Part one of a two-part article series discussing the physical therapist’s role in treating asthmatic patients.

Asthma is a major disease in the United States. According to the Centers for Disease Control and Prevention (CDC) figures from a 2002 national survey, 30.8 million people said they had been diagnosed with asthma, with a prevalence of 111 people per 1,000 population.1 People who find out they have asthma are often scared of the diagnosis, have difficulty understanding the disease, and don’t know what they can do to reduce the symptoms. Many of these people need to have access to a health care professional who is knowledgeable and who can take the time needed to assess, advise, and teach. While physicians, nurses, or respiratory therapists may fill this role, physical therapists (PTs) are also being called on to care for and help asthmatics manage their disease, and in some cases may be the only “best” resource around.

Earlier this year, the National Asthma Educator Certification Board confirmed physical therapy’s role in asthma care when it approved PTs to be eligible to take the certification exam to become a Certified Asthma Educator (AE-C) based on holding the PT credential.2 Prior to this approval, PTs had to have a minimum of 1,000 hours’ experience in providing asthma education, counseling, or coordination of services to be eligible to take the AE-C credentialing exam. With the growing need for trained asthma professionals, and with asthma education being a billable service under Medicaid and Medicare, it makes sense for PTs to learn about this disease, obtain the credential, and begin offering this service. Keeping that in mind, in this article we will review the disease to provide a foundation for working with asthmatics. Then, in the next issue, we will have a follow-up article with tips for taking the AE-C exam.

If you are interested in obtaining the AE-C credential, here are two suggestions: 1) be sure to keep this article (it will be referred to again in the follow-up article); and 2) Visit the the National Heart, Lung, and Blood Institute’s Web site and print out the National Asthma Education and Prevention Program (NAEPP) Guidelines. (See reference 3 for details.) This is a large document to download and print, but it thoroughly covers the topic of asthma and will serve as an excellent resource to study for the AE-C exam.

What is Asthma?

Asthma is best described by just a few words: chronic inflammation, hyper-responsive airways, and preventable (or reversible). Chronic inflammation in the airways is associated with several different cells and cellular mediators that cause the airways to thicken and become narrowed, increase the hyper-responsiveness of the smooth muscles surrounding the airways, and increase mucus production. The cells include mast cells, macrophages, T cells, B cells, neutrophils, and eosinophils. These cells release cellular mediators, which include histamine, leukotrienes, cytokines, IL-5, IL-8, and chemokines. The cells are activated by various precipitating factors (also called triggers) that stimulate the development of inflammation. Inflammation is always present, but it can be reduced and controlled with proper medication.3

Exposure to the triggers also causes rapid constriction of the smooth muscles surrounding the airway (called bronchospasm), which greatly restricts airflow, especially on exhalation. This is referred to as hyper-responsive airways, or “twitchy” airways. These two problems—inflammation and bronchospasm—cause airflow obstruction; the patient can breath in but has difficulty breathing out. Asthma is preventable or reversible if the right medications are prescribed and used correctly by the patient, and if the patient is diligent to avoid or reduce exposure to the triggers. (See Table 1 below for a list of the common triggers.)

Asthma is associated with family history, and it may develop in childhood, or later in life as an adult. Atopy is the term used to describe the genetic predisposition for a hypersensitive allergic response—hay fever is a common atopic inherited allergy. Childhood asthma is often associated with atopy (sometimes called atopic or extrinsic asthma), whereas adult asthma does not appear to have a genetic link. Asthma often appears in children as they exercise. This type of associated disease is called exercise-induced asthma.4 Occupational exposure to allergens or irritants is also linked to the development of asthma, and a change in occupation (or a reduction in the allergen or irritant) often reduces or eliminates symptoms of occupational asthma.3

Signs and Symptoms, Diagnostic Testing

There are five key indicators for diagnosing asthma. They include:

a) expiratory wheezing during ausculta- tion of the chest;

b) any history of cough, recurrent wheeze, recurrent difficulty in breath- ing, or recurrent chest tightness;

c) reversible airflow limitation or daily variation in peak flow, as measured by a peak flow meter;

d) symptoms worsen when exposed to precipitating factors or triggers; and

e) symptoms occur or worsen at night, disturbing sleep.

If any of these indicators are present, a pulmonary function test—spirometry—needs to be performed to establish a diagnosis. The key measurements for spirometry include the forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and the ratio of these two (FEV1/FVC). These should be measured before and after taking a short-acting bronchodilator. The FEV1 and the FVC values are compared to reference or predicted values (a comparison called “percent predicted”). Airflow obstruction is present when the prebronchodilator FEV1 is less than 80% predicted and the FEV1/FVC is below the predicted value. When comparing prebronchodilator to postbronchodilator spirometry, a significant response to the bronchodilator is measured in the percent change in the FEV1. This is calculated by subtracting the “pre” FEV1 by the “post” FEV1, dividing this by the “post” FEV1, and multiplying by 100 to give the percent change. If the measured FEV1 increases by at least 200 mL and the percent change is 12% or more, then this is a significant response to the bronchodilator. See the NAEPP Guidelines for a more complete explanation of spirometry (look under “pulmonary function testing”).3

Some patients do not have a known trigger or precipitating factor and have what is called “cough variant asthma.” The only complaint is a chronic cough that may be productive or nonproductive, and often is more problematic at night when it disturbs sleep. Treatment is the same for this type of asthma as the classical cases of asthma.5 Diagnosis of asthma is accomplished by obtaining a detailed medical history, a careful physical examination, and spirometry tests. Severe asthma attacks may result in dangerously low oxygen levels (hypoxemia) and dangerously high carbon dioxide levels (hypercapnia), and they can be fatal despite aggressive treatment.

Classification of Severity, Treatment, and Educational Guidelines

Severity is classified as Step 1–4 based on objective criteria, and the classification is linked to whichever criteria reflects the worst condition. The criteria include days and nights with symptoms (including wheezing, coughing, chest tightness, and difficulty breathing), FEV1, and peak flow meter variability from early morning to afternoon. See Table 2 (page 38) for the classification of severity plus treatment and educational guidelines. The most severe clinical feature will set the level of asthma severity. The level of severity may change to a higher or lower level as indicated by a change in symptoms. (Patients under 5 years old have slightly different classification criteria and different medication dosages.)

For example, a patient who complains of symptoms on 3 days and 2 nights of the week, and has a FEV1 that is 83% predicted, would be classified as having moderate persistent asthma due to the nighttime symptoms. He or she would need to follow the medication guidelines and receive the educational activities for step 3 (see Table 2). If the nighttime symptoms improved—they occurred only 3 to 4 times per month but less than once per week—with all else being the same, the patient would be reclassified as having mild persistent asthma. Improved symptoms and reduced classification would result in changes in the medications (for example dropping from a medium dose inhaled corticosteroid to a low dose and/or dropping the long-acting bronchodilator). See the NAEPP Guidelines.3

Asthma Medications and Delivery Devices

Asthma medications fall into two major categories: long-term control and quick-relief. The long-term-control medications include corticosteroids, nonsteroid anti-inflammatory medications, long-acting beta2-agonists (also called long-acting bronchodilators), theophylline, and leukotriene modifiers. Corticosteroids are taken as inhaled medication on a long-term basis or are taken systemically by oral or intravenous routes, usually on a short-term basis. These are potent anti-inflammatory medications, and are the drugs of choice for reducing inflammation and asthma symptoms. As described in the NAEPP Guidelines, there are five inhaled corticosteroids that come in different inhalers and different strengths. There are three different systemic corticosteroids that are used to fight inflammation, but they are usually given on a temporary basis due to the side effects associated with long-term use. Quick-relief medications include four different inhaled short-acting beta2-agonists, one inhaled anticholinergic, and the same three systemic corticosteroids listed in the long-term-controller category.

Delivery devices for the inhaled medications include metered-dose inhalers (MDIs), dry-powder inhalers (DPIs), or nebulizers that are powered by portable air compressors in the home and/or by compressed gases (such as air or oxygen) in the hospital. It is recommended that MDIs be administered with a spacer/holding chamber to increase delivery to the lungs and reduce technique errors. Patients under 5 years old may require special adaptations or techniques for delivering the inhaled medications.

Asthma is a serious disease that affects many people. Managing the disease correctly takes cooperation and commitment from the patient, their family, and skilled, knowledgeable health care providers. Obtaining the AE-C credential is an excellent way for PTs to obtain the knowledge and understanding needed to work with asthma patients. This article presented a quick overview of asthma; and in next month’s issue, we’ll look at tips for taking the AE-C credentialing exam.

William C. Pruitt is a full-time instructor in the department of Cardiorespiratory Sciences at the University of South Alabama in Mobile, Ala, and a PRN respiratory therapist at Springhill Medical Center in Mobile. He is a registered respiratory therapist, a certified asthma educator, and a certified pulmonary function technologist. He can be reached at wpruitt@jaguar1.usouthal.edu.

References

1. CDC’s National Center for Health Statistics. Asthma prevalence, health care use and mortality. Available at: http://www.cdc.gov/nchs/products/pubs/pubd/hestats/asthma/asthma.htm Accessed July 7, 2005.

2. National Asthma Educator Certification Board. Available at: http://www.naecb.org/index.asp Accessed July 7, 2005.

3. National Asthma Education and Prevention Program Guidelines from the National Heart, Lung, and Blood Institute. Available at: http://www.nhlbi.nih.gov/guidelines/index.htm#asthma Accessed July 7, 2005.

4. Wells, CL. Pulmonary pathology. In: DeTurk WE, and Cahalin LP. Cardiovascular and Pulmonary Physical Therapy. New York: McGraw-Hill; 2004:151–188.

5. Irwin RS, Boulet L-P, Cloutier MM, et al. Managing cough as a defense mechanism and as a symptom: a consensus panel report of the American College of Chest Physicians. Chest. 1998;114(suppl):133S–181S.