Etiology of Asthma
What Causes Asthma Episodes?
The exact etiology or causes of asthma is still unknown. The airways of the asthmatics are found to be inflamed, red and hypersensitive. It is known that some triggers induce an asthma attack if exposed to the inflamed airways. Therefore, the management plan for asthma is directed towards prevention of inflammation of the airway and avoidance of triggers for the better control of symptoms.
What is a trigger?
Asthmatic people have airways that are highly sensitive to certain things which do not bother people without asthma. These things are called “triggers”. When an asthmatic comes in contact with them, an asthma episode starts. The airways become swollen, produce too much mucus, and are tightened up.
What are the triggers of asthma?
Common triggers of asthma can be classified as follows :
A. Allergens (Individual specific)
(i) Outdoor allergens
- Pollens - from grass & trees
- Molds - of some fungi
(ii) Indoor Allergens
- House dust mites
- Dander (or flakes) -from the skin, hair or feathers of warm - blooded pets (dogs, cats, birds, rodents, etc.)
- Molds -harboured in Vacuum cleaners, Air-con- ditioners, Humidifiers.
- Insects -Cockroach
(iii) Food Allergens
Rarely cause an asthma attack. Though some of foodstuffs may cause allergic manifestations in some people. it is not wise to band allergy producing foods in general for an asthmatic. Avoid those specific foods which evokes an asthma/allergy attack within few minutes or hours after intake. Commonly allergy-producing foods are:
- Beef, Prawn, Hilsha and some other fishes, sea-foods, duck egg, some vegetables, nuts, etc.
- Food additives, e.g. metabisulphite, tartrazine.
B. Irritants (More generalized)
(i) Tobacco smoke
(ii) Wood smoke
(iii) Strong odours, perfumes and sprays, cosmetics, paints, cooking (especially with spices)
(iv) Air-pollutants - Smoke and toxic gases from automobiles and factories.
C. Upper respiratory tract infection - viral infections, common cold
D. Exercise - strenuous physical activities.
E. Certain Drugs - e.g. b-blockers (even eye drops), Aspirin, NSAIDS etc.
F. Changes in season, weather and temperature- An asthma attack is likely if temperature lowers for 30C or more than the previous day.
G. Stress i. Emotion - e.g. Laughing, Sobbing, Mental depression
Is there a cure for asthma?
The word “cure” is difficult to apply in case of asthma. However, asthma can be controlled. We should expect nothing less. If a person uses anti-inflammatory preventive drugs for a long time, say for 2-5 years, then 60-80% cases of childhood asthma and 20-30% cases of adult asthma may go into complete remission. This complete remission may be induced spontaneously as well, sometimes going the credit to the “faith healers”.
What do we mean by remission?
It is a state in which a patient remains asymptomatic without any drug for at least one year or more. If remission persists throughout life, then we can say that patient is somewhat "cured". "Cure" is possible but still we can not predict who will go into that complete remission or "cure" and who will not.
How can asthma episodes be prevented?
To prevent asthma episodes the doctor should follow the golden rule of Asthma Association:
Education - Caution - Medication.
Emphasis should be given on the following points:
- Develop a profile of ingredients of an attack
- Identify and avoid triggers
- Identify the warning signs
- Take emergency steps when an attack is imminent
Can anti-allergy vaccines (immunotherapy) cure asthma?
No well controlled study in our country is available for the effectiveness of immunotherapy in the management of asthma. None is getting immunotherapy alone, rather taking along with reliever and preventer drugs. Though vaccines or immunotherapy for asthma can relieve symptoms upto a certain level in some patients, it is expensive, duration of treatment is usually 3 to 5 years in common, continuation for longer duration may be necessary and benefit is usually short lasting. Immunotherapy may be tried in managing allergen induced asthma when allergen avoidance is not adequate or possible.
For the treatment of bronchial asthma, immunotherapy is under trial and research is still going on. In future its helpful role, if any, in asthma management may be revealed. However we do not advocate vaccines for treatment of asthma yet. Immunotherapy is more indicated in management of Allergic Rhino conjunctivitis and Atopic Dermatitis.
- Asthma and Allergy Foundation of America: http://www.aafa.org/
- American Asthma Foundation: http://www.americanasthmafoundation.org/
- Asthma, UK: http://www.asthma.org.uk/all_about_asthma/index.html
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