Dr Shashank Jain
Bronchial asthma.
What is Asthma?
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A chronic obstructive disorder of the airways characterized by airway hypersensitivity to a variety of stimuli, resulting in transient bronchospasm and constriction of the airways. |
What happens during Asthma?
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Asthma is a condition involving lungs, marked by repeated attacks of shortness of breath, breathing difficulty, wheezing, coughing, and thick mucus coming from the lungs. |
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These attacks occur when the airways contract, swell, and clog up with mucus. |
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An attack may last a few minutes or a few hours. |
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The episodes may be started by breathing foreign substances (allergens) or pollutants, infection, vigorous exercise, or emotional stress. |
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In mild cases the attacks occur only occasionally, but people with severe asthma may have several attacks in a week (or even in a single day). |
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Although it's a chronic disease, people with asthma can learn how to manage these attacks and lead normal, active lives. |
What causes asthma?
There are two types of asthma:
Atopic (extrinsic) asthma and
Non Atopic (intrinsic) asthma.
Atopic (extrinsic) asthma
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The term Atopic, which means external, gives a clue to the cause of this type of asthma. Atopic asthma is a type of allergic reaction. Many people with Atopic asthma have other allergies, and there is often a family history of allergies. Common causes are dust, pollen, mold spores, insecticides, animals, and certain food. Atopic asthma usually, but not always, begins in childhood. |
Non Atopic (intrinsic) asthma.
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Non Atopic asthma typically begins after age 35, and the attacks are more frequent as time goes by. The cause is unknown, but it is believed to be an over-response of the immune system. Attacks are sometimes triggered by viruses (such as the common cold), exercise, emotional stress, or exposure to cold air, dust, or fumes. |
Allergic asthma ,also called extrinsic asthma.
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A form of asthma caused by breathing in an airborne substance. This allergen causes antibodies to form in the cells of the lung sacs. Histamine is then released, which causes the bronchial muscles to contract. This causes the coughing and wheezing of asthma. Mental factors may cause asthma attacks in patients whose bronchi are already infected with allergic material. Treatments are more effective for pollen sensitivity than for house dust, animal hair, molds, and insects. Often, a daily pattern of histamine release is seen, causing many degrees of attacks at different times of the day. |
How is asthma diagnosed?
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The diagnosis is done mainly with good history taken from patients about symptoms and doing a thorough clinical examination. |
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Unfortunately, no single test can diagnose asthma, and several tests must be performed. |
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Lung function tests involve breathing into a special machine to evaluate breathing performance. |
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Blood tests are made, which often include checking the amount of oxygen in the blood. This is done by drawing a small amount of blood from an artery. |
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Sputum is examined under the microscope, and a chest x-ray is made. |
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Skin tests are usually performed (if they have not been in the past) to identify allergies to common foods or other substances. |
How is asthma treated?
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Bronco-dilators are prescribed to relax the airways, and are the main type of medication used for treating asthma. |
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Aerosol inhalers are preferred over oral drugs because they act faster to relieve symptoms. |
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When asthma is severe, corticosteroids (oral or aerosols) are prescribed to suppress the body's reaction. Because steroids can have serious side effects, these drugs usually are prescribed orally, only for a short period of time. |
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However, inhalation steroids can be given for long durations of time whenever required, without any side effects. |
How can attacks be avoided?
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People who have asthma are wise to learn what triggers an attack and to avoid that item or situation. It is important to take medication regularly, as advised by doctor, even if there are no symptoms. |
Causes and Incidence
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Asthma is triggered by either extrinsic or intrinsic agents. |
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Extrinsic agents include allergens such as dust, smoke, pet dander, mold spores, chemicals, and foods. |
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Intrinsic agents include underlying respiratory infections, emotional stress, and fatigue. |
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Many attacks are triggered by a combination of agents. |
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It is the most common chronic disease of children and adults, starting in childhood about half the time and in adolescence or adulthood half the time. |
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In children, boys are affected twice as often as girls, but this ratio evens out by adolescence. |
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The prevalence and mortality rate are increasing worldwide; prevalence rose about 30% from 1980 to 1990. |
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Incidence in Delhi is increasing at all age groups and in both the sexes due to increasing pollution levels. |
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Various agents trigger a reaction in the tracheal and bronchial linings, which causes bronchospasm of the smooth muscle and constricts the airways. |
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The airways become inflamed and edematous (collection of fluid) and produce excess thickened secretions, which aggravate the blockage. |
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Eosinophils (allergic inflammatory cells) infiltrate the airway walls, injuring and desquamating the epithelial lining. Expiratory capacity is reduced, causing trapping of gas in the airways, hyperinflation, and labored breathing. |
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Because the obstruction is not uniform, blood flow continues in some areas of hypoventilation, producing a ventilation-perfusion imbalance and resulting in arterial hypoxemia (decreased blood oxygen concentration). |