Lung function measurements in children - copsac
Lung function measurements in children - copsac
Lung function measurements in children - copsac
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of a diagnosis of asthma: Frequent episodes of wheeze (more than once a month),<br />
activity-<strong>in</strong>duced cough or wheeze, nocturnal cough <strong>in</strong> periods without viral <strong>in</strong>fections,<br />
absence of seasonal variation <strong>in</strong> wheeze, and symptoms that persist after age 3.<br />
Diagnosis of asthma <strong>in</strong> <strong>children</strong> 5 years and younger presents a particularly difficult<br />
problem, s<strong>in</strong>ce the episodic wheez<strong>in</strong>g and cough also are common <strong>in</strong> <strong>children</strong> with a<br />
viral respiratory illness. Global Initiative for Asthma (GINA) describes three categories:<br />
1) Transient early wheez<strong>in</strong>g, which is often outgrown <strong>in</strong> the first 3 years and often<br />
associated with prematurity and parental smok<strong>in</strong>g.<br />
2) Persistent early-onset wheez<strong>in</strong>g (before age 3), typically <strong>children</strong> who have<br />
recurrent episodes of wheez<strong>in</strong>g associated with acute viral respiratory <strong>in</strong>fection,<br />
with no personal or parental atopy. Symptoms persist through school age. The<br />
cause of wheez<strong>in</strong>g episodes is usually respiratory syncytial virus <strong>in</strong> <strong>children</strong> < 2<br />
years of age.<br />
3) Late-onset wheez<strong>in</strong>g/asthma. These <strong>children</strong> have asthma that often persists <strong>in</strong>to<br />
adult life. They typically have an atopic background.<br />
In <strong>children</strong> younger than 5 years old, the diagnosis of asthma is mostly based on cl<strong>in</strong>ical<br />
judgment and assessment of symptoms. A useful method for confirm<strong>in</strong>g the diagnosis <strong>in</strong><br />
this age group is a trial of treatment with short-act<strong>in</strong>g bronchodilators and <strong>in</strong>haled<br />
glucocorticosteroids. For older <strong>children</strong> (school age) lung <strong>function</strong> and airway<br />
responsiveness are recommended as diagnostic measures (86).<br />
Risk factors<br />
Genetic factors (sex or atopic predisposition) may <strong>in</strong>fluence the development of asthma,<br />
whereas environmental factors (allergens, tobacco smoke or <strong>in</strong>fections) can trigger<br />
asthma symptoms or both. However, the mechanisms whereby they <strong>in</strong>fluence the<br />
development and expression of asthma are complex and <strong>in</strong>teractive. The maturation of<br />
the immune response and the tim<strong>in</strong>g of the <strong>in</strong>fectious exposures dur<strong>in</strong>g the first years of<br />
life may be an important factor modify<strong>in</strong>g the risk of asthma <strong>in</strong> the genetically<br />
susceptible person.<br />
The “hygiene hypothesis” has been debated <strong>in</strong> the recent years and used as an<br />
explanation for the <strong>in</strong>creas<strong>in</strong>g <strong>in</strong>cidence of asthma and allergy <strong>in</strong> the developed<br />
countries. The cornerstone <strong>in</strong> the hypothesis is that improvements <strong>in</strong> public health and<br />
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