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Asthma For Dummies
By William E. Berger
John Wiley & Sons ISBN: 0-7645-4233-8
Chapter One Knowing What's Ailing You
In This Chapter
* Connecting asthma and allergies
* Making sense of asthma signs and symptoms
* Defining the spectrum of asthma
* Determining how to properly manage asthma
According to many experts, asthma is now a global epidemic, and its prevalence and severity continue to grow in many parts of the world, primarily in highly developed countries, including the United States, Western Europe, Australia, and New Zealand. More than 17 million people in the United States have some form of asthma. That equals three times the number of asthma cases diagnosed in 1960, despite major medical breakthroughs during the last 40 years in diagnosing and treating airway obstruction - the basis of this disease.
One of the most important factors in this rising incidence of asthma may be an increase of indoor air pollution (see Chapter 2 for more information). In addition, according to a growing number of researchers, asthma's pervasiveness in countries with the most advanced public health systems could also be due to a combination of factors popularly referred to as the hygiene hypothesis. This hypothesis proposes that although modern day hygiene in much of the developed world has greatly reduced the incidence of childhood diseases and dramatically improved the well-being of the overall population, people may still benefit - especially aschildren - from some exposure to key types of bacteria and infections. In other words, a little dirt early in life may be good. The idea is that the human immune system is thereby primed to develop responses mainly against bacterial, viral, and parasitic infections rather than against otherwise innocuous allergens and other substances that trigger most patients' asthma symptoms.
Proponents of the hygiene hypothesis point to lower rates of asthma as well as allergies that afflict many asthma patients - mainly allergic rhinitis (hay fever) and atopic dermatitis (allergic eczema) - in less developed and rural parts of the planet. In those areas, living environments aren't often as hygienic as in the so-called first world, and infectious childhood diseases are more common. Because the hygiene hypothesis is finding increased support among health professionals in North America, Europe, Australia, and New Zealand, and is also a hot topic with most of my patients, I discuss it further in Chapter 6.
Although the mortality rates of other serious illnesses are declining, deaths due to asthma continue to rise. More than 5,000 Americans - many between the ages of 5 and 34 - die each year because of asthma. Most of these deaths, however, are clearly preventable. With proper diagnosis, effective and timely treatment, and an asthma management plan that empowers a person with asthma (and the patient's family) to control symptoms of the disease, most asthma patients can lead fulfilling and productive lives, free from the worry of life-threatening asthma attacks.
Understanding the Relationship between Asthma and Allergies
The vast majority of asthma patients also suffer from certain types of allergic conditions. In fact, a relationship exists between asthma and these allergic ailments, and it's vital for asthmatics, their families, and healthcare providers to understand the connections between, for example, the characteristic coughing and wheezing of asthma, and the sneezing and nasal congestion of a typical hay fever attack.
Asthma denotes a specific disease process of the lungs, while allergy is a descriptive term for a wide variety of hypersensitivity disorders (meaning that you're excessively sensitive to one or more substances to which most people don't normally react). Asthma and allergy share a strong bond, often coexisting as partners in disease. Effectively managing your asthma also requires understanding how an allergic condition may be affecting you. But always remember that asthma is the disease and allergies are one of the main causes.
Symptoms of seemingly disparate ailments such as most cases of asthma, allergic rhinitis, and atopic dermatitis, as well as some food allergies (see Chapter 8), basically result from your immune system's similar, hyperreactive response to otherwise harmless substances that doctors refer to as allergens. Think of asthma and allergy as two distinct avenues with major intersections, like Broadway and 42nd Street or Hollywood and Vine. In order to be an aware and involved patient, you often have to travel down both pathways.
The word allergy is the ancient Greek term for an abnormal response or overreaction. Contrary to popular belief, weak or deficient immune systems don't cause asthma or allergy ailments. Rather, your body's defenses work overtime, making your immune system too sensitive to substances that pose no real threat. That's why physicians often use the term hypersensitivity to refer to an allergy.
These are the main points to keep in mind when dealing with asthma and related allergies that cause it:
These ailments aren't infectious or contagious. You don't catch asthma or an allergy. However, as I explain in "Sensitizing your immune system," later in this chapter, you may inherit a genetic predisposition to develop hypersensitivities that can eventually appear as asthma and/or allergies.
Asthma and allergies aren't like trends or shoe sizes. You don't really outgrow them. Extensive studies over the past 15 years show that although your ailment can certainly vary in character and severity over your lifetime, asthma and allergies are ongoing physical conditions that are most likely always present in some form.
Allergic rhinitis often coexists with asthma and can affect your nose, ears, sinuses, eyes, and throat (see Chapter 7).
Triggers of asthma and allergic rhinitis include allergens, such as pollens, animal dander, dust mites, mold spores, and, for some asthma patients, certain foods and drugs. (See "Sensitizing your immune system," later in this chapter, for more detailed classifications of these items.)
Asthmatic reactions can also result from nonallergic triggers that act as irritants, including tobacco smoke, household cleaners, aerosol products, solvents, chemicals, fumes, gases, paints, smoke, and indoor and outdoor air pollution.
Other forms of nonallergic triggers that primarily affect people with asthma are known as precipitating factors. These factors include
Other medical conditions, such as rhinitis, sinusitis, gastroesophageal reflux disease (GERD), and viral infections (colds, flu) Physical stimuli, such as exercise or variations in both air temperature and humidity levels
Sensitivities to food additives such as sulfites, drugs such as beta-blockers (Inderal, Lopressor, Corgard, Timoptic), and aspirin and related over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin), ketoprofen (Actron, Orudis), naproxen (Aleve), and newer prescription NSAIDs known as COX-2 inhibitors, including celecoxib (Celebrex) and rofecoxib (Vioxx)
When allergies affect the lungs, the resulting coughing, wheezing, and shortness of breath often manifest as symptoms of asthma. However, allergies can also affect other organs of the body at the same time. Therefore, although allergic reactions can trigger symptoms of asthma, they can also simultaneously trigger symptoms of other allergic disorders, such as allergic rhinitis (mainly affecting your nose) and allergic conjunctivitis (your eyes).
All that wheezes, coughs, sneezes, drips, runs, congests, waters, itches, erupts, or swells isn't always due to an allergic reaction. That's why, as I explain in the section "Managing Asthma Effectively," later in this chapter, the first step to receiving effective treatment is to have your ailment properly diagnosed (see Chapter 2 for a full discussion).
Although the majority of people with asthma also have allergies (allergic rhinitis in most cases), some manifestations of asthma seem to develop without an allergic component. In cases of adult-onset asthma, which often develops in people older than 40 and is less common than child-onset asthma, atopy (a genetic tendency toward developing allergic hypersensitivity; see the next section) doesn't appear to play an important role. Instead, precipitating factors such as sinusitis, GERD, nasal polyps, and sensitivities to aspirin and related NSAIDs are more likely to trigger this condition (see Chapter 5).
Triggering Asthma and Allergic Reactions
Your immune system acts as your second line of defense against foreign substances. (The main barrier against foreign substances is your largest organ - your skin. Tuck that away in your brain for your next Trivial Pursuit tournament!) Usually your immune system protects you against infectious bacteria, viruses, parasites, and other harmful agents by producing antibodies that recognize the invaders and fend them off without too much fuss.
In fact, most of the time, as long as your immune system works well, you may not even know that this constant, ongoing process takes place to ensure your survival and good health. However, with an allergic condition, your immune system overproduces antibodies against typically harmless or inoffensive substances such as pollens.
Sensitizing your immune system
A complex sensitization process, in which your immune system responds to allergens, causes allergic reactions that often affect asthma patients. Allergens that your immune system may respond to include the following:
Dander from many animals, including cats, dogs, rabbits, birds, and horses, as well as gerbils and other pet rodents (see Chapters 5 and 10)
Dust mites (see Chapter 10)
Foods, including milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat (see Chapter 8)
Mold spores (see Chapter 10)
Pollens from certain grasses, weeds, and trees (see Chapter 10)
Approximately 10 percent of asthma patients also have sensitivities to aspirin, aspirin-containing compounds (such as Alka-Seltzer, Anacin, and Excedrin), and other NSAIDs.
Developing an allergic reaction
If you're predisposed to developing asthma and/or allergies, here's how a typical sensitization process and allergic reaction can develop, using ragweed pollen, one of the most common triggers of allergic rhinitis, as an example (you can find more details about this process in Chapter 6):
1. Ragweed pollen enters your body, usually as a result of inhaling it through your nose.
2. Your immune system detects the presence of these foreign substances in your body and reacts by producing IgE antibodies, a special class of antibodies.
3. IgE antibodies attach themselves to the surfaces of mast cells that line tissues throughout your body, especially in your nose, eyes, lungs, and skin.
4. Your body designs IgE antibodies to counter specific substances.
Your immune system is a magnificent memory machine: Unlike you or me, it hardly ever forgets a face. After sensitization occurs, you'll likely experience allergies to that substance for most of your life. With ragweed, for example, your immune system produces specific IgE antibodies with receptor sites that allow ragweed allergens to cross-link two of the IgE ragweed-specific antibodies. The IgE antibodies work like a lock on the mast cell surface, and the allergen is the key. When the ragweed allergen connects with two IgE antibodies on the mast cell surface, the union of all three (allergen, antibody, and mast cell) results in the cell releasing its chemical contents.
5. Unlocking the mast cell initiates the secretion of histamine, leukotrienes, and other potent chemical mediators of inflammation as a defensive response to the allergen.
In turn, the actions of these chemicals trigger the swelling and inflammation that result in familiar allergy symptoms.
Doctors frequently use antihistamines to relieve allergy symptoms because histamine plays such an important role in the inflammatory process. In addition, as I explain in Chapters 12 and 15, in the last two decades, government-funded and pharmaceutical researchers have developed more specialized drugs to counter and/or inhibit some of the more fundamental allergic processes. In particular, inhaled corticosteroids, mast cell stabilizers, leukotriene modifiers, and anti-IgE antibodies (see Chapter 15) provide new therapeutic approaches to preventing and controlling symptoms of asthma and other allergic reactions.
Previewing Asthma and Related Conditions
Consider this part of the chapter a preview of coming reactions. In the following sections, I summarize the significant features of the most common types of asthma, as well as hay fever and allergic eczema, and provide important details about distinguishing them from nonallergic conditions that are similar. I also include references to the chapters where I discuss these ailments in more detail.
Asthma: Breathing and wheezing
The most fundamental definition of asthma is a chronic, inflammatory airway disease of the lungs that causes breathing problems. However, in practice, asthma has many faces and is often difficult to recognize and properly diagnose. As a result, even though currently available prescription medications offer effective ways of relieving, preventing, and controlling the symptoms and underlying inflammation (redness, swelling, and congestion that characterize asthma), the disease continues to cause serious problems for many people worldwide.
Inflammation of the airways (bronchial tubes) is the most important underlying factor in asthma. In the vast majority of cases, if you have asthma, your symptoms may come and go, but the underlying inflammation usually persists.
Asthma's characteristic symptoms are
Productive coughs (coughs that produce mucus)
Shortness of breath
Important symptoms of asthma in infancy and early childhood include wheezing, persistent coughing, and recurring or lingering chest colds. (Because of its symptoms, asthma in children is often misdiagnosed as recurring bronchitis, recurring chest colds, or lingering coughs.)
Excerpted from Asthma For Dummies by William E. Berger Excerpted by permission.
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