ASTHMA

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ASTHMA

• A GROWING PROBLEM

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What is Asthma?

• Asthma is a chronic, inflammatory lung disease in
  which the airways become blocked or narrowed.
  These effects are usually temporary, but they
  cause shortness of breath, breathing trouble, and
  other symptoms. If an asthma episode is severe, a
  person may need emergency treatment to restore
  normal breathing.
• Asthma is characterized by acute episodes in
  which breathing becomes more difficult. Typical
  symptoms of asthma include wheezing, shortness of
  breath, chest tightness, and coughing. People
  with asthma typically have extra sensitive or
  hyperresponsive airways in their lungs. An acute
  asthma episode results when trigger substances
  irritate tissues in the airways, causing them to
  become red, swollen, and narrow. The resulting
  bronchoconstriction (muscles that encircle the
  airways tighten or go into spasm) makes it
  difficult for the asthma sufferer to take air in
  and out of the lungs.

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Asthma
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Lung
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Prevalence of Asthma

• It is this country's most common and costly
  illness.
• The prevalence of asthma has been increasing
  since the early 1980s across all age, sex and
  racial groups. However, the prevalence of asthma
  is higher among children than adults, and higher
  among blacks than whites.
• An estimated 17 million Americans suffer from
  asthma, nearly 5 million are under age 18. It is
  the most common chronic childhood disease,
  affecting more than one child in 20.

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Deaths

• Asthma is the only chronic disease, besides AIDS
  and TB, with an increasing death rate. Each day
  14 Americans die from asthma.
• From 1979 to 1992, asthma death rates increased
  58 percent overall. The death rate for children
  19 years and younger increased by 78 percent
  between 1980 and 1993.
• More females die of asthma than males and more
  blacks die of asthma than whites.
• Certain factors indicate that many asthma-related
  deaths and hospitalizations are preventable when
  asthma is properly managed.

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The Costs

• The cost of asthma in 1998 was estimated to be
  11.3 billion. Direct costs accounted for 7.5
  billion and indirect costs were 3.8 billion.
  Hospitalizations accounted for the single largest
  portion of the cost.
• Among children ages 5 to 17, asthma is the
  leading cause of school absences from a chronic
  illness. It accounts for an annual loss of more
  than 10 million school days per year and more
  hospitalizations than any other childhood
  disease. Children with asthma spend an estimated
  7.3 million days per year restricted to bed.
• For adults, asthma is the fourth leading cause of
  work loss, resulting in nine million lost
  workdays each year.
• Asthma also accounts for about 1.8 million
  emergency room visits and 10 million doctor
  office visits each year.
• Asthma results in about a half million
  hospitalizations each year.

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What Triggers Asthma?

• An asthma episode is triggered by things in the
  environment. These triggers vary from person to
  person, but common ones include cold air
  exercise allergens (things that cause allergies)
  such as dust mites, mold, pollen, animal dander
  or cockroach debris and some types of viral
  infections.
• It is in the bronchi and bronchioles that asthma
  has its main effects.
• Here is how the process occurs. When the airways
  come into contact with an asthma trigger, the
  tissue inside the bronchi and bronchioles becomes
  inflamed. At the same time, the muscles on the
  outside of the airways tighten up (constriction),
  causing them to narrow. A thick fluid (mucus)
  enters the airways, which become swollen. The
  breathing passages are narrowed still more, and
  breathing is hampered.

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Lymphocyte
Lymphocytes produce IGE and various
interleukins. IGE may be bound to mast cells or
basophils. If they are produced in the presence
of allergens, they May bind to the cells and
to the allergen. They release histamine which
causes inflammation of tissue and allergy
problems. The cells Also release
cytokines, Interleukins and prosta- glandins
which attract eosinophils and other cells.
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Eosinophil
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Who Gets Asthma?

• The process just described can be normal, up to a
  point. Everyone's airways constrict somewhat in
  response to irritating substances like dust and
  mold. But in a person with asthma, the airways
  are hyperreactive. This means that their airways
  overreact to things that would just be minor
  irritants in people without asthma.
• To describe the effects of asthma, some doctors
  use the term "twitchy airways." This is a good
  description of how the airways of people with
  asthma are different from those without the
  disease.
• People with asthma have too much leukotrienes.

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What Are Risk Factors for Asthma?

• Heredity. To some extent, asthma seems to run in
  families.
• Allergies For reasons that are not fully known,
  some people seem to inherit a tendency to develop
  allergies. This is not to say that a parent can
  pass on a specific type of allergy to a child. In
  other words, it doesn't mean that if your mother
  is allergic to bananas, you will be too. But you
  may develop allergies to something else, like
  pollen or mold.
• Substances in the environment that cause
  allergiesthings like dust, mold or pollenare
  known as allergens. In a person with allergies,
  the body responds to allergens by producing
  certain kinds of proteins called immunoglobulin E
  (IgE) antibodies. Antibodies are proteins that
  the body produces to fight off foreign invaders.
  One way to test a person for allergies is to
  perform skin tests with extracts of the allergens
  or do blood tests for IgE antibodies to these
  allergens.

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What Are Some Asthma Triggers?

• Allergens. In many people with asthma, the same
  substances that cause allergy symptoms can also
  trigger an asthma episode. These allergens may be
  things that you inhale, such as pollen or dust,
  or things that you eat, such as shellfish.
• Tobacco smoke.  Smoking and secondhand cigarette
  smoke. Studies have shown a clear link between
  secondhand smoke and asthma, especially in young
  people. Passive smoking worsens asthma in
  children and teens and may cause up to 26,000 new
  cases of asthma each year.
• Exercise. Exerciseespecially in cold air. A
  form of asthma called exercise-induced asthma is
  triggered by physical activity. The kind of
  physical activities that can bring on asthma
  symptoms include not only exercise, but also
  laughing, crying, holding one's breath, and
  hyperventilating (rapid, shallow breathing).

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Common Asthma Triggers

• Dust/Dust Mites
• Cockroaches
• Mammal fur/saliva/urine
• Mold
• Pollen
• Second hand cigarette smoke
• Chemical irritants Scented products, fabric
  finishers

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Dust Mites
Dust mites are microscopic, insect-like creatures
that live in bedding, carpets and upholstered
furniture. The waste they produce causes
allergic symptoms in 30-60 million Americans.
Pillows and mattresses are a virtual paradise
for dust mites because they thrive in warm, humid
conditions while gorging themselves on shed human
skin cells.
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Cockroaches

• Cockroaches Many people with asthma are allergic
  to the dried droppings and remains of
  cockroaches.

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Pollen from Plants
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How Is Asthma Treated?

• Because each case of asthma is different,
  treatment needs to be tailored for each person.
  One general rule that does apply, though, is
  removing the things in your environment that you
  know are factors that make your asthma worse.
  When these measures are not enough, it may be
  time to try one of the many medications that are
  available to control symptoms.
• Asthma medications may be either inhaled or in
  pill form and are divided into two
  typesquick-relief and long-term control.
  Quick-relief medicines are used to control the
  immediate symptoms of an asthma episode. In
  contrast, long-term control medicines do not
  provide relief right away, but rather help to
  lessen the frequency and severity of episodes
  over time.

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Causes of Asthma

• People spend more time indoors. We are therefore
  exposed to more indoor allergens, such as dust
  mite allergen, that cause asthma. Our houses are
  now hermetically sealed to save heating and
  cooling energy and unfortunately this causes more
  indoor allergen exposure.
• People today live in cleaner, more sanitary
  conditions than they did before the industrial
  revolution, relatively free of disease-causing
  viruses and bacteria. This clean living affects
  our immune system. The immune system's defensive
  white blood cells, called T cells, have two basic
  "settings. Th1 cells fight infectious viruses
  and bacteria. Th2 cells fight parasites but are
  also involved in allergic reactions.
• We are exposed to fewer viruses and bacteria than
  people were 100 years ago, so perhaps our immune
  systems have not learned to make Th1 cells as
  well. That means we have a greater proportion of
  Th2 cells in our bodies, which might lead to more
  allergies and asthma.
• Other theories point to increased levels of air
  pollutants, a decline in the amount of exercise
  people get, or rising obesity as factors in the
  increase of asthma.

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Diagnosing Asthma

• A diagnosis of asthma usually is based on the
  patient's symptoms, medical history, a physical
  examination, and laboratory tests that measure
  pulmonary (lung) function. Doctors typically look
  for signs that the patient's airflow is
  obstructed and that the obstruction is at least
  partially reversible.
• Evidence of reversible airway obstruction is
  often detected in the physical examination or by
  physiologic testing. Physiologic testing
  generally is recommended to confirm the
  diagnosis. During an asthma attack, wheezing can
  be heard by listening to the chest with a
  stethoscope. The airway obstruction is considered
  reversible if the wheezing disappears in response
  to treatment, or when the suspected triggering
  factor is removed or resolved.

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Spirometry Test

• Spirometry The most reliable way to determine
  reversible airway obstruction is with spirometry,
  a test that measures the amount of air entering
  and leaving the lungs. This simple test can be
  performed in the physician's office.
• Spirometry uses a measuring device called a
  spirometer that is connected by a flexible tube
  to a disposable cardboard mouthpiece. The patient
  exhales and inhales deeply, then seals his or her
  lips around the mouthpiece and blows as
  forcefully and for as long as possible until all
  the air is exhaled from the lungs.

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Asthma attacks are not all the samesome are
worse than others. In a severe asthma attack,
the airways can close so much that not enough
oxygen gets to vital organs. This condition is a
medical emergency. People can die from severe
asthma attacks.
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Treatment for Asthma
A leukotriene antagonist. This drug binds to
receptors and blocks the ability of leukotrienes
to bind and trigger asthma. This drug provides
long term treatment.
Albuterol rescue drugs for acute asthma
attacks. This drug provides quick relief.
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Medications

• Long-term-control medications. These are used
  regularly to control chronic symptoms and prevent
  asthma attacks.
• Quick-relief medications. You use these as needed
  for rapid, short-term relief of symptoms during
  an asthma attack.
• Allergy control. Decrease sensitivity to
  allergens.

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Long-Term Medication

• Inhaled Corticosteroids
• The most effective medications for asthma. They
  reduce inflammation in your airways and prevent
  blood vessels from leaking fluid into your airway
  tissues.
• Help decrease the frequency of attacks and reduce
  the need for other medications. Because inhaled
  corticosteroids control most forms of asthma by
  delivering medication directly to your airways,
  they have a lower risk of side effects than are
  associated with oral corticosteroids. Inhaled
  corticosteroids include Floven), Pulmicort,
  Azmacort, Aerobid, Qvar.
• Side effects associated with inhaled
  corticosteroids can include hoarseness or loss of
  voice, oral yeast infections (thrush), and cough.
  Long-term use of inhaled corticosteroids may
  slightly increase the risk of skin thinning,
  bruising, osteoporosis, eye pressure and
  cataracts. In children, inhaled corticosteroids
  may slow growth.
• Long-acting beta-2 agonists. A group of
  medications called bronchodilators, which open up
  constricted airways.
• Leukotriene modifiers. Reduce the production or
  block the action of leukotrienes substances
  released by cells in your lungs during an asthma
  attack. Leukotrienes cause the lining of your
  airways to become inflamed, which in turn leads
  to wheezing, shortness of breath and mucus
  production. Leukotriene modifiers include
  Singulair and Accolate.
• Cromolyn (Intal). Preventative inhaler.

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New from Genentech

• Anti-IgE monoclonal antibodies. If you have
  allergies, your immune system produces
  allergy-causing IgE antibodies to attack
  substances that generally cause no harm, such as
  pollen, dust mites and pet dander. If you have
  allergic asthma that's difficult to control
  (Xolair) may reduce the number of asthma attacks
  you experience by blocking the action of these
  antibodies. That way your immune system isn't
  prompted to react and cause the inflammation that
  makes breathing difficult.

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Respiratory System
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Lung Capacities

• The amount of air a person breathes in and out at
  rest is called the Tidal Volume (Vt about 500ml).
  During such breathing, a person could actually
  take in more air or blow more out. The additional
  amount a person could inhale, such as during
  maximum physical activity, is called the
  Inspiratory Reserve Volume (IRV 3,000 ml). The
  additional amount a person could exhale is called
  the Expiratory Reserve Volume (ERV 1,000 ml). The
  Residual Volume (RV) is the amount of air that
  stays in the lung even after maximum expiration.
• "Capacities" are combinations of two or more
  volumes.  
• The Total Lung Capacity (TLC) is the total amount
  of air the lungs can contain  TLC RV ERV
  Vt IRV
• The Vital Capacity (VC) is the total amount of
  air the person can breathe in and out VC ERV
  Vt IRV
• Functional Residual Capacity (FRC) is the total
  amount of air left in the lungs at the end of a
  normal exhalation FRC RV ERV