ASTHMA
ASTHMA
A
childhood and may develop in associa-
tion
with
eczema
or
certain
other
allergic conditions such as hay fever
(see
rhinitis, allergic).
Susceptibility to
these conditions frequently runs in fam-
ilies and may be inherited.
Some substances, called
allergens
, are
known to trigger attacks of allergic asth-
ma. They include pollen, house-dust
mites, mould, and
dander
and saliva
from furry animals such as cats and
dogs. Rarely, certain foods, such as
milk, eggs, nuts, and wheat, provoke an
allergic asthmatic reaction. Some peo-
ple with asthma are sensitive to
aspirin
,
and taking it may trigger an attack.
When asthma starts in adulthood,
there are usually no identifiable allergic
triggers. The 1st attack is sometimes
brought on by a respiratory infection.
Factors that can provoke attacks in a
person with asthma include cold air,
exercise, smoke, and occasionally emo-
tional
factors
such
as
stress
and
anxiety. Although industrial pollution
and exhaust emission from motor vehi-
cles do not normally cause asthma,
they do appear to worsen symptoms in
people who already have the disorder.
Pollution in the atmosphere may also
trigger asthma in susceptible people.
In some cases, a substance that is
inhaled regularly in the work environ-
ment can cause a previously healthy
person to develop asthma. This type is
called occupation asthma and is one of
the few occupational lung diseases that
is still increasing in incidence.
There are currently about 200 sub-
stances used in the workplace that are
known to trigger symptoms of asthma,
including glues, resins, latex, and some
chemicals, especially isocyanate chemi-
cals used in spray painting. However,
occupational asthma can be difficult to
diagnose because a person may be reg-
ularly exposed to a particular trigger
substance for weeks, months, or even
years before the symptoms of asthma
begin to appear.
Asthmatic attacks can vary in severity
from mild breathlessness to
respiratory
failure.
The main symptoms are wheez-
ing, breathlessness, dry cough, and
tightness in the chest. In a severe attack,
NORMAL AIRWAY
Narrowed
AIRWAY DURING ASTHMA ATTACK
breathing becomes increasingly difficult,
resulting in a low level of oxygen in the
blood. This causes
cyanosis
(bluish dis-
coloration) of the face, particularly the
lips. Untreated, such attacks may be fatal.
There is no cure for asthma, but at-
tacks can be prevented to a large extent
if a particular allergen can be identified.
Treatment involves inhaled
broncho-
dilator drugs
(sometimes known as
relievers) to relieve symptoms. When
symptoms
occur
frequently,
or
are
severe, inhaled
corticosteroids
are also
prescribed. These drugs are used con-
tinuously to prevent attacks by reducing
inflammation in the airways and are
also known as preventers.
Other drug treatments include
sodium
cromoglicate
and nedocromil sodium,
which are useful in preventing exercise-
induced asthma. A new group of drugs
called
leukotriene receptor antagonists
may reduce the dose of corticosteroid
needed to control the condition.
Theo-
phylline
or the inhaled anticholinergic
drug
ipratropium
may also be used as
55
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