Asthma Overview

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Asthma Overview

What do each of these individuals have in common: First, an eighteen-year-old suddenly develops wheezing and shortness of breath when visiting his grandmother who happens to have a cat. Second, a thirty year old woman has colds that "always go into her chest," causing coughing and difficulty breathing. Lastly, a sixty- year-old man develops shortness of breath with only slight exertion even though he has never smoked. The answer is that they all may have asthma.
These are some of the many faces of asthma. Most researchers believe that the different patterns of asthma are all related to one condition. Other researchers feel that separate lung conditions exist. There is currently no cure for asthma and no single exact cause has been identified. Therefore, understanding the changes that occur in asthma, how it makes you feel, and how it can behave over time is vital. This knowledge empowers you to take an active role in your own health care.

Myths about asthma
Before we present the typical symptoms of asthma, we should dispel some common myths about this condition. This is best achieved by conducting a short true or false quiz.

T or F Asthma is "all in the mind."
T or F You will "grow out of it."
T or F Asthma can be cured, so it is not serious and nobody dies from it.
T or F You are likely to develop asthma if someone in your family has it.
T or F You can "catch" asthma from someone else who has it.
T or F Moving to a different location, such as the desert, can cure asthma.
T or F People with asthma should not exercise.
T or F Asthma does not require medical treatment.
T or F Medications used to treat asthma are habit-forming.
T or F Someone with asthma can provoke episodes anytime they want in order to get attention.

Here are the answers:

F - Asthma is not a psychological condition. However, emotional triggers can cause flare-ups.
F - You cannot outgrow asthma. In about 50% of children with asthma, the condition may become inactive in the teenage years. The symptoms, however, may reoccur at anytime in adulthood.
F - There is no cure for asthma, but the disease can be controlled in most patients with good medical care. The condition should be taken seriously since uncontrolled asthma may result in emergency hospitalization and possible death.
T - You have a 6% chance of having asthma if neither parent has the condition; a 30% chance if one parent has it; and a 70% chance if both parents have it.
F - Asthma is not contagious.
F - A new environment may temporarily improve asthma symptoms, but it will not cure asthma. After a few years in the new location, many persons become sensitized to the new environment and the asthma symptoms return with the same or even greater intensity than before.
F - Swimming is an optimal exercise for those with asthma. On the other hand, exercising in dry, cold air, may be a trigger for asthma in some people.
F - Asthma is best controlled by having an asthma management plan designed by your doctor that includes the medications used for quick relief and those used as controllers.
F - Asthma medications are not addictive.
F - Asthma attacks cannot be faked.

What is asthma?
Asthma is a chronic inflammation of the bronchial tubes (airways) that causes swelling and narrowing (constriction) of the airways. The result is difficulty breathing. The bronchial narrowing is usually either totally or at least partially reversible with treatments.

Bronchial tubes that are chronically inflamed may become overly sensitive to allergens (specific triggers) or irritants (non-specific triggers). The airways may become "twitchy" and remain in a state of heightened sensitivity. This is called "Bronchial Hyperreactivity" (BHR). It is likely that there is a spectrum of bronchial hyperreactivity in all individuals. However, it is clear that asthmatics and allergic individuals (without apparent asthma) have a greater degree of bronchial hyperreactivity than non-asthmatic and non-allergic people. In sensitive individuals, the bronchial tubes are more likely to swell and constrict when exposed to triggers such as allergens, tobacco smoke, or exercise. Amongst asthmatics, some may have mild BHR and no symptoms while others may have severe BHR and chronic symptoms.

Allergy Assist
Asthma affects people differently. Each individual is unique in their degree of reactivity to environmental triggers. This naturally influences the type and dose of medication prescribed, which may vary from one individual to another.

From the past to the present
Physicians in ancient Greece used the word "asthma" to describe breathlessness or gasping. They believed that asthma was derived from internal imbalances, which could be restored by healthy diet, plant and animal remedies, or lifestyle changes.

Allergy Jargon
Asthma is derived from the Greek word "Panos," meaning panting.
Chinese healers understood that "xiao-chiran," or "wheezy breathing," was a sign of imbalance in the life force they called "Qi." They restored "Qi" by means of herbs, acupuncture, massage, diet, and exercise.
The Hindu philosophers connected the soul and breath as part of the mind, body, and spirit connection. Yoga uses control of breathing to enhance meditation. Indian physicians taught these breathing techniques to help manage asthma.
Allergy Fact
Maimonides was a renowned twelfth century rabbi and physician who practiced in the court of the sultan of Egypt. He recommended to one of the Royal Princes with asthma that he eat, drink, and sleep less. He also advised that he engage in less sexual activity, avoid the polluted city environment, and eat a specific remedy - chicken soup.

The balance of the "four humors," which was derived from the Greco-Roman times, influenced European medicine until the middle of the eighteenth century. In a healthy person, the four humors, or bodily fluids - blood, black bile, yellow bile, and phlegm - were in balance. An excess of one of these humors determined what kinds of disorders were present. Asthmatics who were noted for their coughing, congestion, and excess mucus (phlegm) production were therefore regarded as "phlegmatic."
By the 1800's, aided by the invention of the stethoscope, physicians began to recognize asthma as a specific disease. However, patients still requested the traditional treatments of the day, such as bloodletting, herbs and smoking tobacco. These methods were used for a variety of conditions, including asthma. Of the many remedies that were advertised for asthma throughout the nineteenth century, none were particularly helpful.

Allergy Fact
As early as 1892, the famous Canadian-American physician, Sir William Osler, suggested that inflammation played an important role in asthma.

Bronchial dilators first appeared in the 1930's and were improved in the 1950's. Shortly thereafter, corticosteroid drugs that treated inflammation appeared and have become the mainstay of therapy used today.

The scope of the problem
Asthma is now the most common chronic illness in children, affecting 1 in every 15. Five percent of adults in North America are also afflicted. In all, there are about 1 million Canadians and 15 million Americans who suffer from this disease.
The number of new cases and the yearly rate of hospitalization for asthma have increased about 30% over the past 20 years. Even with advances in treatment, asthma deaths among young people have more that doubled.

Allergy Fact
There are about 5,000 deaths annually from asthma in the U.S. and about 500 deaths per year in Canada.

Normal bronchial tubes
Before we can appreciate how asthma affects the bronchial airways, we should first take a quick look at the structure and function of normal bronchial tubes.

The air we breathe in through our nose and mouth passes through the vocal cords (larynx) and into the windpipe (trachea). The air then enters the lungs by way of two large air passages (bronchi), one for each lung. The bronchi divide within each lung into smaller and smaller air tubes (bronchioles), just like branches of an inverted tree. Inhaled air is brought through these airways to the millions of tiny air sacs (alveoli) that are contained in the lungs. Oxygen (O2) passes from the air sacs into the blood stream through numerous tiny blood vessels called capillaries. Similarly, the body's waste product, carbon dioxide (CO2), is returned to the air sacs and then eliminated upon each exhalation.

Normal bronchial tubes allow rapid passage of air in and out of the lungs to ensure that the levels of O2 and CO2 remain constant in the blood stream. The outer walls of the bronchial tubes are surrounded by smooth muscles that contract and relax automatically with each breath. This allows the required amount of air to enter and exit the lungs to achieve this normal exchange of O2 and CO2. The contraction and relaxation of the bronchial smooth muscles are controlled by two different nervous systems that work in harmony to keep the airways open.

The inner lining of the bronchial tubes, called the bronchial mucosa, contains: (1) mucus glands that produce just enough mucus to properly lubricate the airways; and (2) a variety of so called inflammatory cells, such as eosinophils, lymphocytes, and mast cells. These cells are designed to protect the bronchial mucosa from the inhaled microorganisms, allergens, and irritants we inhale, and which can cause the bronchial tissue to swell. Remember, however, that these inflammatory cells are also important players in the allergic reaction. Therefore, the presence of these cells in the bronchial tubes causes them to be a prime target for allergic inflammation.

How does asthma affect breathing?
Asthma causes a narrowing of the breathing airways, which interferes with the normal movement of air in and out of the lungs. Asthma involves only the bronchial tubes and does not affect the air sacs or the lung tissue. The narrowing that occurs in asthma is caused by three major factors; inflammation, bronchospasm, and hyper-reactivity.

Inflammation
The first and most important factor causing narrowing of the bronchial tubes is inflammation. The bronchial tubes become red, irritated, and swollen. The inflammation occurs in response to an allergen or irritant and results from the action of chemical mediators (histamine, leukotrienes, and others). The inflamed tissues produce an excess amount of "sticky" mucus into the tubes. The mucus can clump together and form "plugs" that can clog the smaller airways. Eosinophils and other cells, which accumulate at the site, cause tissue damage. These damaged cells are shed into the airways, thereby contributing to the narrowing.

Bronchospasm
The muscles around the bronchial tubes tighten during an attack of asthma. This muscle constriction of the airways is called bronchospasm. Bronchospasm causes the airway to narrow further. Chemical mediators and nerves in the bronchial tubes cause the muscles to constrict.

Hyper-reactivity (Hypersensitivity)
In patients with asthma, the chronically inflamed and constricted airways become highly sensitive, or reactive, to triggers such as allergens, irritants, and infections. Exposure to these triggers may result in progressively more inflammation and narrowing.

The combination of these three factors results in difficulty with breathing out, or exhaling. As a result, the air needs to be forcefully exhaled to overcome the narrowing, thereby causing the typical "wheezing" sound. People with asthma also frequently "cough" in an attempt to expel the thick mucus plugs. Reducing the flow of air may result in less oxygen passing into the blood stream and if very severe, carbon dioxide may dangerously accumulate in the blood.

The importance of inflammation
Inflammation, or swelling, is a normal response of the body to injury or infection. The bloodflow increases to the affected site and cells rush in and ward off the offending problem. The healing process has begun. Usually, when the healing is complete, the inflammation subsides. Sometimes, the healing process causes scarring. The central issue in asthma, however, is that the inflammation does not resolve completely on its own. In the short term, this results in recurrent "attacks" of asthma. In the long term, it may lead to permanent thickening of the bronchial walls, called airway "remodeling." If this occurs, the narrowing of the bronchial tubes may become irreversible and poorly responsive to medications. Therefore, the goals of asthma treatment are: (1) in the short term, to control airway inflammation in order to reduce the reactivity of the airways; and (2) in the long term, to prevent airway remodeling.

Allergy Assist
The hallmark of managing asthma is the prevention and treatment of airway inflammation. It is also likely that control of the inflammation will prevent airway remodeling and thereby prevent permanent loss of lung function.

Figure I illustrates how important events in the asthma cycle are linked. Various triggers in susceptible individuals result in airway inflammation. Prolonged inflammation induces a state of airway hyper-reactivity, which might progress to airway remodeling unless treated effectively.

Asthma triggers
Asthma symptoms may be activated or aggravated by many agents. Not all asthmatics react to the same triggers. Additionally, the effect that each trigger has on the lungs varies from one individual to another. In general, the severity of your asthma depends on how many agents activate your symptoms and how sensitive your lungs are to them. Most of these triggers can also worsen nasal or eye symptoms.
Triggers fall into two categories:

Allergens ("specific")
Non-allergens - mostly irritants (non-"specific")

Once your bronchial tubes (nose and eyes) become inflamed from an allergic exposure, a re-exposure to the offending allergens will often activate symptoms. These "reactive" bronchial tubes might also respond to other triggers, such as exercise, infections, and other irritants. The following is a simple checklist.

Common Asthma Triggers:
Allergens

"Seasonal" pollens.
Year-round dust mites, molds, pets, and insect parts.
Foods, such as fish, egg, peanuts, nuts, cow's milk, and soy.
Additives, such as sulfites.
Work-related agents, such as latex.

Allergy Fact
About 80% of children and 50% of adults with asthma also have allergies.

Irritants

Respiratory infections, such as those caused by viral "colds," bronchitis, and sinusitis.
Drugs, such as aspirin, other NSAIDs (nonsteroidal anti-inflammatory drugs), and Beta Blockers (used to treat blood pressure and other heart conditions).
Tobacco smoke.
Outdoor factors, such as smog, weather changes, and diesel fumes.
Indoor factors, such as paint, detergents, deodorants, chemicals, and perfumes.
Nighttime.
GERD (gastro-esophageal reflux disorder).
Exercise, especially under cold dry conditions.
Work-related factors, such as chemicals, dusts, gases, and metals.
Emotional factors, such as laughing, crying, yelling, and distress.
Hormonal factors, such as in premenstrual syndrome.

The many faces of asthma - "Expected"
The many potential triggers of asthma largely explain the different ways in which asthma can present. In most cases, the disease starts in early childhood - age 2 to 6 years. In this age group, the cause of asthma is often linked to exposure to allergens, such as dust mites and tobacco smoke, and viral respiratory infections. In very young children, less than 2 years of age, asthma can be difficult to diagnose with certainty. Wheezing at this age often follows a viral infection and might disappear later, without ever leading to asthma. Asthma, however, can develop again in adulthood. Adult onset asthma occurs more often in women, mostly middle-aged, and frequently follow a respiratory tract infection. The triggers in this group are usually non-allergic in nature.

Allergic (Extrinsic) and non-allergic (Intrinsic) asthma
Your doctor may refer to asthma as being "extrinsic" or "intrinsic." A better understanding of the nature of asthma can help explain the differences between them. Extrinsic, or allergic asthma, is more common (90% of all cases) and typically develops in childhood. Eighty percent of children with asthma also have documented allergies. Typically, there is a family history of allergies. Additionally, other allergic conditions, such as hay fever or eczema, are often also present. Allergic asthma often goes into remission in early adulthood. However, in 75% of cases, the asthma reappears later.

Intrinsic asthma represents about 10% of all cases. It usually develops after the age of 30 and is not typically associated with allergies. Women are more frequently involved and many cases seem to follow a respiratory tract infection. The condition can be difficult to treat and symptoms are often chronic and year-round.