Approved by the Missouri Society for Respiratory Care for 1 CRCE
Authored by: Dana L. Evans, MHS, RRT-NPS, AE-C

Learning Objectives:

1. Review the etiology and pathophysiology of pediatric asthma
2. Identify common environmental triggers of asthma.
3. Identify methods to reduce the presence of asthma triggers in the home.
4. Review pharmacology and management of pediatric asthma.

Definition of Asthma:
Asthma is a chronic inflammatory disease of the airways. "Airway inflammation contributes to airway hyper-responsiveness, airflow limitation, respiratory symptoms and disease chronicity. Airway inflammation also contributes to several forms of airflow limitation, including acute bronchoconstriction, airway edema, mucous plug formation, and airway wall remodeling." (1)

Magnitude of the Problem:

• Asthma is the leading chronic illness in children. (2)
• An estimated 20 million Americans suffer from asthma, 5 million of which are children. 50% of all asthma is considered "allergic asthma", also referred to as extrinsic asthma. (3)
• The prevalence of asthma is on the rise, with the greatest increase in diagnosis seen in children under age 5.
• Asthma is the leading cause of school absenteeism, accounting for nearly 14 million school absences each year. (4)
• The cost of treating pediatric asthma is nearly 2 billion dollars each year, with an addition 1 billion dollars in lost wages (due to parents missing work to care for an ill child). (5)
• There are more than 5,000 deaths each year from asthma. Asthma is listed as a contributing factor in an addition 7,000 deaths each year. (6) Despite "better" medications and "better" treatments!

Asthma Capitals - 2006:

The following are considered the worst places to live in the United States if you suffer from asthma and allergies:

1. Scranton, Pennsylvania
2. Richmond, Virginia
3. Philadelphia, Pennsylvania
4. Atlanta, Georgia
5. Milwaukee, Wisconsin
6. Cleveland, Ohio
7. Greensboro, North Carolina
8. Youngstown, Ohio
9. St. Louis, Missouri
10. Detroit, Michigan

Rankings are based on prevalence, risk factors and medical factors. A complete list of "asthma capitals" can be found on the Asthma and Allergy Foundation website.

Etiology of Asthma:
The exact etiology of asthma remains unknown. Research into this subject has found links between the diagnosis of asthma and genetic predisposition, sex, race, socioeconomic status and environmental exposures.

Pathophysiology of Extrinsic Asthma:

• Stimulus (exposure to the trigger) causes the formation of antibodies (IgE). Patients may not exhibit a reaction to the trigger until the second exposure due to the formation of these antibodies!
• Re-exposure causes mast cells to rupture. This causes the release of many chemical mediators, (histamine, leukotrienes, eosinophils) leading to bronchospasm.
• This then allows the release of other mediators that begin an inflammatory response of the airways and increase the secretion production (increase in goblet cells and mucus production, leads to mucus plugging).

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Asthma Triggers:

Allergens vs. Irritants:

Allergens are IgE mediated, they affect only those individuals who are sensitized. Allergens are not dose dependent (individuals who are sensitized to the trigger will be affected, regardless of the amount they are exposed to).

Irritants are not IgE mediated, they will affect EVERYONE if the dose is high enough (every individual will experience symptoms if the exposure to the irritant is high enough).

Dust mites -
Dust Mites are microscopic relatives of the spider. They cannot be seen by the naked eye. Dust mites can be found in EVERY home. The body parts and feces of a dust mite may elicit an allergic response in those sensitized to this allergen. It has been noted that a single dust mite can produce 200 times its own weight in fecal material. (7)

A dust mites' primary food source is human and animal skin cells. They can be found in mattresses, pillows, carpets, upholstered furniture, clothes and stuffed toys.

How to avoid this trigger:

• Cover mattresses and pillows with dust proof ("allergen-impermeable") zippered covers.
• Wash bedding (sheets, blankets and bedcovers) once per week in hot water.
• Purchase only washable stuffed toys, wash them weekly in hot water and dry them completely. Do not keep stuffed toys on beds.
• If possible, remove carpets from the bedrooms.

Cockroaches -
Cockroaches produce a protein that can be found in their feces and urine. This protein may elicit an allergic response in those sensitized to this allergen. Cockroaches can be found most commonly in urban areas and in the southern portion of the United States. (7)

How to avoid this trigger:

• Limit the amount of food left around the house.
• Keep food in sealed containers.
• Wash dishes as soon as you are done with them.
• Scrub kitchen countertops and floors at least once a week.
• Pesticide Sprays may be effective in removing cockroaches from a home. However, if the patient lives in an apartment complex the entire building must be treated in order for the spray to be effective. Should the parent decide to utilize a spray for the treatment of their home, one must remove the asthmatic child from the area, assure that spraying only occurs in the area of infestation and make sure that the treated area is thoroughly aired out before the child returns.

Furred Animals -
Warm blooded pets secrete a protein in their oil glands, saliva, urine, skin flakes and hair. It is this protein that will elicit an allergic response in the asthmatic patient. (7)

How to avoid this trigger:

• If possible, remove pet from inside the home. If this is not a possibility, advise the patient to keep the pet out of their bedroom and keep the door closed. Since most of our time is spent in our bedroom, keeping animal dander out of this room is essential.
• Keep the pet off of upholstered furniture.
• Wash hands and change clothes after contact with the pet.
• Wash pet weekly.
• Avoid contact with soiled litter boxes.
• Vacuum and dust with a damp cloth regularly. People with asthma should not be present during vacuuming.

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Pharmacology:
Controller medications:

• Corticosteroids
• • Pulmicort ® , Azmacort ® , Flovent ® , etc.
  • Airway inflammation has been shown to lead to airway remodeling. Treatment with corticosteroids is considered a key component of asthma management in both children and adults.
• Long-acting beta agonists
• • Serevent ® , Foradil ® , etc.
• Cromolyn/nedocromil
• • These medications interrupt the inflammatory response to allergic stimuli and could be considered as alternatives to corticosteroid treatments (although steroids have been shown to be the MOST effective for long term control of asthma).
• Leukotriene modifiers
• • Accolate ® , Singulair ® , Zyflo ® , etc.
  • These medications block the inflammatory effect of leukotrienes.
• Xolair ®
• • Blocks the release of IgE

Quick-Relief medications:

• Short-acting beta2-agonists
• Anticholinergics (Check for soy/peanut allergy before administering an anticholinergic medication)

Asthma Management:
The following recommendations for asthma management can be found in the National Asthma Education Prevention Programs Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma - Update on Selected Topics, 2002. (8)

Stepwise approach to asthma management:

• Step 1 - Mild Intermittent Asthma
• Step 2 - Mild Persistent Asthma
• Step 3 - Moderate Persistent Asthma
• Step 4 - Severe Persistent Asthma

Treatment recommendations based on asthma classification:

Adults and Children greater than 5 years of age:

• Mild Intermittent
  • No daily medications needed
• Mild Persistent
• • Low dose inhaled corticosteroids
• Moderate Persistent
• • Low/medium dose inhaled corticosteroids AND
  • Long acting beta agonist
• Severe Persistent
• • High dose inhaled corticosteroids AND
  • Long acting beta agonist

*All patients should have a quick relief medication available as needed.

Infants and Children less than 5 years of age:

• Mild Intermittent
• • No daily medications needed
• Mild Persistent
• • Low dose inhaled corticosteroids
• Moderate Persistent
• • Low dose inhaled corticosteroid and long acting beta agonist OR
  • Medium dose inhaled corticosteroid
• Severe Persistent
• • High dose inhaled corticosteroid AND
  • Long acting beta agonist

*All patients should have a quick relief medication available as needed.

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High Risk Asthma:
Patients classified as having "high risk asthma" are likely to suffer a fatal event related to their asthma. The following are indicators that a patient may be high risk.

• History of intubation for asthma
• History of an ICU stay for asthma
• 2 or more hospitalizations for asthma in the past year
• 3 or more ED visits for asthma in the past year
• Use of 2 or more canisters of short acting beta agonist in the past month
• Hospitalization or ED visit for asthma in the past month
• Current use of systemic corticosteroids to manage asthma symptoms
• "Poor perceiver" of airflow limitation - poor perceivers are those who cannot recognize their asthma symptoms
• Low socioeconomic status
• Sensitivity to Alternaria. Alternaria is a mold that can be found on organic debris. The relationship between alternaria sensitivity and high risk asthma is unknown.

References:

1. National Asthma Education Prevention Program. Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. National Institutes of Health, 1997
2. Chronic Conditions: A Challenge for the 21^st Century. National Academy on an Aging Society, 2000
3. Asthma at a Glance. National Center for Environmental Health (NCEH), U.S. CDC, 1999
4. The Costs of Asthma. Asthma and Allergy foundation of America , 2000
5. Pediatric Asthma: Promoting best practices - Guide for managing Asthma in Children. American Academy of Allergy , Asthma and Immunology, 2002.
6. New Asthma Estimates: Tracking Prevalence, Health Care and Mortality. NCHS, CDC, 2001
7. Asthma and Indoor Environments. www.epa.gov/asthma
8. Asthma Education Prevention Programs Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma - Update on Selected Topics. National Institutes of Health, 2002.

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