ASTHMA
A
THE CAUSE OF ASTHMA
Breathlessness and wheezing in
asthma are caused by narrowing of
the bronchioles (small airways in the
lungs). Asthma can be triggered by a
wide variety of stimuli, including
exercise, infection, pollen, and dust,
which would have no effect on non-
asthmatic people.
Inflammation ofthe linings
of these bronchioles results in
increased production of sputum
(phlegm), which makes the
obstruction worse. A dry cough
often develops as the sufferer
attempts to clear the airways.
Effect of
asthma on
the lungs
TREATMENT OF AN ASTHMA ATTACK
Attacks are treated by inhalation of a bronchodilator drug from an inhaler. For a
severe attack, a nebulizer can be used to dispense the drug as fine mist through
a face mask or mouthpiece. Babies, young children, or any adults who are
unable to coordinate their breathing, require a spacer.
Using an inhaler
To use the inhaler correctly, exhale first then
tilt the head back. Take in a slow, deep breath
while releasing the drug by depressing the
canister. Two puffs should increase air flow
within 15 minutes.
Healthy bronchiole
Obstructed bronchiole
Inhalation ofthe
Before treatment, the
r
bronchodilator widens
airflow is obstructed
the bronchiole and
bya narrowing ofthe
improves airflow.
bronchiole.
Using a spacer
The inhaler, fitted with a spacer and face
mask, is placed over the baby’s nose and
mouth. This allows the babyto inhale the
drug while breathing normally.
T r e e
__
G r a s s
^
M o u ld s
1
1
1
1
1
1
J
F
M
A
M
J
\
1
1
J
A
S
1
1
1
O
N
D
Seasonal asthma
When symptoms occur only during a few
months, the cause is likely to be allergy to
pollen or spores.
TYPES AND CAUSES
In some people, an allergic response
triggers the swelling and inflammation
in the airways. This allergic type of
asthma tends to occur in childhood,
and it may develop in association with
the allergic skin condition,
eczema
or
certain other allergic conditions such as
hay fever (see
rhinitis, allergic).
Suscep-
tibility to these conditions frequently
runs in families.
Some substances are known to trigger
attacks of allergic asthma (see
allergens).
These include pollen, house-dust mites,
mould,
feathers,
and
dander
(tiny
scales) 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 people with asthma are
sensitive to
aspirin,
and taking it may
trigger an attack.
When asthma starts in adulthood, there
are usually no identifiable allergic trig-
gers. The
first
attack
is
sometimes
brought on by a respiratory tract infec-
tion, stress, or anxiety.
In some cases, a substance that is
inhaled regularly in the work environ-
ment can result in the development
of asthma in a previously healthy per-
son. This is known as
occupational
asthma, and it is one of the few occupa-
tional
lung
diseases
that
are
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.
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 vehicles
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.
SYMPTOMS
Asthma attacks can vary in severity from
mild breathlessness to
respiratory failure.
The
main symptoms are wheezing,
breathlessness, dry cough, and a tight-
ness in the chest. In a severe attack,
breathing becomes increasingly diffi-
cult, resulting in a low level of oxygen
74
previous page 73 BMA A Z Family Medical Encyclopedia   2004 read online next page 75 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off