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Asthma / Asthma - The Condition
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submitted by Dr. Gary Farr - Contact the author here.
Last Updated February, 13, 2002
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The symptoms of asthma vary among people and can
include wheezing, shortness of breath and tightness of the chest. Other
asthma symptoms can include: trouble controlling a cough; a persistent cough
at night; difficulty breathing during, or soon after, physical exertion or
exercise; or waking up at night because of one or more of these symptoms.
Episodes of asthma symptoms (also called asthma attacks, flare-ups or
exacerbations) occur when airways narrow, making it difficult - sometimes
impossible - to breathe.
Warning signs of an impending asthma attack may include chest tightness,
light wheezing, coughing, restlessness when trying to sleep, irritability,
itchy throat and watery eyes.
Diagnosis of allergies begins with a history and
physical exam. The person may report symptoms after a specific exposure,
such as being around cats.
Sometimes, the individual will have symptoms during particular seasons. For
those with ongoing symptoms such as nasal stuffiness, other tests can be
performed. The healthcare provider may order a test that looks for
eosinophils in the nasal mucus. Allergy testing may be done to determine the
particular triggers that cause the individual's symptoms.
 If
you know what triggers allergic asthma, the obvious strategy is to reduce
exposure to those allergens. To pinpoint what causes hyper-reactivity in the
lung in allergic asthma, allergists use skin tests, then suggest that the
patient reduce or eliminate contact with the allergens. Vacuum the floor.
Rip up the carpet. Jettison dusty crud. Nuke the roaches.
This is almost starting to sound like fun, until you remember that pet cats
are a potent cause of allergies. Bummer. Ciao, Gato.
Double bummer: The sad part is that these measures doesn't always control
allergic asthma. Some dust mites will plague the cleanest houses, and roach
control can be problematic -- to say the least -- in poor neighborhoods.
And even good allergen control still leaves patients with symptoms. That
disturbing news came from a recent test of immune therapy for allergic
asthmatics. In fact, the study contained a double whammy. The goal was to to
control allergic asthma with the same kind of allergy shots that relieve
sneezing and itching allergies. (Allergies are essentially an overreaction
of the immune system to foreign proteins, and these tiny doses of allergens
were supposed to "teach" the immune system to tolerate the allergen.)
Although such "immunotherapy" has been used for years in asthmatics, the
recent study of 121 children with severe asthma found that it just did not
work: Allergy shots reduced neither the number of emergency-room visits nor
the need for medication.
 The
results were a bit of a shock, says lead researcher N. Franklin Adkinson,
professor of medicine at the Johns Hopkins Medical Institutions.
"We were surprised at the unequivocal, across-the-board finding, that we
could not find any aspect of asthma care that was influenced." Adkinson's
allergist colleagues quickly responded that the study did not reflect the
real world. For one thing, patients actually evicted their pets, which many
patients refuse to do.
For another, the patients saw their doctors every two or three weeks, while
most patients are lucky to see their asthma doctors twice a year. Finally,
the "astounding 90 percent compliance rate" among patients did not reflect
clinical reality. That's according to Michael Kaliner, who spoke to The
Lancet (2/8/97) on behalf of the American Academy of Allergy, Asthma and
Immunology.
Adkinson admits that the subject population was inevitably tilted toward
patients who would obey the rules for the required two to three years. And
he adds that while immunotherapy did not help the severe cases who he'd
hoped would benefit, there were indications that it might help milder cases,
and/or patients with more recent diagnoses.
Norman Edelman, a consultant to the American Lung Association, says the
study should be seen in context. "If allergy shots were dramatically
successful, we'd know it by now. And if they didn't work at all, we'd know
that by now too. So it may work in some selected cases."
As we mentioned previously, there's another lesson in the results: a missing
piece of the asthma picture. These patients cleaned out their environments,
they saw their doctors, they took their meds, and they still had symptoms.
Why? Probably, Adkinson says, "due to an unknown or complicating factor."
There are any number of candidates for unknown asthma factors, but the one
that intrigued The Why Files is the personal history of infection. In a
recent Japanese study of 867 children, asthma symptoms correlated with
reactions to tuberculosis skin tests.
A positive skin test signals "exposure" to TB, meaning the person has either
had the disease or been vaccinated against it. The study found that asthma
symptoms were one-half to one-third as common among those who were exposed
to TB as those who had not been exposed. That indicates, but does not prove,
that having TB, or getting the vaccination, somehow protects against
allergic asthma.
Twenty-five years ago, asthma was treated as an
acute disease, with drugs designed to dilate, or enlarge, the bronchial
tubes that carry air inside the lung. But the biggest advance in recent
years stems from the recognition that inflammation -- the process that
prepares tissue to combat foreign bodies -- plays a crucial role in the
disease, because it sets up the lungs for acute attacks.
With the knowledge that asthma is a chronic, inflammatory disease, doctors
have begun to rely on drugs that calm the inflammation and reduce the excess
reactivity of the airways.
 The
most common of these drugs are inhaled versions of corticosteroids --
synthetic hormones that are unrelated to the anabolic steroids used by body
builders. The inhaled drugs ensure that more of the active ingredient
reaches the lungs -- although as much as 80 percent of the dose does get
ingested through the stomach.
How effective are inhaled corticosteroids? In the March 19, 1997 issue of
JAMA (the Journal of the American Medical Association), James Donohue of
Brigham and Women's Hospital in Boston reported that patients with moderate
to severe asthma who took them had half as many hospitalizations for asthma
as other patients. But does lack of hospitalizations mean asthma is
effectively treated? I think not.
New federal guidelines on asthma treatment emphasize using steroid drugs to
calm inflammation and halt the asthma process at the beginning.
In 1997, U.S. asthma doctors gained access to a new category of drugs that
affect an inflammatory mechanism involving molecules called leukotrienes.
Two so-called leukotriene inhibitors have recently been approved, and
several more are close to approval.
At first, the new drugs will be used when existing anti-inflammatories don't
work, says Marcus Cohen, an allergist in Madison, Wis. "We have to see where
they fit in; we don't know yet what population they'll best affect." In the
future, he says, other inflammatory mechanisms that have already been
identified will also become targets for drug therapy.
Furthermore, a series of experimental drugs are about to enter clinical
trials. These drugs also exploit a new understanding of how the inflammation
actually begins. Two drug companies are looking at antibodies -- think of
them as neutralizing agents -- to interleukin-5, a messenger molecule in the
inflammatory process. Tests with animals have shown that the antibodies
prevent interleukin-5 from activating eosinophils -- immune cells that play
a major role in inflammation. Clinical trials are imminent.
But better drugs and better patient advice are not
enough -- patients obviously need access to them. Part of the problem is
cost. Inner-city asthmatics who have poor access to health care tend to rely
on emergency rooms where the necessary follow-up is problematic at best. In
other cases, patients don't want to fix what doesn't seem broke: They don't
see a reason to take preventative medicine on days when they have no
symptoms, not understanding that inhaled steroids are a long-term treatment
for the inflammation that causes most asthma.
Norman Edelman, of the American Lung Association, sees the issue of patient
education as "both a problem and an opportunity. Asthma is an illness where
the active cooperation by the patient is critically important -- it leads to
better control. You send the patient home with instructions on what to watch
for, how to change medicines, about the triggers, how to deal with school,
work and home environments. It's a complicated illness, and it requires a
lot of patient know-how and activism."
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