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What is it?
Asthma is a common condition that affects the Bronchi and bronchioles tubes that carry air in and out of the lungs. They are only millimetres wide and made up of ring-shaped muscles that can contract or relax. When a person with asthma comes into contact with something that irritates their airways the lining becomes inflamed and starts to swell. This also gives rise to the characteristic wheezy noise. Sometimes sticky mucus or phlegm builds up, causing further narrowing.
What are the causes?
It is difficult to say for sure what causes asthma but there are known contributory factors, including:
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Family history of asthma, eczema or allergies
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Smoking during pregnancy significantly increases the risk of the child developing asthma
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Children whose parents smoke are more likely to develop asthma
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Environmental pollution can make symptoms worse and may play a part in causing some asthma cases
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Adult onset asthma may develop after a viral infection
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Irritants found in the workplace may lead to a person developing asthma
Asthma is triggered by external agents, such as irritants in the air which are breathed in, such as pollen, dust, mould and animal fur, or by internal reactions in the body that have been caused by external influences such as exertion, cold, smoke, scents and pollution.
To acquire asthma people seem to need to have been born with a disposition to it, which may not reveal itself until they have been exposed to an irritant. Lack of exposure to infection in early life, certain drugs, low birthweight and well insulated houses leading to a higher concentration of dust mites may also be part of the problem.
What are the signs and symptoms?
The usual symptoms are coughing, wheezing, shortness of breath and tightness in the chest. Not everyone will get all of these symptoms. Some people may experience them from time to time and a few may experience them all the time.
How is it diagnosed?
The diagnosis is made on the basis of the patient’s history of symptoms and on simple tests of the lungs’ function. A peak flow meter which measures the speed and force with which air can be blown out of the lungs is commonly used and sometimes a test called spirometry may be done to confirm the diagnosis.
For those whose asthma is associated with eczema and hay fever, blood tests and skin sensitivity tests may be undertaken to look for hypersensitivity towards specific substances.
How is it treated?
Medicines for asthma are generally in two main groups – relievers (bronchodilators) and preventers (anti-inflammatories) – which are usually used in combination.
Relievers are fast-acting and relax the muscles of the airways and reduce swelling, which opens them up and makes it easier to breathe. There are three groups of these:
Beta-2 agonists which are used when required to relieve shortness of breath and stimulate the muscle to relax. They are inhaled from a variety of devices, the most familiar being the measured-dose inhaler, such as Ventolin.
Anticholinergics block the nerve impulses which control the muscles, allowing them to stay open. As the effect of this is fairly small it is usually used when the airways have been narrowed by other conditions, such as chronic bronchitis.
Theophyllines are given by mouth and are not widely used in this country because of side effects. They are in wide use throughout the rest of the world.
Preventers act over a longer time and reduce inflammation within the airways. They should be used regularly and when the dosage is correct there may be little need for preventers. There are three groups of these:
Corticosteroids reduce inflammation in the airways reducing their tendency to contract and have allowed many patients with previously troublesome asthma to lead almost symptom-free lives. They are usually given as an inhaler but sometimes oral steroid tablets may be required for severe attacks.
Cromones also reduce inflammation in the airways and are best given for mild asthma. They are more affective in children than adults.
Leukotriene receptor antagonists prevent the production of excess mucus as well as inflammation and narrowing of the airways. This is useful in treating asthma triggered by exercise and they are taken as tablets, but are effective only in a minority of patients.
Combination inhalers with a long-acting combination of bronchodilators and/or corticosteroids have been the mainstay of asthma treatment for a number of years. Patients seem to prefer them as treatment involves one inhaler and not two or three, so can be easier to manage. Familiar names include Seretide, Symbicort and Combivent UDVs.
Is there anything I can do to prevent it?
Yes, where possible by avoiding recognizable precipitants, such as dusts, smoke, infections and taking care with exercise. It can usually be well treated so that the symptoms give little trouble. Half of all children who develop asthma will grow out of it and for many adults asthma is variable with some good spells and some that aren’t so good. Some people are worse in the winter months and others in the summer hay fever season. Smoking can cause long term lung damage which will reduce lung function still further so it is vital to stop smoking.
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