Asthma in Children

A chronic inflammatory disease of the lungs, asthma consists of the following: symptoms of cough, shortness of breath, wheezing, and chest tightness that can occur episodically, usually triggered by a specific environmental factor; narrowing of the airways that can be completely or partially reversible; and increased reaction to specific stimuli. Childhood asthma costs society an enormous amount, including 10 million missed school days, which in turn causes lost productivity due to parents’ missed work days, and $1.6 billion annually for treatment.

The most common chronic childhood disease, asthma affects over five million U.S. children. From 1980 to 1996, asthma prevalence in the general U.S. population has increased more than 50 percent, with the largest increase reported in the younger-than-18 age group. In 2003, the Centers for Disease Control and Prevention found that lifetime asthma prevalence among children younger than 18 was 12.5 percent with a current asthma prevalence of 8.5 percent in this same age group.

The increase in childhood asthma prevalence may be explained by several theories. One theory suggests that improved hygiene and a concomitant decrease in exposure to infectious pathogens have caused an imbalance in the normal immune response in children. It has also been suggested that an increase in indoor air pollution and an increase in exposure to indoor allergens (e.g., cockroaches, cats, dust mites, dogs, and molds) has led to more diagnoses of childhood asthma. Other explanations include early exposure to respiratory viral infections, enhanced host susceptibility (i.e., more premature infants surviving with chronic lung diseases), and a general increase in knowledge about asthma, both within the general population and the medical community, leading to more diagnoses of childhood asthma.

Risk factors for developing childhood asthma include the following: living in an urban environment, race, socioeconomic status, increased exposure to allergens, and smoking.

Childhood asthma symptoms occur due to airflow obstruction when smooth muscles in the airways constrict in response to an inciting agent. Airway wall edema, accumulation of mucus in the airways, and the body's inflammatory response also contribute to asthma symptoms. Reduced expiratory airflow occurs due to airflow obstruction. This can be diagnosed using pulmonary function tests. Additionally, if the obstruction is reversed after the patient is given a bronchodilator, then one can feel fairly certain of an asthma diagnosis.

Airway hyperresponsiveness is another characteristic of asthma. This is defined as the degree to which the airways narrow in response to a nonspecific stimulus like methacholine, a drug used to induce bronchoconstriction; cold air; or histamine. Asthmatic children's airways react to a lower dose of methacholine than those without asthma due to the hyperresponsivenss of their airways. Environmental allergens, viral upper respiratory infections, and air pollutants can also induce hyperresponsive airways. The degree of increased airway responsiveness correlates well with asthma severity in children. Last, chronic airway inflammation causes changes in the lungs at the onset of asthma symptoms, including the accumulation of an abundance of inflammatory cells such as eosinophils, lymphocytes, and mast cells.

Mainstays of asthma treatment include short- and long-acting bronchodilators, inhaled and oral corticosteroids, and environmental control practices. Environmental control practices are defined as behavioral changes and practices to reduce symptoms and complications of asthma, including pet removal, cockroach extermination, frequent vacuuming, and other methods.

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