Asthma

Asthma

What is asthma?

Asthma is an inflammatory lung disease that causes recurring breathing problems in those affected. During an asthma attack, the air passages in the lungs narrow or contract — various types of irritants in the atmosphere can trigger this contraction response. The inner lining of the bronchi (branches of the airway) also becomes inflamed and swells and an excess amount of phlegm (mucus) is produced. All of this results in breathing becoming more difficult.

What causes asthma?

Asthma is most likely a result of genetic susceptibility. About one-third of all people with asthma share the problem with another member of their immediate family. The risk of having an asthmatic child may be six times higher if both parents have a history of asthma than if just one had the disease.

There has been a dramatic rise in the incidence of asthma in industrial countries, including Ireland, even though outdoor air pollutants are decreasing. There are several possible explanations — for example, children now spend more time indoors and are overexposed to indoor allergens. Also, modern energy-efficient homes may result in dust mites being trapped inside them. In addition, more low-birth-weight babies are surviving and they may be more susceptible to asthma.

However, other respiratory diseases, sinusitis and ear infections are also increasing, which suggests that airborne or environmental factors may indeed be involved. Allergies may also play a role.

Who develops asthma?

Asthma is a very common illness, estimated to affect 5%-10% of adults and 10%-15% of children, and the numbers are rising. Children who develop asthma usually belong to a group described as ‘atopic’ — this means that the child has inherited a gene that makes them liable to allergy.

An allergic person will develop some kind of allergic illness if they encounter an allergen that triggers an allergic response — the allergic illness may be asthma, hay fever or eczema. They mostly start in childhood, but can sometimes develop later. Many children with asthma will "grow out of it".

Asthma that begins in adulthood is usually the intrinsic or non-allergic type, although adults can develop allergic asthma.

What triggers an asthma attack?

Any number of factors can trigger an asthma attack, depending on the person concerned, but the potential triggers can generally be divided into two groups:

What are the signs of an asthma attack?

How is asthma diagnosed?

Asthma is underdiagnosed for a number of reasons — the symptoms are very similar to conditions such as emphysema, bronchitis, and lower respiratory infections, so the diagnosis may be missed.

If the symptoms are mild, with the only sign a cough at night or following exercise, the sufferer may not suspect asthma. Your doctor will take your medical history, carry out a thorough medical examination, and perform lung function tests to confirm the diagnosis.

The peak expiratory flow is the simplest lung function test and involves blowing air out as hard as possible through a Peak Flow Meter and recording the peak expiratory flow rate (PEFR). Other tests may also be performed — for example, spirometry (using an instrument that measures the air taken into and out of the lungs), chest X-rays, and sometimes blood and allergy tests.

How is asthma treated?

There is no cure for asthma, so the aim of treatment is to manage the symptoms so that they do not interfere with your quality of life or seriously threaten your health.

Trigger factors

The first step towards achieving long-term control of asthma is to avoid trigger factors as much as possible. Avoid exposure to tobacco smoke and people who have colds and ask your doctor for advice on minimising the effect of dust mites, animal hair and mould in your home.

Medication

Medication is the mainstay of asthma management in most patients and is used to control inflammation and to relieve symptoms. The drug treatment chosen will vary from person to person, depending on the frequency, severity, and particular triggers of each person’s attacks.

There are two groups of medication:

Relievers (Bronchodilators) work to relieve symptoms and are generally taken by inhaler. Many of the commonly used relievers come in blue inhaler containers. Short-acting relievers (so-called because their effect usually lasts for four hours) work by relaxing the smooth muscle of the airways, thereby easing symptoms and protecting against the type of asthma triggered by exercise or contact with allergens. Long-acting relievers (so-called because their effect usually lasts for up to 12 hours) are usually prescribed for people whose symptoms are not controlled by moderate or high doses of inhaled steroids and short-acting relievers. If you are using bronchodilators more than once a day, you should tell your doctor as your treatment may need to be adjusted or changed. Beta2-agonists, anticholinergics and theophylline are all types of bronchodilators.

Preventers are anti-inflammatory medications (commonly, steroids or corticosteroids). Sometimes, the inflammatory component of asthma may need to be specifically treated and this is commonly undertaken with inhaled steroids. These “preventers” generally come in brown inhaler containers. The effects may not be felt immediately, and you must take them for several weeks before you get the full benefit. Other types of anti-inflammatory medications may be used for children, especially those under five years of age. Oral steroid tablets may be prescribed for bad attacks. Steroids are powerful drugs, but their safety in asthma has been established.

Very often, a combination of Preventers and Relievers is recommended. Some asthma inhalers now combine both an anti-inflammatory medication and a bronchodilator, and are used to prevent an asthma attack in patients whose symptoms are not well-controlled, or who are already using the two treatments. These combined inhalers are aimed at simplifying asthma control in these patients.

Monoclonal antibodies

A new treatment for people with severe persistent allergic asthma – called a unique humanised monoclonal anti-IgE antibody – was introduced in Ireland in 2005. It is a highly specialised treatment, which is given by injection either every two or every four weeks. Only certain patients are suitable for the treatment and they will need to undergo some tests before the medication can be prescribed by their doctor.

The treatment works by blocking the action of the IgE antibody, therefore targeting the underlying mechanism of allergic asthma. The aim is to prevent the onset or worsening of symptoms.

How do I choose an inhaler device?

There are several different types of inhaler devices available and it is important to choose one that you find easy to use, so that your treatment is effective. Your doctor and the asthma nurse (if available) will advise you in the correct choice for you or your child.

Aerosol inhalers

Also known as pressurised metered dose inhalers (pMDIs), the medication is mixed with a propellant liquid that evaporates as the aerosol is used. The drug is released when you press the trigger, you breathe in slowly, hold your breath for 10 seconds and then breathe out.

Spacers

These are effectively ‘holding chambers’ attached to the pMDI. You breathe in the medication from the spacer, so they are particularly useful for young children and elderly people because you don’t have to worry about aerosol firing/breathing-in co-ordination.

Dry powder inhalers

These devices deliver the drug in dry powder form rather than as an aerosol-propelled liquid. Many people find them easier to use than pMDIs, as you don't have to worry about aerosol firing/breathing-in co-ordination.

Nebulisers

These are devices that use pressurised air to turn a liquid medication into a fine mist for inhalation (if you have ever received emergency treatment for asthma, you have probably used a nebuliser). These devices produce a mist of the medication by passing a jet of compressed air over it. You breathe the mist in through a face mask or a mouthpiece. They are often recommended for very young children or if you need to take large doses of reliever medicines.

What can I do?

What is the outlook?

Asthma cannot be cured but it can be managed effectively so that it does not interfere with your lifestyle. It is vital that you stop smoking and take all the medication prescribed by your doctor, even if you feel well. While it is a generally well-controlled disease, this is not to say that it can be taken too lightly. Failure to follow advice on your asthma medication can lead to extremely serious complications, and in some extreme cases, death. The old saying that 'an ounce of prevention is worth a pound of cure' fits asthma management to a tee.

 

Reviewed: September 25, 2006