Allergic asthma
Common Allergens in Allergic
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Pollens from grass, weeds, and trees
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Mold spores and mold fragments
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Animal danders (hair, skin and feathers) and saliva
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Dust mite feces
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Cockroach feces
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Food allergens: food preservatives like potassium bisulphate and sodium benzoate.
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Other food allergens are egg, milk, peanut, sesame and others.
Other triggering agents in asthma
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Smokes from fire place, candles, fireworks, and incense sticks.
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Tobacco smoke
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Air pollution
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Cold air
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Strong chemical odors and perfumes
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Dusty work places
Pathology in allergic asthma
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Following exposure to allergens, allergic reaction sets up in airways.
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There is a complex interaction btw mast cells, IgE, esinophils, T- lymphocytes, macrophages and dendritic cells.
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These cells release many mediators like Leukotriene C4, interferons and cytokines.
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These mediators cause constriction and spasm of bronchial airways, edema of bronchial walls and mucus plugging the airways.
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Long term changes in airways referred to as airway modeling, can lead to fibrosis and irreversible airway obstruction in some of the patients.CC
Clinical signs and symptoms
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Cough with expectoration
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Wheezing
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Shortness of breathe
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Chest pain and tightening
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Rapid breathing
Severity of asthma
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Intermittent |
Mild persistent |
Moderate persistent |
Severe persistent |
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Day time symptoms |
Daytime symptoms 2 or fewer times/week |
Daytime symptoms >2 per week. but not daily |
Daily symptoms |
Symptoms through the day |
|
Night time awakening |
Night time awakenings 2 or fewer times/month |
Night time awakenings 3-4 times per month |
More than 1/week |
7 times/week |
|
Use of beta agonist |
2 or fewer times/month |
>2 times per month, but not daily |
Daily use |
Several times per day |
|
Interference in normal activity |
None |
Minor limitation |
Some limitation |
Extremely limited |
|
Lung function tests |
FEV1 >80% FEV1/FVC ratio normal |
FEV1 >80% FEV1/FVC ratio normal |
FEV1 >60% but <80% predicted, FEV1/FVC ratio reduced 5% |
FEV1 <60% predicted, FEV1/FVC ratio reduced more than 5% |
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Exacerbations requiring of systemic corticosteroids |
One per year at most |
2 or more exacerbations per year |
2 or more exacerbation per year |
2 or more exacerbations per year |
|
Recommended therapy |
Step 1- Short acting beta agonists |
Step 2- Low dose steroid inhalers, or Cromolyn, Leukotriene inhibitors, Theophylline |
Step 3- Low dose oral corticosteroids + low-dose inhaled corticosteroids + long-acting beta-agonist |
Step 4- Low dose oral corticosteroids + low-dose inhaled corticosteroids + long-acting beta-agonist+ Leukotriene receptor antagonist, Theophylline, or zileuton. To consider anti-IgE therapy Omalizumab in allergic patients. |
To consider allergic immunotherapy in allergic patients
Tests and diagnosis
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Serum IgE levels
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Absolute esinophils
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Sputum examination
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Chest radiography
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Chest CT scan
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Echocardiogram
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Pulmonary function test
Treatment
Pharmacotherapy
Corticosteroids
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Inhaled steroids: Budesenoid, Fluticasone, Flunisolide, Betamethasone)
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Systemic steroids: Prednisolone, Hydrocortisone, and Methyl prednisolone.
Bronchodilators
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Short acting beta agonists: Salbutamol, Albuterol
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Long acting beta agonists: Salmetrol, Formoterol
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Methyl Xanthine: Theophylline, Deriphylline
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Anticholinergics: Ipratropium and Tiotropium bromide
Leukotriene-modifying agents
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Zakirlukast, Motelukast, and Zileuton
Mast cell stabilizing agents
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Sodium chromoglycate, Nedocromil and Ketotinfen
Monoclonal antibodies
Omalizumab
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DNA derived human IgG monoclonal antibody that binds selectively to human IgE receptor on surface of mast cells and basophils.
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It down regulates the mediators of allergic response in asthma.
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Indicated in moderate to severe persistent asthma.
Environmental control
Allergen avoidance- A multifaceted approach is necessary, as individual interventions are rarely successful.
Allergen immunotherapy
Allergen immunotherapy should be considered in those the specific allergens have a proven relationship to symptoms.
