Asthma : (noun)
1: respiratory disorder characterized by wheezing; usually of
allergic origin [syn: asthma attack, bronchial asthma]
Based on WordNet 2.0
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Asthma : \Asth"ma\ (?; 277), n. [Gr. ? short-drawn breath, fr. ?
to blow, for ?: cf. Skr. v[=a], Goth. waian, to blow, E.
wind.] (Med.)
A disease, characterized by difficulty of breathing (due to a
spasmodic contraction of the bronchi), recurring at
intervals, accompanied with a wheezing sound, a sense of
constriction in the chest, a cough, and expectoration.
Based on Webster's Revised Unabridged Dictionary
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Asthma : parenchyma of the lung) itself.
spasm (bronchospasm), and hyperreactivity (over-reaction of the bronchi to factors that can precipitate asthma).
The incidence of asthma has risen dramatically in the past 20 years, a period far too short to reflect any significant changes in the gene pool. This supports the important role that environmental
influences (allergy, infection, lifestyle, and diet) have on the development of asthma.
A genetic role in asthma has long been suspected, primarily due to the clustering of cases within families and the concordance for asthma in identical twins. Several studies conclude that heredity
increases ones chances of developing asthma, particularly if allergies or other allergic conditions are present. Moreover, one may pass this tendency to asthma to the next generation. So, what are the
chances that a child will develop asthma? - 6.5% of families in which neither parent has asthma have a child with asthma.
- 28% of families in which one parent has asthma have a child with
asthma.
- 63% of families in which both parents have asthma have at least one child with asthma.
In other words, when compared with children whose parents do not have asthma, children with 1
parent who has asthma are 3-6 times more likely to develop the condition and children with 2 parents with asthma are 10 times more at risk. Certainly, identical twins are more likely to share allergies
and asthma than are non-identical (fraternal) twins.
A hunt lasting a decade and spanning two continents led in 2004 to the finding of two asthma genes on chromosome 7p. A candidate gene was found encoding a G protein-coupled receptor named GPRA (G
protein-coupled receptor for asthma susceptibility). GPRA appears involved in the susceptibility to allergy and asthma.
Inheriting genes for asthma does not necessarily mean that a person will definitely develop asthma. The genes make for susceptibility. The susceptibility genes together with the asthma-promoting
factors in your environment, and your lifestyle can all conspire to put you at risk for developing asthma. As such, your genetic make-up is only one piece of the puzzle.
Many environmental factors are known to precipitate attacks of asthma. These factors are all either allergens or irritants. Allergic factors play a role in many, but by no means every, case of
asthma.
Signs and symptoms include shortness of breath, chest tightness, breathing tests. Chest X-rays are usually normal in people with asthma.
As a rule, the bronchial narrowing characteristic of asthma can be partially or completely prevented or reversed with proper treatment. Avoiding precipitating factors is important in managing
asthma.
Based on University of Miami School of Medicine [Medical_Dictionary]:
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Asthma : 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.
Based on 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.
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.
Typical symptoms of asthma
The symptoms of asthma vary from person to person and in any individual from time to time. It is important to remember that many of these symptoms can
be subtle and similar to those seen in other conditions. All of the symptoms mentioned below can be present in other respiratory, and sometimes, in heart conditions. This potential confusion makes
identifying the settings in which the symptoms occur and diagnostic testing very important in recognizing this disorder.
The 4 Major Recognized Symptoms: - Shortness of breath - especially with exertion or at night.
- Wheezing - a whistling or hissing sound when breathing out.
- Coughing - may be chronic; usually worse at night and early morning. May occur after exercise or when exposed to cold, dry air.
- Chest tightness - may occur with or without
the above symptoms.
Asthma Fact
Asthma is classified according to the frequency and severity of symptoms, or "attacks," and the results of pulmonary (lung)
function tests. - 30% of affected patients have mild, intermittent (less than 2 episodes a week) symptoms of asthma with normal breathing tests.
- 30% have mild, persistent (2 or mores
episodes a week) symptoms of asthma with normal breathing tests.
- 40% have moderate or severe, persistent (daily or continuous) symptoms of asthma with abnormal breathing
tests.
Acute asthma attack
An acute, or sudden, asthma attack is usually caused by an exposure to allergens or an upper respiratory tract infection. The severity of the attack depends
on how well your underlying asthma is being controlled (reflecting how well the airway inflammation is being controlled). An acute attack is potentially life-threatening because it may continue despite
the use of your usual quick-relief medications (inhaled bronchodilators). Asthma that is unresponsive to treatment with an inhaler should prompt you to seek medical attention at the closest hospital
emergency room or your asthma specialist office, depending on the circumstances and time of day. Asthma attacks do not stop on their own without treatment. If you ignore the early warning signs, you
put yourself at risk of developing "status asthmaticus." Allergy Fact
Prolonged attacks of asthma that do not respond to treatment with bronchodilators are a medical
emergency. Physicians call these severe attacks "status asthmaticus" and they require immediate emergency care.
The symptoms of severe asthma are persistent coughing and the inability to speak full sentences or walk without shortness of breath. Your chest may feel closed and your lips may have a bluish tint.
In addition, you may feel agitation, confusion, or an inability to concentrate. You may hunch your shoulders, sit or stand up to breathe more easily, and strain your abdominal and neck muscles. These
are signs of an impending respiratory system failure. At this point, it is unlikely that inhaled medications will reverse this process. A mechanical ventilator may be needed to assist the lungs and
respiratory muscles. A face mask or a breathing tube is inserted in the nose or mouth for this treatment. These breathing aids are temporary and are removed once the attack has subsided and the lungs
have recovered sufficiently to resume the work of breathing on their own. A short hospital stay in an intensive care unit may be a result of a severe attack that has not been promptly treated. To avoid
such hospitalization, it is best, at the onset of symptoms, to begin immediate early treatment at home or in your doctor's office. Allergy Fact
The presence of
wheezing or coughing in and of itself is not a reliable standard for judging the severity of an asthma attack. Very severe attacks may clog the tubes to such a degree that the lack of air in and out of
your lungs fails to even produce wheezing or coughing.
How is asthma treated?
Most asthma medications work by relaxing bronchospasm (bronchodilators) or reducing inflammation (corticosteroids). In the treatment of asthma, inhaled
medications are generally preferred over tablet or liquid medicines which are swallowed (oral medications). Inhaled medications act directly on the airway surface and airway muscles where the asthma
problems initiate. Absorption of inhaled medications into the rest of the body is minimal. Therefore, adverse side effects are fewer as compared to oral medications. Inhaled medications include beta-2
agonists, anticholinergics, corticosteroids, and cromolyn sodium. Oral medications include aminophylline, and corticosteroid tablets.
Historically, one of the first medications used for asthma was adrenaline ( heart rate , headache, nausea, vomiting, restlessness, and a sense of panic.
Medications chemically similar to adrenaline have been developed. These medications, called beta-2 agonists, have the bronchodilating benefits of adrenaline without many of its unwanted
side-effects. Beta-2 agonists are inhaled bronchodilators which are called "agonists" because they promote the action of the beta-2 receptor of bronchial wall muscle. This receptor acts to relax the
muscular wall of the airways (bronchi), resulting in bronchodilation. The bronchodilator action of beta- 2 agonists starts within minutes after inhalation and lasts for about 4 hours. Examples of these
medications include terbutaline sulfate (Brethaire).
A new group of long-acting beta-2 agonists has been developed with a sustained duration of effect of twelve hours. These inhalers can be taken twice a day. potassium .
Just as beta-2 agonists can dilate the airways, beta blocker medications impair the relaxation of bronchial muscle by beta-2 receptors and can cause constriction of airways, aggravating asthma.
Therefore, atenolol (Tenormin), should be avoided by asthma patients.
The emphysema .
When symptoms of asthma are difficult to control with beta-2 agonists, inhaled corticosteroids ( airway obstruction over time. Examples of inhaled corticosteroids include beclomethasone
dipropionate (Beclovent, Beconase, Vancenase, and Vanceril), triamcinolone acetonide (Azmacort), and flunisolide (Aerobid). The ideal dose of corticosteroids is still unknown. The side-effects of
inhaled corticosteroids include hoarseness, loss of voice, and oral yeast infections. Early use of inhaled corticosteroids may prevent irreversible damage to the airways.
histamine , which can cause asthma. Exactly how cromolyn works to prevent asthma needs further research. Cromolyn is not a corticosteroid and is usually not associated with significant side
effects. Cromolyn is useful in preventing asthma but has limited effectiveness once acute asthma starts. Cromolyn can help prevent asthma triggered by exercise, cold air, and allergic substances, such
as cat dander. Cromolyn may be used in children as well as adults.
allopurinol (Xyloprim) can further affect drug blood levels.
Corticosteroids are given orally for severe asthma unresponsive to other medications. Unfortunately, high doses of corticosteroids over long periods can have serious side effects, including high
blood pressure , thinning of the skin and easy bruising, insomnia, emotional changes, and weight gain.
Expectorants help thin airway mucus, making it easier to clear the mucus by coughing. Potassium iodide is commonly used but has the potential side-effects of Guaifenesin (Entex, Humibid) can
increase the production of fluid in the lungs and help thin the mucus, but can also be an airway irritant for some people.
In addition to bronchodilator medications for those patients with atopic asthma, avoiding allergens or other irritants can be very important. In patients who cannot avoid the allergens, or in those
whose symptoms cannot be controlled by medications, allergy shots are considered. The benefits of allergy shots (desensitization) in the prevention of asthma has not been firmly established. Some
doctors are still concerned about the risk of ragweed , and animal dander.
In some asthma patients, avoidance of aspirin, or other Asthma At A Glance - Asthma is a chronic inflammation of the bronchial tubes (airways) that causes swelling and narrowing
(constriction) of the airways. The bronchial narrowing is usually either totally or at least partially reversible with treatments.
- Asthma is now the most common chronic illness in
children, affecting 1 in every 15.
- 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.
- Allergy can play a role in some, but not all, asthma patients.
- Many factors can precipitate asthma attacks and
are they are classified as either allergens or irritants.
- Symptoms of asthma include shortness of breath, wheezing, cough, and chest tightness.
- Asthma is diagnosed based on
the presence of wheezing and confirmed with breathing tests.
- Chest x-rays are usually normal in asthma patients.
- Avoiding precipitating factors is important in the management
of asthma.
- Medications can be used to reverse or prevent bronchospasm in patients with asthma.
Based on University of Miami School of Medicine [Medical_Dictionary]:
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