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Childhood asthma
Hot topics in diagnosing and managing
kids who wheeze
An interview with Zave Chad, MD
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Why
is early diagnosis of asthma such a hot topic?
Most asthma starts in childhood, under age 5, and the severity at
that early stage is a good predictor of long-term prognosis into
adulthood. Consequently, it's becoming increasingly important to
identify children with asthma as early as possible -- well before
age 7 -- so that they can begin treatment and, hopefully, change
the course of the disease. Studies show that early-onset wheezers
who receive inhaled corticosteroids (ICSs) sooner do better than
those starting these meds later. It's clear that we should identify
the condition early and initiate therapy with ICSs as soon as the
diagnosis is made -- exactly as recommended in the current Canadian
guidelines on pediatric asthma (CMAJ 2005;173:S12-4).
Which
children will outgrow their asthma -- and which won't?
That's another key issue -- we're increasingly aware that not all
asthmas are alike. There are three types of presentation in children:
- early-onset transient asthma: infants who
wheeze with infections, but usually grow out of it
- early-onset persistent asthma: wheezing
starts in infancy, but the asthma continues into later childhood
and adulthood
- delayed-onset persistent asthma: symptoms
begin after 3-4 years of age, and don't go away as the child gets
older.
It's important to distinguish these types
because kids in the first category, the transient wheezers, don't
have to be treated quite as aggressively as those in the other two.
These children typically don't have any other allergies, nor do
any close family members, and they have mothers who smoked during
pregnancy. One theory is that these children wheeze because they
were born with smaller airways due to fetal exposure to toxins from
cigarette smoke, and that the problem resolves as the airways grow
larger.
How
is asthma diagnosed in younger children?
Since breathing tests can't be done in children below age 6, the
diagnosis of asthma in this age group is purely clinical, based
on history, physical exam, and symptom patterns.
Taking a thorough patient and family history
is essential. When first seeing children who are wheezing, be sure
to ask about atopic disease -- there's a strong interrelationship
between asthma and allergic conditions. If kids have allergies,
such as food sensitivities or eczema, you can predict that they
won't be transient wheezers. The current consensus is that the more
allergic an individual is, the greater the chance of developing
a persistent and clinically significant form of asthma. A number
of longitudinal studies have shown that younger children who have
positive skin tests are significantly more likely to have bronchial
hyperreactivity once they're old enough to perform pulmonary function
tests. Conversely, asthma is a major risk factor for more severe
allergic reactions, including anaphylaxis.
In addition, don't forget to ask about environmental
factors that may be triggering asthma attacks. Common culprits include
smoking in the home, pets, dampness leading to mould, carpeting,
bedding and stuffed animals harbouring dust mites.
Which
symptoms should we look for?
Remember, wheezing and shortness of breath aren't the only symptoms
of asthma -- frequent coughing is another important clue. This can
include a persistent cough with colds; a reactive cough triggered
by cold air, high humidity, exercise, laughing, crying, or emotional
excitement; and coughing at night. Of course, not all cough is asthma;
the differential diagnoses should be considered as well, such as
cystic fibrosis for severe coughing and breathing difficulties,
and gastrointestinal reflux disease, which is often overlooked.
Similarly, not all wheezing is asthma -- foreign
bodies or strictures are a possible cause -- and it's crucial to
distinguish between problems heard when inhaling vs exhaling. For
example, enlarged adenoids tend to produce inspiratory "heavy breathing"
at night, whereas the asthmatic wheeze occurs on exhaling.
Don't overlook coexistent nasal symptoms when
managing children with asthma. Studies show that treating nasal
problems improves asthma and vice-versa, which makes sense, given
that the nose plays such a key role in protecting the lungs from
micro-organisms, allergens and irritants.
What
investigations can guide asthma management?
Skin testing is particularly useful in children who are known to
have allergic conditions like eczema, food allergies or hay fever,
and/or a family history of atopy in close relatives. Once you know
the full spectrum of what they're sensitive to, proper environmental
precautions can be put in place for many allergens, especially dust
mites, mould or animal dander. Other allergens, such as pollen,
perhaps can't be eliminated unless the patient can move to Arizona
or the High Arctic, but at least you can anticipate the time of
year when problems are likely to occur and ensure that the child
stays on ICSs during that period.
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