Pediatric asthma
Spot the real thing
by Richard Haber, MD
Vol.18, No.04, April 2010

Asthma in young children is not the same as asthma in adolescents and adults, and one of the major differences is in the art of diagnosis. In the Asthma Centre of our hospital, the Montreal Children’s Hospital, approximately 65% of children seen in consultation are under the age of 5-6 years. Because of their youth, objective measures of airway obstruction (pulmonary function tests) can’t be done since they require a level of cooperation a young child cannot give. Secondly, in the very young (< 3 years) there are two distinct patterns of wheezing: the episodic viral wheezer (see this column, p. 16, April 2009) and the truly asthmatic wheezer. The treatment and prognosis of these distinct populations are different. Pediatric asthma is a clinical diagnosis based on the child’s history and the family history, along with the physical exam and corroborative laboratory investigations such as IgE, eosinophil count and allergy skin tests.

Always keep in mind, especially at the first visit for a wheezing episode, that there are other, albeit rarer, causes of wheezing in young children besides viruses: foreign body, cystic fibrosis, vascular rings and cardiac disease.

Diagnostic criteria

The following criteria are helpful in diagnosing asthma in young kids: wheezing after 1 year of life, recurrent wheezing (3 or more episodes), chronic cough (especially nocturnal or exercise-induced), and response to anti-asthma medications.1 An Asthma Predictive Index has been developed from the Tucson Children’s Respiratory Study.2 Seventy-six percent of children under 3 years of age with a positive predictive index were more likely to have persistent wheezing (asthma) after the age of 6, and 97% of kids with a negative predictive index did not have persistent wheezing at the age of 6.2

A positive index is:

  • 4 or more episodes of wheezing in the past year + one major criterion (parental or MD-diagnosed asthma, MD-diagnosed eczema)
  • or, 2 minor criteria (MD-diagnosed allergic rhinitis, wheezing apart from colds, eosinophilia ( > 4%).

To distinguish episodic viral wheezers from true asthmatics, an index based on the history and clinical examination is useful. The distinction is important because the treatment for the two conditions differs.

The young child who wheezes only with viral infections doesn’t need to be treated with inhaled corticosteroids, as there’s no ongoing inflammation between viral infections. In fact, there’s no good evidence telling us the best way to treat these kids. Standard treatment of the viral wheezer severe enough to go to the emergency room includes a short course of oral steroids and short-acting beta-agonists. Milder episodic viral wheezers may be treated with short-acting beta-agonists on a prn basis. The viral wheezer doesn’t need to be treated with antibiotics unless there’s a superimposed bacterial infection (e.g. otitis media). I’ve frequently seen these children labelled as “bronchitis” cases and given a course of antibiotics!

In the asthmatic child, however, there are ongoing inflammatory changes in the airways between wheezing episodes. This child with asthma will often require inhaled corticosteroids, along with a short-acting beta agonist. The treatment of asthma is well-described in the Consensus Guidelines and inhaled corticosteroids are recommended as the mainstay of therapy in kids with asthma.1

As one can see from Figure 1, underlying all our treatments for asthma are environmental control — especially assuring that the child has a smoke-free environment. This may require counselling and treatment for the smoking parent. Dust mite precautions have been shown to be effective in helping the child achieve control of his or her asthma. Eliminating animals from the environment if the child is allergic to them can be helpful although often difficult to achieve. Educate parents at each visit. It’s surprising how many parents confuse the ICS with the beta-agonist. They should review the two different types of medication used in asthma control and the correct way of administering them through an aerochamber at every visit. Finally, there is Level 1 evidence for the use of a written Action Plan and all asthmatic patients should have one in order to achieve optimal control.

Richard Haber, MD, FAAP, FRCPC is an associate professor of pediatrics at McGill University and the Director of the Pediatric Consultation Centre at the Montreal Children’s Hospital.

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References
  1. Canadian Asthma Consensus Guidelines, 2003 and Canadian Pediatric Asthma Consensus Guidelines, 2003, summarized in CMAJ 2005;173 (6 suppl): S1-S56.
  2. Castro-Rodriguez, JA et al. Am J Respir Crit Care Med vol 162, pp1403-6, 2000.
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