Understanding Asthma

Asthma is a common long-term condition that can cause coughing, wheezing, chest tightness and breathlessness.
The severity of these symptoms varies from person to person. Asthma can be controlled well in most people most of the time, although some people may have more persistent problems.
Occasionally, asthma symptoms can get gradually or suddenly worse. This is known as an "asthma attack", although doctors sometimes use the term "exacerbation".

Symptoms of asthma

The symptoms of asthma can range from mild to severe. Most people will only experience occasional symptoms, although a few people will have problems most of the time.

The main symptoms of asthma are:

• wheezing (a whistling sound when you breathe)
  shortness of breath
  a tight chest – which may feel like a band is tightening around it
  coughing

These symptoms are often worse at night and early in the morning, particularly if the condition is not well controlled. They may also develop or become worse in response to a certain trigger, such as exercise or exposure to an allergen.

Causes of asthma

It's not clear exactly what causes asthma, although it is likely to be a combination of factors.
Some of these may be genetic. However, a number of environmental factors are thought to play a role in the development of asthma. These include air pollution, chlorine in swimming pools and modern hygiene standards (known as the "hygiene hypothesis").
There is currently not enough evidence to be certain whether any of these can cause asthma, although a variety of environmental irritants, such as dust, cold air and smoke, may make it worse.

Who is at risk?

Although the cause of asthma is unknown, a number of things that can increase your chances of developing the condition have been identified. These include:
-a family history of asthma or other related allergic conditions (known as atopic conditions) such as eczema, food allergy or hay fever
-having another atopic condition
-having bronchiolitis (a common childhood lung infection) as a child
-childhood exposure to tobacco smoke, particularly if your mother also smoked during pregnancy
-being born prematurely, especially if you needed a ventilator to support your breathing after birth
-having a low birth weight as a result of restricted growth within the womb

Some people may also be at risk of developing asthma through their job.

Asthma triggers
In people with asthma, the small tubes (bronchi) that carry air in and out of the lungs become inflamed and more sensitive than normal.

This means that when you come into contact with something that irritates your lungs (a trigger), your airways become narrow, the muscles around them tighten, and there is an increase in the production of sticky mucus (phlegm).
Asthma symptoms can have a range of triggers, such as:

-respiratory tract infections – particularly infections affecting the upper airways, such as colds and the flu
-allergens – including pollen, dust mites, animal fur or feathers
-airborne irritants – including cigarette smoke, chemical fumes and atmospheric pollution
-medicines – particularly the class of painkillers called non-steroidal anti-inflammatory drugs (NSAIDs), which includes aspirin and ibuprofen, and beta-blockers sometimes given for high blood pressure or some types of heart disease
-emotions – including stress or laughing
-foods containing sulphites – naturally occurring substances found in some food and drinks, such as concentrated fruit juice, jam, prawns and many processed or pre-cooked meals
-weather conditions – including a sudden change in temperature, cold air, windy days, thunderstorms, poor air quality and hot, humid days
-indoor conditions – including mould or damp, house dust mites and chemicals in carpets and flooring materials
exercise
-food allergies – including allergies to nuts or other food items

Once you know your asthma triggers, you may be able to help control your condition by trying to avoid them.

Inhalers

Asthma medicines are usually given by inhalers – devices that deliver medication directly into the lungs as you breathe in.
This is an effective way of taking an asthma medicine as most goes straight to the lungs, with very little ending up elsewhere in the body.
Each inhaler works in a slightly different way. You should have training from your GP or nurse in how to use your device or how to help your child use theirs. This should be checked at least once a year.
Some inhalers are pressurised canisters – similar to a spray deodorant or an air freshener. You press the inhaler while breathing in, so the vapour containing the medication can pass into your lungs.
Some inhalers are not pressurised canisters but contain the medication in dry powder form, usually in a capsule that is punctured when the inhaler is "primed".
It is not possible to use a spacer with these inhalers and, unlike pressurised canisters, the powder must be inhaled quickly and forcefully if the medication is to reach the lungs.

Spacers

Pressurised canister inhalers can work better if given through a spacer – a hollow plastic or metal container with a mouthpiece at one end and a hole for the inhaler at the other.
Children under the age of three may have a spacer attached to a face mask rather than a mouthpiece, as this can make it easier for them to breathe in the medicine.
When using a spacer, the vapour from the inhaler is released into the container, where it is held while you breathe in slowly and progressively until your lungs are full. You should then hold in your breath before relaxing so the vapour has time to settle in your lungs.
This can make the medication more effective because much more of it reaches your lungs and much less stays in your mouth or is swallowed, where it has no effect on your lungs but is more likely to cause possible unwanted effects.
Spacers are also good for reducing the risk of thrush in the mouth or throat, which can be a side effect of some inhaled asthma preventer medicines.
Spacers can also be very helpful for people who find using inhalers difficult, such as young children. As spacers also improve the distribution of medication into the lungs, their regular use is preferred in many cases – particularly for preventer medications – even in people who use inhalers well.