Asthma

Reviewed by Dr Gavin Petrie, consultant respiratory physician and Dr Paul Klenerman, consultant physician

What is asthma?

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 (bronchi).

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 which 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) which 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.

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 irritant 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.

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