-
- 1.0.1 What is chronic asthmatic bronchitis?
-
- 1.0.2 What is status asthmaticus?
-
- 1.0.3 What is anaphylactic shock?
-
- 1.0.4 What is COPD?
-
- 1.0.5 What is emphysema?
-
- 1.0.6 What is bronchitis?
-
- 1.0.7 What is pneumonia?
-
- 1.0.8 What is cystic fibrosis?
Asthma is best described by its technical name: Reversible
Obstructive Airway Disease (ROAD). In other words, asthma
is a condition in which the airways of the lungs become
either narrowed or completely blocked, impeding normal
breathing. However, in asthma, this obstruction of the lungs
is reversible, either spontaneously or with medication.
Quickly reviewing the structure of the lung: air reaches the
lung by passing through the windpipe (trachea), which divides
into two large tubes (bronchi), one for each lung. Each
bronchi further divides into many little tubes (bronchioles),
which eventually lead to tiny air sacs (alveoli), in which
oxygen from the air is transferred to the bloodstream, and
carbon dioxide from the bloodstream is transferred to the air.
Asthma involves only the airways (bronchi and bronchioles),
and not the air sacs. The airways are cleaned by trapping
stray particles in a thin layer of mucus which covers the surface
of the airways. This mucus is produced by glands inside the
lung, and is constantly being renewed. The mucus is then
either coughed up or swept up to the windpipe (trachea) by
cilia, tiny hairs on the lining of the airways. Once the
mucus reaches the throat, it can again be coughed up or,
alternatively, swallowed.
Although everyone's airways have the potential for constricting
in response to allergens or irritants, the asthmatic's airways
are oversensitive, or hyperreactive. In response to stimuli,
the airways may become obstructed by one of the following:
- constriction of the muscles surrounding the airway;
- inflammation and swelling of the airway; or
- increased mucus production which clogs the airway.
Once the airways have become obstructed, it takes more effort
to force air through them, so that breathing becomes laboured.
This forcing of air through constricted airways can make a
whistling or rattling sound, called wheezing. Irritation of
the airways by excessive mucus may also provoke coughing.
Because exhaling through the obstructed airways is difficult,
too much stale air remains in the lungs after each breath.
This decreases the amount of fresh air which can be taken in
with each new breath, so not only is there less oxygen
available for the whole body, but more importantly, the high
concentration of carbon dioxide in the lungs causes the blood
supply to become acidic. This acidity in the blood may rise
to toxic levels if the asthma remains untreated.
f
Chronic asthmatic bronchitis is the condition in which the
airways in the lungs are obstructed due to both persistent
asthma and chronic bronchitis (see sections 1.0 and 1.0.6).
People with this disease generally also have a persistent
cough which brings up mucus. Chronic asthmatic bronchitis
which also involves emphysema is usually classified under
the more general category of COPD.
Status asthmaticus is defined as a severe asthma attack that
fails to respond to routine treatment, such as inhaled
bronchodilators, injected epinephrine (adrenalin), or
intravenous theophylline.
Anaphylactic shock is defined as a severe and potentially
life-threatening allergic reaction throughout the entire
body. It occurs when an allergen, instead of provoking a
localized reaction, enters the bloodstream and circulates
through the entire body, causing a systemic reaction.
(There may also be an intrinsic trigger, as some cases of
exercise-induced anaphylaxis have been reported.)
The symptoms of anaphylactic shock begin with a rapid
heartrate, flushing, swelling of the throat, nausea, coughing,
and chest tightness. Severe wheezing (asthma), cramping, and
a rapid drop in blood pressure follow, which may lead to cardiac
arrest. Hives and vomiting are also common features. The
treatment for anaphylaxis is intravenous epinephrine (adrenalin),
with antihistamines and steroids also being used in selected
cases. Aminophylline may also be given for pronounced asthmatic
reactions that do not respond to epinephrine.
COPD is chronic obstructive pulmonary disease, also known as
either COAD, for chronic obstructive airway disease, or COLD,
for chronic obstructive lung disease. COPD is a disease in
which the airways are obstructed due to a combination of
asthma, emphysema, and chronic bronchitis. The 1987 Merck
Manual notes that "the term COPD was introduced because these
conditions often coexist, and it may be difficult in an
individual case to decide which is the major one producing
the obstruction."
[Maintainer's note: the entries for COPD, emphysema, bronchitis,
pneumonia, and cystic fibrosis have been included because of
common confusion between the various diseases which can affect
the lungs.]
Emphysema is the disease in which the air sacs themselves, rather
than the airways, are either damaged or destroyed. This is an
irreversible condition, leading to poor exchange of oxygen and
carbon dioxide between the air in the lungs and the bloodstream.
Bronchitis is an inflammation of the bronchi, the large airways
inside the lungs. (Bronchiolitis is the inflammation of the
bronchioles, the small airways.) This inflammation often leads
to increased mucus production in the airways.
Bronchitis is generally caused either by a virus or by exposure
to irritants such as dust, fumes, or cigarette smoke. If caused
by a virus, the bronchitis will likely be only temporary. In
the case of prolonged exposure to irritants, particularly
cigarette smoking, if there is permanent damage to the bronchi,
bronchitis may become chronic.
Pneumonia is an infection of the lung tissue. In adults, it is
generally caused by bacterial infections, though viruses, fungi,
and protozoa may also be culprits. The latter microorganisms
have become very common as causes of pneumonia in immunosuppressed
persons, such as those with HIV infection. However, for those
with chronic illnesses, especially cardiac or respiratory
diseases, or those at increased risk for pneumonia, there is a
pneumococcal pneumonia vaccination available as a preventive
measure for the most common of these bacterial infections,
streptococcus pneumoniae. In children, pneumonia is most
commonly caused by viruses.
Cystic fibrosis is a disease in which excessive amounts of
unusually thick mucus are produced throughout the body.
Because this mucus production also occurs in the lungs,
people with cystic fibrosis are extraordinarily prone to
bacterial infections which result in progressive lung damage.
Cystic fibrosis can be diagnosed by a "sweat test" as people
with cystic fibrosis have elevated chloride levels in their
perspiration. This condition often resembles asthma in
children.
Alt.Support.Asthma FAQ - Home