What is asthma?
In recent decades there has been an increase in the number of people affected by asthma all over the world, especially in children.
However, since the 1990s the percentage of the population who are affected seems to have levelled out in the UK at least.
To understand what happens in an asthmatic attack, it's helpful to visualise the basic structure of the airway tubes of the lung.
The main airway (windpipe, trachea) of the body is about 2 to 3cm across. It divides into its main branches (bronchi), which lead to the right and left lung. Each bronchus divides 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 (so making it harder to breathe) and also gives rise to the characteristic wheezy noise that a person makes when they have an asthma attack.
Asthmatics tend to be sensitive to various types of irritants in the atmosphere that can trigger this contraction response from the bronchial muscles.
The bronchioles also have an inner lining that becomes inflamed in asthma. This inflammation makes the lining swell (further narrowing the airway) and produce an excess amount of the mucus (phlegm) it normally makes, clogging up the tubes.
All of these processes contribute to the airway narrowing and the treatment for asthma is aimed at reversing them as much as possible. The airway inflammation and narrowing may be an on-going chronic problem which is intermittently made worse during acute asthma attacks.
People of all ages get asthma but 20 per cent of sufferers are children. Asthma is slightly more common among boys than girls. But after puberty the pattern reverses and among adults, women are more likely to develop asthma than men.
About 5.4 million people in the UK are currently receiving treatment for asthma (about 1.1 million children and 4.3 million adults), with it costing the NHS £1,000 million per year (stats from asthma UK).
How do you get asthma?
In most cases a person who develops asthma has been born with an inherited predisposition to the disease.There may be a family history of asthma, and a great deal of research is being carried out to look for the genes that allow asthma to develop (some of these genes have been identified).
However environmental factors are important too, and asthma may not reveal itself until that person is exposed to a particular asthma trigger in their environment.
Some other links have been established.
A mother who smokes, a low birth weight, and exposure to traffic fumes have all been associated with asthma.
It's also thought that the modern obsession with a very clean environment in early life (avoiding exposure to infections and particularly parasites) may mean than a child's immune system is not 'primed' properly and an increased sensitivity to asthma triggers results.
Modern housing may also play a part, as less draughty, better heated homes result in higher levels of house dust mites or cooking gases.
Asthma can be dividied into two types.
- In allergic or extrinsic asthma, an attack is triggered by agents which cause an allergic reaction, for example when pollen, dust mites or animal fur are breathed in. Some kinds of food can also trigger an attacks. These agents are known as allergens – they consist of foreign proteins which activate the immune system. A reaction to animal fur is actually a reaction to a protein in the animals saliva which been coated onto the fur as the animal grooms itself.
- Asthma may also be triggered by non-allergic factors. This is known as intrinsic or non-allergic asthma and factors which cause an attack include anxiety, stress, exercise and cold air, as well as smoke, chemical fumes, and other irritants including viral infections. Certain medicines, eg aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), may also cause an asthma attack. Although these factors cause inflammation of the airways, they do not activate the immune system.
Until we can prevent asthma, the aim is to try to avoid these triggers where possible, and then effectively manage symptoms during an attack.
What might trigger an acute asthma attack?
- Exertion and exercise.
- Cold air.
- Smoke.
- Emotional stress.
- Air pollution including exposure to certain chemicals. An example is isocynates, which are used in some painting and plastics industries.
- Airway infection, eg viral infections such as colds.
- Chemical irritants including chemicals in medicines such as aspirin and non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.
- Allergies, eg to pollens, house dust mites, some foods, and the fur or dander from domestic animals (especially cats and horses). In these allergies, the immune system is reacting to a foreign protein or 'allergen'.
What does asthma feel like?
- It is difficult to breathe, with a feeling of tightness in the chest, and there is shortness of breath.
- Wheezing (a fine whistling sound) when breathing out.
- coughing, especially at night and there may be increased production of mucus or phelgm.
What are the warning signals of worsening attacks?
- Symptoms become more severe.
- Inhaled medicines appears less effective than usual, and you may realise you are taking more of your reliever inhaler.
- 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).
What are the danger signals of severe attacks requiring immediate medical attention?
- Severe shortness of breath, so that you can't complete a sentence.
- Having to sit hunched forwards to breathe.
- Bluish skin colour (especially noticeable around the lips or fingernails) and gasping breath.
- Exhaustion so severe that speech is difficult or impossible.
- Fast breathing but with a silent chest (ie the wheeze disappears – a sign that very little air is even moving in and out of the lungs).
- Confusion and restlessness.
- Drowsiness.
What can you do to help yourself?
- Avoid the substances you know that you are allergic to, or that you know tend to trigger an attack for you 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 ur treatment with ur docter 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 peak flow meter, which can help you judge your asthma during spells when it is worse.
- Make sure you use your inhaler correctly. If you are unsure your practice nurse, doctor or pharmacist will be able to help and advise you.
- Make sure you have an adequate supply of your treatments, and don’t risk running out if symptoms get worse.
How does the doctor make the diagnosis?
A diagnosis of asthma is made on the basis of a patient's history of symptoms combined with simple tests of how the lungs are functioning (this may include a peak flow test, which uses a simple device to measure how fast you can breathe air out of your lungs).Sometimes treatments such as reliever inhalers are tried, simply to see if they help symptoms (and therefore help establish the diagnosis). But it's 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 indicating an allergic aspect to their symptoms, it can be helpful to take blood samples and skin tests to look for hypersensitivity towards specific substances.
Can I safely exercise?
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 bronchodilter, 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 (bronchodilater): 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-inflamentries): 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 many different drugs used as asthma relievers, and they fall into three groups.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
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 (eg 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.Some combination inhalers contain both a long-acting beta-2 agonist to open the airways and a steroid drug to reduce inflammation (ie preventer drugs). These include Seretide (which contains salmeterol and fluticasone) and Symbicort (formoterol and budesonide).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.
No comments:
Post a Comment