to bronchial smooth muscle spasm & excessive secretion of mucus.
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Chronic phase:
- Continuous inflammation, fibrosis, edema, necrosis of bronchial epithelial cells.
Box 1: Pathophysiology of Asthma
Normal vs Asthma
A. Normal
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Muscle of bronchi are relaxed, allowing easy airflow.
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Normal bronchial tube
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Muscles of bronchi are tight and thickened.
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The bronchi are inflamed and filled with mucus, which impedes airflow.
-
Inflamed bronchial tube
Types of Asthma
- Allergic asthma (extrinsic)
- Non-allergic asthma (intrinsic)
- Cough variant asthma
- Occupational asthma
- Exercise-induced asthma
- Medication-induced asthma
- Nocturnal asthma
Triggers
- Allergies
- Tobacco smoke
- Environmental factors
- Obesity
- Pregnancy
- Stress
- Genes
- Atopy
Asthma Triggers
- Pets
- Exercise
- Pollen
- Bugs in the home
- Chemical fumes
- Cold air
- Fungus spores
- Dust
- Smoke
- Strong odors
- Pollution
- Anger
- Stress
Drugs Causing Bronchial Asthma
- Aspirin or nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity, sulfite sensitivity
- Use of beta-adrenergic receptor blockers (including ophthalmic preparations)
- Oral contraceptive pill
- Cholinergic agents
- Prostaglandin F₂