Childhood Asthma Information for parents from a pediatrician

Childhood asthma, like asthma in adults, affects the medium and small airways (air tubes, bronchi). There is inflammation that means the airways react to certain triggers and become narrow. The narrowing of the airways causes difficulty breathing and a tightness in the chest.

Often there is wheezing, a whistling noise when the child breathes out. The airways in asthmatic children respond to drugs called bronchodilators which open them up again.

This page deals with asthma in toddlers and older children. For information on infants less than 2 years who wheeze, click here.

Why do the airways become narrow?

There are 3 main reasons the airways become narrow in childhood asthma, causing the difficulty breathing.

The underlying mechanism is inflammation of the airways but this causes:

the muscles around the air tubes (bronchi) to go into spasm and make the tube more narrow
the walls of the air tubes (bronchi) get swollen meaning the space in the middle for air flow is narrower
there is mucus production which blocks the airway

Why do Children get Asthma?

The main reason children get asthma is because it runs in the family. We call families with a tendency to asthma and other allergic diseases, like eczema and hayfever, atopic families.

Childhood asthma is also becoming more common even when there is not a strong family history and this is probably because of the lifestyle we have in developed countries. Factors such as pollution and spending more time inside at computers and television may contribute to this tendency.

What are the triggers that cause asthma in toddlers and older children?

The main triggers that cause the airways to narrow in childhood asthma are:

upper respiratory tract infections, like the common cold
exercise
allergy to house dust mite
cold weather
stress

What are asthma symptoms in a child?

The main symptom of childhood asthma is wheeze - this is a whistling noise that occurs when your toddler or older child breathes out.

Children may also have cough.

When the airways are narrow, it makes it hard to get air in and out of the lungs so you will notice your child working harder to breathe (for example, the ribs may be prominent as she breathes in and out) and she may be short of breath.

Asthma symptoms in a toddler or older child tend to be worse at night so often children will have a night-time cough or wake up with wheezing.

If exercise is the trigger, your child will cough and wheeze when she is running around and be short of breath, particularly if there is a cold wind.

Because, infection is a common trigger, children will often have a runny nose and then get cough and wheeze.

Do all children who wheeze have asthma?

No, just because your child has wheezy episodes it does not mean she has childhood asthma.

A large American Study (the Tucson Children's Respiratory Study) found that:

by 6 years of age, 49% of children had some wheezing - so it's common
19% of children had early transient wheeze (so they wheezed before the age of 3 years)
15% of children developed wheeze after the age of 3 years
14% of children still had wheeze at age 6 years

What this means is that a lot of children with wheeze stop wheezing and don't get childhood asthma, particularly if they are wheezing before the age of 3 years.

This is why some doctors are reluctant to call wheezing in infants and young toddlers asthma - they just call it wheeze or viral-induced wheeze.

I tend to call it childhood asthma if a child is over the age of 2 years and still has wheeze that responds to treatment. Of those children, I know a lot will grow out of the tendency to have asthma and most of them will not have adult asthma.

Which children are more likely to go on to have adult asthma?

You can't say for sure but the group of children who still wheeze at the age of 6 years and are more likely to have adult asthma are those:

who had more episodes of wheezing early in life
who have a family history of atopy (an allergic tendency)
who have a mother who has asthma
who have a mother who smokes

Are there any tests for childhood asthma?

There are no tests that can be used easily in pre-school children so doctors rely on the history of asthma symptoms in the child and how they respond to treatment.

Older children may use a peak flow meter or do formal lung function tests. Young children cannot manage these tests usually.

Is childhood asthma caused by food allergy?

Children who have asthma often have an atopic tendency so they can be allergic to food.

Some children get asthma as a symptom of the allergy so an infant who is allergic to milk might get asthma symptoms when she has milk. In these cases, it is usually clear that the food has caused the asthma and it should then be avoided.

In most cases, childhood asthma is not caused by a food allergy.

Is asthma caused by dust allergy?

In many children, house dust mite, which are present in the normal dust we all have in our houses, cause asthma symptoms. If your child has an allergy to house dust mite, which can be shown with skin prick tests, you can try to reduce house dust mites but there is no evidence that doing so will reduce asthma symptoms.

What can I do to reduce house dust mite?

There are a number of measures that reduce house dust mite:

Vacuum regularly - make sure your vacuum has a filter
Dust with a wet cloth ( you don't want to use a dry one and put the dust in the air)
Get rid of fluffy toys that can gather dust
Cover the mattress and pillow with closely woven breathable fabric designed to reduce house dust mite
Remove carpets - only resort to this expensive option if you are sure your child has a strong allergy to house dust mite

However, as already stated, a review of the literature has found no evidence that any of these measures work in reducing asthma symptoms. So, do not spend a lot of money trying to reduce house dust mite.

Should I restrict activity if my child has asthma?

No. The important thing is to manage the asthma and let your child partake in all the normal childhood activities.

Swimming is a good sport for childhood asthma sufferers as it helps breathing.

Does having pets increase the chances of my child having asthma?

No. Being exposed to pets, particularly dogs, in the first year of life may actually help prevent wheeze and asthma. However, some asthmatic children will be sensitive to pets and if that is the case, you will see the symptoms increase as there is more contact with the pet. You might have to find a new home for your pet if this is the case with your child.

Is there anything I can do to prevent my child getting asthma?

In children with high risk for childhood asthma, such as having asthma and allergy in the family, there is some evidence that the following reduce the chances of developing asthma:

breast-feeding
reducing the exposure to indoor allergens, such as house dust mite
reducing the exposure to maternal smoking

So, you as a mother can stop smoking, breast-feed your child and keep dust in your house to a minimum.

References

Milgrom H. Childhood Asthma: Breakthroughs and Challenges. Chapter in "Advances in Pediatrics" Vol 53. Mosby 2006 ISBN 1 4160 3324 6
Smith HE, Frew AJ. Allergy. Your Questions Answered. Churchill Livingstone 2003. ISBN 0 4430 7291 4
G�tzsche PC, Johansen HK. House dust mite control measures for asthma. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD001187. DOI: 10.1002/14651858.CD001187.pub3