What is asthma?
| Make sure you use the right technique when you take your asthma medication. Poor technique is the most common reason for ineffective treatment. |
Asthma is a chronic disease in which sufferers have repeated attacks of difficulty in breathing and coughing. There seems to be an increase in the amount of asthma all over the world, especially in children. To understand what happens in asthmatic attacks it is helpful to visualise the basic structure of the airway tubes of the lung.
The main airway (windpipe, trachea) of the body is about 2-3cm across. It divides into its main branches (bronchi), which lead to the right and left lung, which divide further, like the branches of a tree, to supply air to all parts of the lungs.
The smallest tubes (bronchioles) are only millimetres wide and they are made up of ring-shaped muscles that are capable of contracting or relaxing. Anything that makes them contract will narrow the passages, which makes it more difficult for the air to pass through and also gives rise to the characteristic wheezy noise.
Asthmatics tend to be sensitive to various types of irritants in the atmosphere that can trigger this contraction response from the bronchial muscles.
The bronchi also have an inner lining that becomes inflamed in asthma, which makes the lining swell and produce an excess amount of the mucus (phlegm) it normally makes.
All of these processes contribute to the airway narrowing and the treatment for asthma is aimed at reversing them as much as possible.
People of all ages get asthma but 50 per cent of sufferers are children, mostly boys, under 10. Among adults, women are more likely to develop asthma than men. Over 5 million people in the UK are currently receiving treatment for asthma , with it costing the NHS £1,000 million per year (stats from Asthma UK)
How do you get asthma?
Asthma can be triggered by external agents, such as irritants in the atmosphere which are breathed in, or by internal reactions within the body that have been caused by an external influence. The kinds of provoking factors can be divided into two groups:
non-specific factors: all asthma patients are affected by a number of things that are referred to as irritants. They include exertion, cold, smoke, scents and pollution.
specific factors: these are irritants or allergens in the form of pollen, dust, animal fur, mould and some kinds of food. A virus or bacteria, chemical fumes or other substances at the workplace and certain medicines, eg aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), may also cause asthma.
To acquire asthma, people seem to need to have been born with a predisposition to the disease. It may not reveal itself until they have been exposed to some asthma irritants.
Smoking mothers, low birth weight, a lack of exposure to infection in early life and traffic fumes have all been associated with the increase in asthma. Less draughty houses resulting in a higher concentration of house dust mites and cooking gases may also be part of the problem.
Currently, a great deal of research looking for the genes that allow asthma to develop is being carried out. But until we can prevent asthma, we have to suppress the symptoms and try to avoid the triggers where possible.
What might trigger acute asthma attacks?
Exertion.
Cold.
Smoke.
Air pollution including exposure to certain chemicals. An example is isocynates which are used in some painting and plastics industries.
Airway infection.
Allergies, eg to pollens, house dust mites, domestic animals (especially cats), aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.
What does asthma feel like?
It is difficult to breathe and there is shortness of breath.
Wheezing when breathing out.Coughing, especially at night and with a little mucus.
What are the warning signals of worsening attacks?
Inhaled medicines appears less effective than usual.
Symptoms of cough or wheeze on exertion.
Night-time wakening with wheeze or cough.
Fall in the peak flow meter reading (a peak flow meter is a simple device that measures the maximum speed at which a person can breathe out).
When it appears that your asthma is becoming less well controlled, you should consult your doctor for advice on what to do.
What are the danger signals of severe attacks requiring immediate medical attention?
Bluish skin colour and gasping breath.
Exhaustion so severe that speech is difficult or impossible.
Confusion and restlessness.
What can you do to help yourself?
Avoid the substances you are allergic to, if possible. It can be difficult to know which specific factors may give you trouble, but general irritants like tobacco smoke should be avoided.
It is important to take your prescribed preventive medicines, even if you feel well.
If you get a serious attack, contact your doctor or the emergency services.
Discuss your treatment with your doctor or practice nurse. You should know what to do if, for example, you get a bit worse during a cold. This will usually involve a temporary increase in the dosage of your treatment.
Be familiar with the use of a peak flow meter, which can help you judge your asthma during spells when it is worse.
Make sure you use your inhaler device correctly. If you are unsure your practice nurse, doctor or pharmacist will be able to help and advise you.
How does the doctor make the diagnosis?
The diagnosis is made on the basis of the patient's history of symptoms and on simple tests of the lungs' function but it is not always easy to come to a diagnosis of asthma if the symptoms are mild and intermittent.
For those people whose asthma is associated with eczema and hay fever it can be helpful to take blood samples and skin tests to look for hypersensitivity towards specific substances.
What should I do?
Be active. If you get attacks during intense activity it may be a good idea to take 'reliever' medicine before you begin to exercise. These medicines, properly known as bronchodilators, have a relaxing effect on the muscle surrounding the bronchioles. Swimming is probably the best form of exercise for asthma patients but the most important thing is to stay active.
What are the prospects for asthma suffers?
Although asthma cannot be cured it can usually be well treated so that the symptoms give little trouble.
Half of the children who get asthma 'grow out of it'.
It is vital to stop smoking to avoid developing long-term lung damage (chronic bronchitis, 'smoker's lung'), which will reduce the lung function drastically.
Severe attacks of asthma can be fatal but only if they are treated inadequately or not soon enough.
Medicine
Medicines for asthma are generally thought of in two main groups.
Relievers (bronchodilators): these are quick-acting medicines that relax the muscles of the airways. This opens the airways and makes it easier to breathe. They are used to relieve symptoms.
Preventers (anti-inflammatories): these act over a longer time and work by reducing the inflammation within the airways. They should be used regularly for maximum benefit. When the dosage and type of preventive medicine is correct, there will be little need for reliever medicines.
Relievers
There are three groups of these.
Beta-2 agonists
Beta-2 agonists act on molecule-sized receptors on the muscle of the bronchioles. The medicine fits the receptor like a key fits a lock and causes the muscle to relax. Examples of those which act for a short time (three or four hours following a single dose) are salbutamol (eg Ventolin) and terbutaline (eg Bricanyl). These start to work very quickly after inhalation and are used when required to relieve shortness of breath. They can also be used to open the airways before exercise.
Longer-acting beta-2 agonists include salmeterol (Serevent) and formoterol (eg Foradil, Oxis). Their action lasts over 12 hours, making them suitable for twice-daily dosage to keep the airways open throughout the day.
Formoterol works rapidly to open the airways like the short-acting beta-2 agonists. A combination inhaler called Symbicort, which contains formoterol together with the corticosteroid budesonide, is licensed to be used regularly as a preventer and when needed as a reliever to relieve shortness of breath. Symbicort is only licensed for use as both preventer and reliever in adults over 18 years of age.
Beta-2 agonists are inhaled from a variety of delivery devices, the most familiar being the pressurised metered-dose inhaler (MDI). Other devices include breath-actuated inhalers such as autohalers and dry powder inhalers such as turbohalers.
Anticholinergics
One of the ways in which the size of the airways is naturally controlled is through nerves that connect to the muscles. The nerve impulses cause the muscles to contract, thus narrowing the airway. Anticholinergic medicines block this effect, allowing the airways to open. The size of this effect is fairly small, so it is most noticeable if the airways have already been narrowed by other conditions, such as chronic bronchitis. An example of an anticholinergic isipratropium bromide (eg Atrovent). It has a maximum effect 30 to 60 minutes after inhalation, which lasts for three to six hours.
Theophyllines
Theophylline (eg Slo-phyllin) and aminophylline (eg Phyllocontin continus) are given by mouth and are less commonly used in Britain because they are more likely to produce side effects than inhaled treatment. They are still in very wide use throughout the world.
All three types of reliever can be combined if necessary.
Preventers
There are three main groups of these.
Corticosteroids
Corticosteroids (or 'steroids') such as beclometasone (eg Beclazone), budesonide (eg Pulmicort) and fluticasone (eg Flixotide) have made an enormous difference to the management of asthma. They work to reduce the amount of inflammation within 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 inhaled treatment, although sometimes oral steroid tablets (prednisolone, eg Deltacortril) may be required for severe attacks.
Although steroids are powerful medicines with many potential side effects, their safety in asthma has been well established. It is also important to balance the problems that arise from poorly treated asthma against the improvement in health which occurs when the condition is well treated.
Cromones
There are two medicines in the cromone group: sodium cromoglicate (eg Intal) and nedocromil sodium (Tilade).
They also act to reduce inflammation of the airways. They tend to be best for mild asthma and are more effective in children than adults. The medicines are given by inhalation and are usually very well tolerated.
Leukotriene receptor antagonists
Leukotrienes are released from the lungs in people with asthma, causing inflammation and increased mucus production in the airways. They also cause the muscles lining the airways to contract, which narrows the airways. All of this makes it difficult for air to get in and out of the lungs.
Leukotriene receptor antagonists block leukotriene receptors in the lungs and, as a result, block the action of the leukotrienes. This prevents the excess mucus production, inflammation and narrowing of the airways and so prevents asthma attacks. It’s also useful for preventing asthma triggered by exercise.
By blocking this effect with these antagonist medicines the constriction is reversed. There are two leukotriene receptor antagonists currently available: montelukast (Singulair) and zafirlukast (Accolate), both of which are taken as tablets.
Combination inhalers
Combination inhalers have been the mainstay of asthma treatment for a number of years.
In the 1990s longer-acting combinations of bronchodilators and/or corticosteroids in one apparatus were developed. There are currently a number of these regularly used in the UK, such as Seretide (salmeterol, fluticasone),Symbicort (budesonide, formoterol) and Combivent UDVs (salbutamol, ipratropium).
Many patients feel their asthma is much better controlled on these combination inhalers and compliance is much better as they only need to use one inhaler rather than two.
Easy to use, they can also be useful in visually impaired patients and those who find using two or even three inhalers difficult to remember.
Some trials have found that morning peak flow rates are better using combination inhalers rather than single inhaler alone.
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