Lung function measurements in children - copsac

of a diagnosis of asthma: Frequent episodes of wheeze (more than once a month),
activity-induced cough or wheeze, nocturnal cough in periods without viral infections,
absence of seasonal variation in wheeze, and symptoms that persist after age 3.
Diagnosis of asthma in children 5 years and younger presents a particularly difficult
problem, since the episodic wheezing and cough also are common in children with a
viral respiratory illness. Global Initiative for Asthma (GINA) describes three categories:
1) Transient early wheezing, which is often outgrown in the first 3 years and often
associated with prematurity and parental smoking.
2) Persistent early-onset wheezing (before age 3), typically children who have
recurrent episodes of wheezing associated with acute viral respiratory infection,
with no personal or parental atopy. Symptoms persist through school age. The
cause of wheezing episodes is usually respiratory syncytial virus in children < 2
years of age.
3) Late-onset wheezing/asthma. These children have asthma that often persists into
adult life. They typically have an atopic background.
In children younger than 5 years old, the diagnosis of asthma is mostly based on clinical
judgment and assessment of symptoms. A useful method for confirming the diagnosis in
this age group is a trial of treatment with short-acting bronchodilators and inhaled
glucocorticosteroids. For older children (school age) lung function and airway
responsiveness are recommended as diagnostic measures (86).
Risk factors
Genetic factors (sex or atopic predisposition) may influence the development of asthma,
whereas environmental factors (allergens, tobacco smoke or infections) can trigger
asthma symptoms or both. However, the mechanisms whereby they influence the
development and expression of asthma are complex and interactive. The maturation of
the immune response and the timing of the infectious exposures during the first years of
life may be an important factor modifying the risk of asthma in the genetically
susceptible person.
The “hygiene hypothesis” has been debated in the recent years and used as an
explanation for the increasing incidence of asthma and allergy in the developed
countries. The cornerstone in the hypothesis is that improvements in public health and
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