1.4 What are the most common triggers of asthma?
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- 1.4.1 What is intrinsic/extrinsic asthma?
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- 1.4.2 Can gastric reflux trigger asthma?
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- 1.4.3 What is Occuptional asthma?
The most common triggers of asthma are:
- viral respiratory infections, such as influenza (the flu)
or bronchitis;
- bacterial infections, including sinus infections;
- allergic rhinitis;
- irritants, such as pollution, cigarette smoke, perfumes,
dust, or chemicals;
- sudden changes in either temperature or humidity, especially
exposure to cold air;
- allergens, for people with allergies;
- emotional upsets, such as stress; and
- exercise.
Intrinsic and extrinsic asthma are outdated terms which have now
been replaced by terms related to the asthma trigger, since the
inflammatory response of the airways is the same independent of
the cause of the asthma. What was known as extrinsic asthma is
now called allergic asthma, while asthma triggered by non-allergic
factors, formerly called intrinsic asthma, is separated into such
categories as exercise-induced asthma and occupational (chemical-
induced) asthma.
Yes, gastric reflux can act as an irritant which triggers
asthma. Reflux, properly known as gastroesophageal reflux,
occurs when the liquids in the stomach pass up the esophagus,
or feeding tube. Because these liquids are usually highly
acidic, they can irritate and inflame the esophagus, and
also the airways of the lung, should any of this liquid be
aspirated. This irritation can trigger an asthma attack.
Asthma flares caused by reflux are more common at night,
for it is easier for material to pass up the esophagus when
one is lying down. Some simple treatments to prevent reflux
include raising the head of the bed, not eating close to
bedtime, or using either antacids or medications such as
ranitidine (Zantac) which reduce the amount of acid produced
by the stomach.
Occupational Asthma is asthma that is caused by sensitization
from exposures in the workplace. Asthmatics whose asthma is
exacerbated by exposures in the workplace would not be classified
as having occupational asthma.
There are over 200 substances that have been documented as
causing occupational asthma, but there are probably more that
have not been recognized. The substances that are known to
cause occupational asthma can be divided into two main categories.
- High molecular weight proteins of animal or plant origins are
common causes. Things like animal dander, flour proteins, and
animal scales are frequently causes of occupational asthma.
These same things are also common causes of non-occupational
asthma. These are usually IgE-mediated responses.
- Low molecular weight chemicals that have the ability to bind
with proteins or act as haptans are causes of occupational asthma.
There may be other mechanisms involved besides the classic
IgE-mediated responses as not all those that are sensitized
have specific antibody production. Reactions may have reflex,
inflammatory, pharmacological, or immunologic pathways or a
combination of several.
Often occupational asthma is difficult to diagnosis. There are
may be immediate, late, or biphasic reactions. In late reactions
the symptoms may not occur until away from the work place.
Frequently the asthma worsens as the workweek progresses and
improves over the weekend.
Treatment for occupational asthma is basically the same as any
other asthma with a few very important exceptions. For those
that have chemically induced asthma from sensitization to that
chemical; avoidance of the trigger is essential. While steroids
and other medications are helpful in treating the symptoms, they
do not prevent the underlying sensitivity from increasing.
Once sensitized to a substance, some react to minute amounts.
Levels below current TLV levels still trigger reactions. For
a sensitized individual any exposure can cause symptoms.
Continued exposure to the triggering chemical can cause permanent
lung damage, chronic asthmatic conditions, and even death.
Medication should never be used to allow the worker to continue
to work in an environment where there is exposure to the
triggering substance. Early recognition and removal from
exposure is essential in preventing long term disability from
asthma.
Chemically induced asthma can occur both in the workplace and
outside of the workplace. There are many exposures outside of
the workplace that there are exposures to chemicals that can
induce asthma. Most physicians are not familiar with this type
of asthma. For anyone that has chemically induced asthma,
avoidance of the trigger is essential.
Contributed by:
Betty Bridges / bcb56@ix.netcom.com
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