Demystifying Pediatric Asthma
A Practical Approach to Evaluation and Management
By Deborah Keye, PA-C, MMSc, and Robert J. Geller, MD, FAAP
Pediatric asthma now affects almost 5 million children in the United States, making it one of the most common chronic pediatric diseases.1 Asthma exacerbations are frequently unpredictable and interfere with the usual activities of childhood. Asthma is a serious disease that is frequently taken lightly, yet every year it takes the lives of many children.
Alarmingly, the prevalence of and mortality rate from pediatric asthma continue to rise in spite of our progress in understanding of the disease. A Centers for Disease Control and Prevention survey on self-reported asthma in people ages 5 to 34 years shows that its prevalence increased by 75 percent from 1980 to 1994 throughout the nation.2 Similarly, the death rate from pediatric asthma from 1980 to 1993 has increased, especially among high-risk groups such as African-American children, who are almost six times as likely to die from asthma as the average child, although the reason for this remains poorly understood.
The consensus of experts on pediatric asthma is that it is an underdiagnosed disease that is consequently undertreated. The risk of sudden death from asthma certainly should provoke concern in the medical provider, and the potential for lung damage that is difficult or impossible to reverse should further motivate the clinician to act decisively.
How can health care providers evaluate and treat pediatric asthma effectively? The answer involves the use of a three-stage process.
First, we must take good histories and look for clues to the presence of asthma, and we must pursue the suggestion of possible asthma with objective measures such as spirometry or other measures of pulmonary function.
Second, once the data support a diagnosis of asthma, we must respond by prescribing the appropriate medications, which usually include one or more controller agents (such as inhaled corticosteroids, leukotriene inhibitors or possibly theophylline), in addition to a short-acting bronchodilator such as albuterol.
Third, we must reassess the patient’s asthma control regularly and work with the patient to develop a program that achieves maximal asthma control while avoiding adverse effects and minimizing the complexity of the regimen.
Permanent changes from asthma, referred to collectively as “remodeling,” include collagen deposition in the submucosa of the lung, increased mucus production and hypertrophy of the smooth bronchial muscle. Daily inhaled corticosteroids are thought to be indicated for patients with persistent asthma because, to date, these are the only drugs that have been demonstrated to prevent remodeling and minimize inflammation in the lung.4,5
Deonte is a 10-year-old African-American boy who presents as a new patient. He and his mother want some answers about his breathing problems. He was diagnosed with respiratory syncytial virus bronchiolitis at age 15 months and has had problems with wheezing ever since. In the past year, he has developed wheezing during soccer and has had to sit out during a significant portion of each game to “catch his breath.” Deonte’s primary care provider has told Deonte’s mother that her son may have asthma. She wants a second opinion.
As you elicit a more thorough history, your concern about asthma rises. In addition to his episodic wheezing and his exercise symptoms, he also has difficulty sleeping through the night because of coughing episodes three nights per week. His father also has asthma. You auscultate his lungs during tidal breathing and forced expiration; breath sounds are clear in all fields with good air movement. Wheezing is not heard. There is no prolonged expiratory phase. Given this apparent discrepancy between history and exam, what is your next step?
At this point, remember that the physical exam findings frequently underestimate the severity of asthma, given the intermittent nature of bronchospasm in asthma. It is therefore imperative to perform lung function testing to look for evidence of asthma, such as reversible obstruction to airflow and small airway abnormalities.
Without an objective way to measure the severity of airway obstruction and other lung dysfunction, many children may be diagnosed with a less severe category of asthma or remain undiagnosed altogether, because it is often difficult to assess the severity of asthma by history and physical alone.6,7 To diagnose asthma with lung function testing, not only does an obstructive pattern need to be present, but also the obstruction must be reversible (at least partially, on most occasions) after a bronchodilator is given.8 It is also important to assess pulmonary function at every follow-up visit, or at least periodically, to assess the efficacy of a treatment regimen.
Spirometry is our preferred method of lung function testing, because it measures large and small airway obstruction, it is simple to perform, it is non-invasive, it is relatively inexpensive and it can be performed in the office with only a small capital investment.
The spirometry example that could represent Deonte’s results shows a decrease from his predicted values for forced expiratory volume in one second (FEV1), the FEV1/FVC ratio and the forced expiratory flow rate during mid-expiration (FEF25-75).
Predicted values for children have been derived from studies on normal populations and are based on age, race, sex and height. In asthma that is not properly treated and controlled, a characteristic pattern of abnormalities will be seen on spirometry.
FVC is the total amount of air that is forcibly expelled after taking a maximal inspiration. It is a large airway measurement expressed in liters. FEV1 is the amount of air that is forcibly expired during the first second of the FVC, and is also a large airway measurement expressed in liters.
The FEV1/FVC ratio compares how much air is forcibly expired in the first second over the total amount of air being forcibly expired. In a healthy lung, most of the air will be expired in the first second. In these large airway measurements, normal values are 80 percent or higher of predicted values for FVC, FEV1 and FEV1/FVC and 75 percent of predicted FEF25-75.
The FEF25-75 is the rate of air being forcibly expired during the middle half of the forced expiration. This measurement, when the patient cooperates well with the spirometry maneuver, correlates well with small airway inflammation and is expressed in liters per second.
PEAK FLOW METERS
A peak flow meter is another way to measure lung function. It measures large airway obstruction in liters per minute, known as peak expiratory flow rate. Because a peak flow meter does not measure small airway inflammation and its results can hide small airway abnormalities, the severity of the asthma may be underestimated.9 Therefore, we reserve its use for times when the patient cannot perform spirometry or when spirometry is not available.
However, peak flow measurement is an excellent objective tool to monitor asthma at home, and each child who is likely to be able to master its use (probably age 5 or older) should be taught how to use it before leaving the office.
PEAK FLOW VALUES
Deonte is given instructions on how to use a peak flow meter in conjunction with the green-yellow-red zone peak flow action plan in a diary. His normal peak flow values are predicted initially by using a population norm, such as those of Polgar.10 The Polgar norms can also be quickly estimated by using the shortcut equation PF (L)=5.25 x height (cm) – 426. If the patient is Asian or African-American, this value should be reduced by 15percent. (This formula is applicable for heights from 110 cm to 160 cm.)
Since 10-year-old African-American Deonte is 130 cm, his predicted peak flow is 218 L/min. His green zone is 80 percent or higher, which is 174 L/min or higher. His peak flow at your office today is 160 L/min, which falls into the yellow zone range (60 percent to 80 percent of predicted peak flow).
Once his history, physical exam and pulmonary function test results are obtained, it is time to decide which medical regimen to utilize. To choose the appropriate medicines for Deonte, the severity of his asthma must be assessed. The currently recommended classification system has been promulgated in the National Institutes of Health (NIH) Expert Panel Report 2 (EPR2) on Diagnosis and Management of Asthma (Table 2).11
Deonte is a moderate persistent asthmatic because he has limitations in his physical activity, has nocturnal symptoms more than once a week, and his FEV1 is 65 percent of his predicted value. It is important to note that the severity of asthma is assessed before any treatment has been initiated. The guidelines also classify a patient’s asthma based on the most severe symptoms he or she is experiencing. For example, if a child presents with a history of some symptoms falling into the mild-intermittent category and some in the mild-persistent category, then the child would be assessed as a mild-persistent asthmatic.
The recommended initial strategy for treating Deonte’s moderate persistent asthma, according to the NIH EPR2 guidelines,12 is to place him on a daily medium-dose inhaled corticosteroid and a short-acting bronchodilator that can be used before exercise and every six hours as needed for symptomatic relief (Table 3).
If Deonte is still symptomatic, or his lung function is not improving using this regimen on a regular basis for at least three to four weeks, caregivers may consider increasing the number of puffs of his inhaled corticosteroid per day, or adding a second maintenance medicine to his regimen such as a long-acting bronchodilator, a leukotriene inhibitor, a mast cell stabilizer or, as a last resort, theophylline. It is necessary to have follow-up visits with Deonte until he and his parents all are satisfied with the results of his treatment regimen. In this case, specific goals include being asymptomatic during soccer and nighttime, no emergency department visits or hospitalizations and normal spirometry.
The next step is choosing a specific inhaled steroid for Deonte. Since each inhaled corticosteroid has its own unique potency or effect of the drug per microgram of drug, caregivers must choose the appropriate number of puffs per day that equals a medium dose. Caregivers attempt to minimize the risk of non-adherence by picking an agent that does not have an offensive taste to the specific patient and by administering all medications either once or twice a day whenever possible (Table 4).13 Possible choices we would present to the patient might include eight puffs of triamcinolone 200 µg/puff daily divided b.i.d., four puffs fluticasone 110 µg/puff divided b.i.d., two puffs fluticasone 220 µg/puff once daily or two clicks of budesonide once daily.
If Deonte were assessed as a mild-intermittent asthmatic, then he would need to be prescribed a short-acting bronchodilator to use every six hours p.r.n. cough, wheezing or dyspnea. If he starts using his bronchodilator more than twice a week, or more than twice a month at night for exacerbations, or if he develops exercise symptoms, then he should be treated as a mild-persistent asthmatic.
A mild persistent asthmatic needs a daily maintenance medicine to keep symptoms under control. The three maintenance drugs to consider are a mast cell stabilizer, a leukotriene inhibitor or a low-dose inhaled corticosteroid. Remember that inhaled corticosteroids are the only drugs to date that have been shown to prevent remodeling in the lung and minimize inflammation. In our opinion, this is the first-line maintenance drug of choice for mild persistent asthmatics.
If Deonte was a severe persistent asthmatic, the NIH EPR2 standard of care is to prescribe a daily high dose inhaled corticosteroid. Unfortunately, many asthmatics in this category are not controlled by this drug alone and need a second- and third-line maintenance medicine in addition. Second line drugs to add to the daily regimen are leukotriene inhibitors or long acting bronchodilators. If adding these two drugs is still not sufficient, adding theophylline is the next step. Oral corticosteroids should only be considered as maintenance therapy if the combination of all other maintenance drugs has failed to control symptoms or improve lung function. When used long-term, these drugs have known serious side effects such as osteoporosis, adrenal suppression and growth suppression.14
One last important thing to decide on when using conventional metered-dose inhaler (MDI) agents is which spacer to teach him to use. Because he is probably old enough to hold his breath for 10 seconds, we decided to prescribe an Optihaler with both MDIs.
Spacers are important tools to deliver maximal MDI medicine, because in general they deliver twice as much medicine than using an MDI alone does.15,16 (Spacers are not needed for dry powder inhalers due to the difference in their actuation and drug delivery technology.) Also, studies have shown that during an asthma exacerbation, an MDI albuterol with a spacer is equivalent in efficacy and has fewer side effects than nebulized albuterol.17,18
As a general rule, as soon as a child can consistently use a spacer with an oral mouthpiece well, we move the patient from nebulized agents to MDI agents. This allows more rapid and more portable medication delivery. Also spacers reduce albuterol-related tachycardia and tremor and the portion of the inhaled steroid dose that is ingested.
The results of such an approach as we use will be that your patients will be less limited by their asthma. *
Deborah Keye and Robert J. Geller are clinicians at the Pediatric Asthma Center at Hughes Spalding Children’s Hospital of Grady Health System in Atlanta.
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