Childhood asthma
Hot topics in diagnosing and managing kids who wheeze
by Zave Chad, MD
Vol.14, No.12, December 2006

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.

What's the role of viral infections in childhood asthma?
Viral infections are emerging as key players in asthma development. We used to think that respiratory syncytial virus (RSV) was the primary pathogen involved in infants, while rhinovirus infection was seen as a marker for future asthma in older kids only -- but newer research indicates that rhinovirus is at least as important as RSV in babies and toddlers. It's also been found that the epithelial airway lining in asthma patients is less able to clear viruses than that of normal airways. Consequently, these infectious agents stay much longer in the lungs and can spread to other kids. What's more, inflammatory reactions actually raise the number of viral receptors in the airways, which will lead to more infections in people with asthma. This may explain the familiar "September epidemic" of asthma episodes and hospitalizations, which coincides with back-to-school outbreaks of colds, caused mainly by rhinoviruses. Many kids with asthma also have seasonal allergies to ragweed, mould and other fall allergens.

All of these factors work together to create a "perfect storm" for fall asthma attacks -- but recognizing this pattern can help to prevent episodes. For example, many children are told to take their controller medications in the fall and winter to prevent asthma triggered by colds and then to stop them in the summer. They're often advised to resume their meds at the first sign of a cold, but that's probably too late -- they should be starting a few weeks before the anticipated cold season. Most children showing up in emergency rooms (ERs) for asthma haven't been taking their ICSs; those starting their medications in late August or early September may have milder symptoms (if any) that wouldn't warrant hospitalization.

When is immunotherapy indicated for asthma?
The latest asthma guidelines indicate that there's level I evidence supporting two forms of treatment:

  • controller/preventer medications (mainly ICSs) in persistent asthma
  • immunotherapy.

Immunotherapy isn't used much in children with asthma, but research shows that it can be surprisingly effective. As well, the earlier it's initiated, the greater the benefit -- early immunotherapy can even prevent the onset of other allergies, such as against dust mites. On the other hand, allergy shots are time-consuming and painful, which probably limits their use in kids.

Ultimately, immunotherapy shouldn't be a first-line approach, and it can't replace other measures (e.g. environmental controls and controller medications), but it may be quite useful and should be considered if certain specific criteria are met (see Table). The other situation where allergy shots can play a role is in children with asthma and coexisting allergic rhinitis. Since there's a common airway inflammation affecting the lungs and the nose, immunotherapy will actually treat both components. Often, however, specific environmental precautions and/or appropriate low doses of asthma controllers are enough to improve the sypmtoms, and it's not necessary to take that next step.

When are leukotriene inhibitors appropriate?
In the most recent guidelines, leukotriene inhibitors aren't recommended as first-line anti-inflammatory asthma controllers, but are considered an alternative for patients who can't or won't use ICSs. Although these agents are weaker anti-inflammatories, they're better than none at all. But since these recommendations were written, two articles have been published showing that leukotriene inhibitors may have benefits in viral infection-induced asthma, when used on an as-needed basis. It's worth noting that, in contrast, there's no clear evidence supporting intermittent use of ICSs for virus-associated wheezing -- yet over half of patients may be taking them in this way.

Leukotriene inhibitors are also appropriate for kids with asthma and allergic rhinitis; since they're systemic anti-inflammatories, they work on each affected site. Often, children using an inhaler for their lungs and a topical corticosteroid for their nose can cut down the steroid doses for both organs by taking a leukotriene inhibitor, such as montelukast. Keep in mind, however, that this class of anti-inflammatory won't work in everyone -- benefits will generally show up within a couple of weeks, and seeing no results after a month can be considered a treatment failure.

What's an asthma action plan? Do we have to create one for every patient?
The current approach to asthma management is to establish an individual's symptom pattern, based on a comprehensive history, and then organize a treatment plan that anticipates high-risk periods and situations. Depending on the case, these might call for starting an ICS before the child's "asthma season" -- or raising the dose if he or she is already taking it year-round -- to prevent attacks.

There's a certain amount of trial and error involved, but it's mainly a time-consuming task to gather the relevant clues from the history. This information is essential for implementing environmental controls and formulating an individualized asthma action plan for the child. These plans have proven themselves to be very helpful -- and they don't have to be set up according to the commonly used "green zone," meaning symptom-free, "yellow zone," indicating there are warning signs, and "red zone," which represents danger and requires going immediately to the nearest ER. Templates for action plans are available from the Asthma Society of Canada (www.asthma.ca/adults/control/actionPlan.php), the Canadian Lung Association (www.lung.ca/_resources/asthma_action_plan.pdf) and other internet sites, as well as neighbourhood hospitals and Lung Association offices. Alternatively, some physicians may prefer to draw the plans up themselves -- I usually write one out as I'm talking to the patient. The key elements are: which medications the patient is taking, how these agents act, especially the differences between controller and reliever drugs, and what to do if they aren't working. Patients need something in writing, because people easily forget, especially when they're being bombarded with new information. Other resources that can be useful to give to parents include books on asthma and lists of reliable websites.

What's the best way to educate patients on asthma?
If there's an asthma education centre in your community, by all means make use of it -- these centres are complementary to the primary-care provider, not a replacement. Unfortunately, research shows that many people don't go when they're referred to such facilities. As a result, some authorities suggest that the best teaching is done on-site, whether in the ER or the office, when the patients are being seen for their problem.

Dr. Alan Kaplan, a Canadian family physician, has developed a practical solution for asthma education when time is limited: bring patients back for several shorter visits, rather than trying to do it all in one sitting. For example, one visit can focus on explaining the difference between controllers and relievers, another on how to follow the action plan, and a separate session on instituting environmental controls. Each "lesson" adds to the child's and parents' understanding of how to manage this chronic condition.

Another effective educational tool is referral to a specialist, which can help to reinforce your message and convince parents that you're managing their child appropriately. Even if the consultant switches medications, this can usually be explained as tailoring to changes in the child's condition over time.

And don't forget to teach patients how to use their inhalers. Dry-powder inhalers (e.g. Turbohaler, Diskhaler) aren't useful for children under age 5 -- they can't consistently generate enough inspiratory flow to actuate these devices. Instead, these younger kids should be prescribed metered-dose inhalers (MDIs) with spacers. Be aware that children who are crying and fighting the spacer aren't actually getting very much medicine into their lungs. People often think that if they wait for a sobbing child to take a big breath, he or she will inhale a good amount, but studies show the opposite is true. Parents need to be told about this issue, which also has to be considered when you're deciding which device to use.

In addition, these devices have to be sized appropriately -- I've seen 8-year-olds who are still using Aerochambers with the yellow (medium) facemask, when they should be using blue (large) ones. Be sure to have samples of all the devices in the office, including placebo MDIs, to be able to train patients effectively in how to use them properly. Cost is also a factor, unfortunately -- it's always wise to find out whether the family has insurance coverage, and what kind, before deciding which medications to prescribe.

How often should we do follow-up?
Many specialists recommend viewing each initiation of a medication as a trial that has to be regularly assessed to see if it's working -- and if it isn't, be prepared to reconsider the treatment plan. The frequency of reassessment depends on the individual's symptom pattern and disease stability. Certainly, follow-up is warranted every 6 months in children with active asthma, and every 3 months in those with more severe disease. Kids who've been in and out of hospital recently might need to be seen even more frequently to stabilize their condition.

In contrast, patients with a pollen allergy could be given an action plan during a winter visit, to be implemented in spring and summer, and then told to return for re-evaluation after the pollen season is over. Another scenario is infection-related asthma, which is common in spring, fall and winter; I typically see children with this problem during the fall cold season, and then follow up in January to determine if their plan should be changed for the rest of the winter.

What should we do when kids have to go to the ER?
Unfortunately, many children who repeatedly end up in the ER for their asthma don't have a primary-care physician to ensure proper follow-up and education. The majority of children with asthma, though, rarely require ER visits -- and when they do, their regular doctors should thoroughly review the circumstances leading up to the hospitalization.

It's vital to find out what went wrong -- what happened during the episode, the symptoms they had prior to it, and the medications they were taking at the time -- and to instruct parents on more aggressive measures to deal with future events. Asking detailed questions about the symptoms is also important in establishing and clarifying the diagnosis. In some cases, a child may have been coughing for several weeks before going to the ER, but the parents didn't realize this was an asthma symptom.

Zave Chad, MD, FRCPC received his medical degree from McGill University, where he went on to train in pediatrics, as well as allergy and immunology. He is Associate Professor of Pediatrics at the University of Ottawa and is on staff at the Children's Hospital of Eastern Ontario.

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When to consider immunotherapy
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