ASTHMA BACKGROUNDER

What is asthma?

Asthma is a chronic, inflammatory condition of the airways - the inflammation causes the airways to be hyperactive, narrowing excessively or inappropriately in response to a wide range of stimuli. This narrowing is usually reversible but, eventually, the effects of long-term inflammation may lead to irreversible obstruction of airflow. Asthma is a common, but serious, disease.

Who is affected by asthma?

• One in 20 adults and 1 in 7 children, are affected at any one time
• A typical practice of 10,000 patients will have about 500 asthmatics
• About 2,000 deaths are caused by asthma annually in the UK, and this number is not falling. Most are thought to be preventable, as many patients are not being optimally managed

Asthma can begin at any age: the incidence is about five times greater in the first decade of life, with another slight peak in the thirties. Many children 'grow out' of it, but half of these will develop asthma again in later life.

What are the symptoms of asthma?

There are a number of symptoms which may indicate asthma:

• Cough - This may be the only symptom, particularly in young children
• Wheeze - Not seen in all asthmatics; most common in young adults and the middle-aged
• Chest Tightness - Most common in young adults and the middle-aged
• Breathlessness - May be the main/only symptom in elderly asthmatics

The symptoms of asthma can come and go rapidly and may vary from patient to patient. Sufferers may have:

• Occasional, well-defined attacks lasting hours or a few days
• Episodic attacks, but which last longer: days/weeks
• Continuous symptoms

What happens in an asthma attack?

In an asthma attack, there is excessive narrowing of the airways - bronchoconstriction - and the above symptoms are the direct effects of this restriction to airflow. Bronchoconstriction is due to a combination of events: Bronchospasm is the sharp contraction of bronchial muscle which not only narrows the airways but also distorts their epithelial lining and the underlying tissue (submucosa). With repeated bronchospasm, the muscle thickens so the airways become chronically narrowed.

This is then followed by Oedema resulting from blood capillaries dilating and leaking plasma, which causes localised swelling in the submucousal layer and further narrowing of the airways Epithelial Damage may also occur. When damaged epithelial cells slough off, exposing the basement membrane which thickens to protect the submucosa, mucus glands then produce excessive amounts of sticky, yellow mucus which clog the airways.

What can trigger an asthma attack?

Asthma attacks can be brought on by any one (or more) of a number of factors. They irritate the hyperactive bronchial tissues of asthmatics and trigger off the symptoms of bronchoconstriction. Common trigger factors are:
Environmental Irritants: house dust mite, smoke and fumes, pollen and spores, animal hair and dander, certain foods, medicines and drinks.
Occupational asthma can develop from exposure to a long list of industrial substances:
Air: specifically, sudden inhalation of cold or dry air and the rapid inspiration of air during exercise, laughter or hyperventilation
Intrinsic: e.g. respiratory infections, pregnancy and menstruation, emotion and stress.
There are number of ways by which an asthmatic can reduce their exposure to allergens that may trigger an attack:

• House dust mites live in bedding, carpets and soft furnishings. Although difficult to eradicate these completely, vacuuming and damp dusting regularly can help. The use of mattress and pillow covers can also help and avoiding feather and wool on bedding and pillows and by using synthetic instead.
• Stepping outside on a cold day can make asthmatics wheeze, so many take a dose of beta-agonist before going out.
• Many asthmatics are allergic to family pets, so it is best to avoid them whenever possible.