Health Focus Archive
Today asthma is viewed as a chronic inflammatory disease of the
airways. In those susceptible to asthma, this inflammation
causes the airways to narrow periodically. This, in turn,
produces wheezing and breathlessness, sometimes to the point
where the patient gasps for air. Obstruction to air flow either
stops spontaneously or responds to a wide range of treatments,
but continuing inflammation makes the airways hyper-responsive
to stimuli such as cold air, exercise, dust mites, pollutants
in the air, and even stress and anxiety.
The number of people with asthma seems to be
increasing worldwide. Between 1982-92, the rate actually rose
by 42% in the United States. Not only is asthma becoming more
frequent, but it also is a more severe disease than before,
despite modern drug treatments. In the same 10-year period,
the death rate from asthma in the United States increased
The changes that take place in the lungs of
asthmatic persons makes the airways (the "breathing tubes,"
or bronchi and the smaller bronchioles ) hyper-reactive to
many different types of stimuli that don't affect healthy
lungs. In an asthma attack, the muscle tissue in the walls
of bronchi go into spasm, and the cells lining the airways
swell and secrete mucus into the air spaces. Both these actions
cause the bronchi to become narrowed. As a result, an asthmatic
person has to make a much greater effort to breathe in air
and to expel it.
Cells in the bronchial walls release certain
substances that cause the bronchial muscle to contract and
stimulate mucus formation. These substances, which include
histamine and a group of chemicals called leukotrienes, also
bring white blood cells into the area, which is a key part
of the inflammatory response. Many patients with asthma are
prone to react to such "foreign" substances as pollen, house
dust mites, or animal dander; these are called allergens.
On the other hand, asthma affects many patients who are not
"allergic" in this way.
Asthma usually begins in childhood or adolescence,
but it also may first appear during adult years. While the
symptoms may be similar, certain important aspects of asthma
are different in children and adults.
When asthma does begin in childhood, it often
does so in a child who is likely, for genetic reasons, to
become sensitized to common "allergens" in the environment.
When these children are exposed to house-dust mites, animal
proteins, fungi, or other potential allergens, they produce
a type of antibody that is intended to engulf and destroy
the foreign materials. This has the effect of making the airway
cells sensitive to particular materials. Further exposure
can lead rapidly to an asthmatic response. This condition
of atopy is present in at least one-third and as many as half
of the general population. When an infant or young child wheezes
during viral infections, the presence of allergy (in the child
itself or a close relative) is a clue that asthma may well
continue throughout childhood.
Allergenic materials may also play a role when
adults become asthmatic. Asthma can actually start at any
age and in a wide variety of situations. Many adults who are
not allergic do have such conditions as sinusitis or nasal
polyps, or they may be sensitive to aspirin and related drugs.
Another major source of adult asthma is exposure at work to
animal products, certain forms of plastic, wood dust, or metals.
Causes & Symptoms
In most cases, asthma is caused by inhaling
an allergen that sets off the chain of biochemical and tissue
changes leading to airway inflammation, bronchoconstriction,
and wheezing. Because avoiding (or at least minimizing) exposure
is the most effective way of treating asthma, it is vital
to identify which allergen or irritant is causing symptoms
in a particular patient. Once asthma is present, symptoms
can be set off or made worse if the patient also has rhinitis
(inflammation of the lining of the nose) or sinusitis. When,
for some reason, stomach acid passes back up the esophagus
(acid reflux), this can also make asthma worse. A viral infection
of the respiratory tract can also inflame an asthmatic reaction.
Aspirin and a type of drug called beta-blockers, often used
to treat high blood pressure, can also worsen the symptoms
The most important inhaled allergens giving rise to attacks
of asthma are: • Animal dander
• Mites in house dust
• Fungi (moulds) that grow indoors
• Cockroach allergens
• Occupational exposure to chemicals, fumes, or particles of
industrial materials in the air.
Inhaling tobacco smoke, either by smoking or
being near people who are smoking, can irritate the airways
and trigger an asthmatic attack. Air pollutants can have a
similar effect. In addition, there are three important factors
that regularly produce attacks in certain asthmatic patients,
and they may sometimes be the sole cause of symptoms. They
• Inhaling cold air (cold-induced asthma)
• Exercise-induced asthma (in certain children, asthma is caused
simply by exercising)
• Stress or a high level of anxiety.
Wheezing is often very obvious, but mild asthmatic
attacks may be confirmed when the physician listens to the
patient's chest with a stethoscope. Besides wheezing and being
short of breath, the patient may cough and may report a feeling
of "tightness" in the chest. Children may have itching on
their back or neck at the start of an attack. Wheezing is
often loudest when the patient breathes out, in an attempt
to expel used air through the narrowed airways. Some asthmatics
are free of symptoms most of the time but may occasionally
be short of breath for a brief time. Others spend much of
their days (and nights) coughing and wheezing, until properly
treated. Crying or even laughing may bring on an attack. Severe
episodes are often seen when the patient gets a viral respiratory
tract infection or is exposed to a heavy load of an allergen
or irritant. Asthmatic attacks may last only a few minutes
or can go on for hours or even days (a condition called status
Being short of breath may cause a patient to
become very anxious, sit upright, lean forward, and use the
muscles of the neck and chest wall to help breathe. The patient
may be able to say only a few words at a time before stopping
to take a breath. Confusion and a bluish tint to the skin
are clues that the oxygen supply is much too low, and that
emergency treatment is needed. In a severe attack that lasts
for some time, some of the air sacs in the lung may rupture
so that air collects within the chest. This makes it even
harder to breathe in enough air. Almost always, even patients
with the most severe attacks will recover completely.
Apart from listening to the patient's chest,
the examiner should look for maximum chest expansion while
taking in air. Hunched shoulders and contracting neck muscles
are other signs of narrowed airways. Nasal polyps or increased
amounts of nasal secretions are often noted in asthmatic patients.
Skin changes, like atopic dermatitis or eczema, are a tipoff
that the patient has allergic problems.
Inquiring about a family history of asthma
or allergies can be a valuable indicator of asthma. The diagnosis
may be strongly suggested when typical symptoms and signs
are present. A test called spirometry measures how rapidly
air is exhaled and how much is retained in the lungs. Repeating
the test after the patient inhales a drug that widens the
air passages (a bronchodilator) will show whether the airway
narrowing is reversible, which is a very typical finding in
asthma. Often patients use a related instrument, called a
peak flow meter, to keep track of asthma severity when at
Often, it is difficult to determine what is
triggering asthma attacks. Allergy skin testing may be used,
although an allergic skin response does not always mean that
the allergen being tested is causing the asthma. Also, the
body's immune system produces antibody to fight off the allergen,
and the amount of antibody can be measured by a blood test.
This will show how sensitive the patient is to a particular
allergen. If the diagnosis is still in doubt, the patient
can inhale a suspect allergen while using a spirometer to
detect airway narrowing. Spirometry can also be repeated after
a bout of exercise if exercise-induced asthma is a possibility.
A chest x-ray will help rule out other disorders.
Patients should be periodically examined and
have their lung function measured by spirometry to make sure
that treatment goals are being met. These goals are to prevent
troublesome symptoms, to maintain lung function as close to
normal as possible, and to allow patients to pursue their
normal activities including those requiring exertion. The
best drug therapy is that which controls asthmatic symptoms
while causing few or no side-effects.
Managing Asthmatic Attacks
A severe asthma attack should be treated as
quickly as possible. It is most important for a patient suffering
an acute attack to be given extra oxygen. Rarely, it may be
necessary to use a mechanical ventilator to help the patient
breathe. A beta-receptor agonist is inhaled repeatedly or
continuously. If the patient does not respond promptly and
completely, a steroid is given. A course of steroid therapy,
given after the attack is over, will make a recurrence less
Long-term asthma treatment is based on inhaling
a beta-receptor agonist using a special inhaler that meters
the dose. Patients must be instructed in proper use of an
inhaler to be sure that it will deliver the right amount of
drug. Once asthma has been controlled for several weeks or
months, it is worth trying to cut down on drug treatment,
but this must be done gradually. The last drug added should
be the first to be reduced. Patients should be seen every
one to six months, depending on the frequency of attacks.
Starting treatment at home, rather than in
hospital, makes for minimal delay and helps the patient to
gain a sense of control over the disease. All patients should
be taught how to monitor their symptoms so that they will
know when an attack is starting, and those with moderate or
severe asthma should know how to use a flow meter. They should
also have a written "action plan" to follow if symptoms suddenly
become worse, including how to adjust their medication and
when to seek medical help. If more intense treatment is necessary,
it should be continued for several days. Over-the-counter
"remedies" should be avoided. When deciding whether a patient
should be hospitalized, the past history of acute attacks,
severity of symptoms, current medication, and whether good
support is available at home all must be taken into account.
Most patients with asthma respond well when
the best drug or combination of drugs is found, and they are
able to lead relatively normal lives. More than half of affected
children stop having attacks by the time they reach 21 years
of age. Many others have less frequent and less severe attacks
as they grow older. Urgent measures to control asthma attacks
and ongoing treatment to prevent attacks are equally important.
A small minority of patients will have progressively more
trouble breathing and they run a risk of going into respiratory
failure and they must receive intensive treatment.