Asthma is a common lung condition which narrows the airways and causes occasional breathing difficulties including wheezing, coughing and shortness of breath. It often starts in childhood, although it can also develop for the first time in adults.
There is currently no cure for asthma, but there are treatments that can help keep your symptoms under control. Family GP Dr Roger Henderson looks at the symptoms, risk factors and treatment options for asthma:
What is asthma?
Asthma is a chronic disease in which sufferers have repeated attacks of difficulty in breathing. It can develop at any age but most commonly begins in childhood, with at least 1 in 10 children and 1 in 20 adults having the condition.
Asthma can run in families but there may also be no other family members with it. 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.
What does asthma feel like?
✔️ If you have asthma it may be difficult to breathe, with a feeling of tightness in the chest and shortness of breath, along with wheezing (a fine whistling sound) when breathing out.
✔️ Coughing occurs - especially at night - and there may be increased production of mucus or phlegm.
✔️ Symptoms vary from person to person and from attack to attack. In some they are mild and occasional while others have continuous or severe breathing problems.
What is an asthma attack?
In recent decades there has been an increase in the number of people affected by asthma all over the world, especially in children. In 2017 (the most recent data available), every 10 seconds one person in the UK has a potentially fatal asthma attack and 3 people die every day from an asthma attack. Around 200,000 people in the UK have severe asthma that doesn’t respond to normal treatment.
How your lungs work
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.
How asthma affects your 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 ongoing chronic problem which is intermittently made worse during acute asthma attacks.
💡 About 5.4 million people in the UK are currently receiving treatment for asthma (approximately 1.1 million children and 4.3 million adults), costing the NHS £1 billion per year.
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.
The types of asthma
Asthma can be divided into two types:
• Allergic or extrinsic asthma
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 attack. 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.
• Non-allergic asthma
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 such as 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. Most people with asthma are susceptible to either of these types.
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 triggers an acute asthma attack?
A number of factors can trigger an asthma attack, including the following:
- Exertion and exercise.
- Cold air.
- Emotional stress.
- Air pollution including exposure to certain chemicals (an example is isocynates, 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 are the warning signs of a worsening asthma attack?
The signs that your asthma attack may be developing into something more serious may include the following. If you experience any of these symptoms, seek urgent medical assistance:
- Symptoms become more severe.
- Inhaled medicines appears less effective than usual, and you may realise you are taking more of your reliever inhaler.
- Worsening cough or wheeze on exertion.
- Night-time waking 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).
- Difficulty in talking.
- When it appears that your asthma is becoming less well controlled, you should consult your doctor straight away for advice on what to do.
- 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 for 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.
Asthma attack self-help treatment tips
There are a few things you can do to minimise symptoms of an asthma attack:
✔️ 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, 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.
✔️ Make sure you have an adequate supply of your treatments, and don't risk running out if symptoms get worse.
How does the doctor diagnose asthma?
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 with asthma?
It's important to keep 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 long term health prospects for asthma sufferers?
Although asthma cannot be cured it can usually be well treated so that the symptoms give little trouble. Around half of the children who get asthma 'grow out of it' with their asthma settling as they become adults.
It is vital to stop smoking to avoid developing long-term lung damage (COPD), which severely reduces lung function.
Severe attacks of asthma can be fatal but only if they are treated inadequately or not soon enough.
Medicine for asthma
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 or ease symptoms and can be used by themselves if you only have symptoms now and then. However, if you are using them more than 3 times a week to ease asthma symptoms then a preventer inhaler should also be used.
• 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.
A number of other types of drugs may also be used, for example to reduce secretions.
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) 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
These 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.
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 these nerve impulses, 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 drug is ipratropium bromide (eg Atrovent).
It has a maximum effect 30 to 60 minutes after inhalation, which lasts for three to six hours.
A longer lasting anticholinergic called tiotropium bromide need only be taken once a day and may sometimes be used in severe or chronic asthma but is slow in onset and so not for acute attacks.
All three types of reliever can be combined if necessary.
There are some drugs that can be used as asthma preventers:
Corticosteroids (or steroids) such as beclomethasone, budesonide and fluticasone have made a big impact on the management of asthma.
They work to reduce the amount of inflammation within the airways, reducing their tendency to narrow down 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 may be required as part of the treatment of severe attacks (rather than for prevention).
Although steroids are powerful medicines with many potential side effects, their effectiveness 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 asthma is well treated.
• Leukotriene receptor antagonists
Leukotrienes are chemicals that 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.
The most commonly used leukotriene receptor antagonist is montelukast (Singulair) which is taken as a tablet.
A new 'biological therapy' has recently been introduced for severe persistent allergic asthma called Omalizumab (Xolair). This is a recombinant monoclonal antibody that prevents the release of the chemicals involved in inflammation and reduces allergen-induced airway reactions. However, this treatment is only currently used in very specific cases in people with severe persistent allergic asthma that is not controlled with over treatments. It is given by injection and can only be started by a specialist.
• Combination inhalers
Combination inhalers have been the mainstay of asthma treatment for a number of years. In the 1990s longer-acting treatments which combined bronchodilators and corticosteroids and delivered them together using just one device were developed.
There are currently a number of these regularly used in the UK, and many patients feel their asthma is much better controlled on these combination inhalers and so are more likely to use them effectively 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.