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Many terms are used to
describe asthma and asthma management. Included in this glossary are those words
that need to be defined precisely so that their meaning may be clearly
understood and not confused with usages elsewhere.
Acute
- Brief (days to weeks).
Airflow limitation
- A prolonged forced expiratory time (ie, longer than four seconds). "Airflow
limitation" is preferred to other phrases such as "airway obstruction" and
"airway narrowing" that imply specific mechanisms of airflow limitation.
"Airflow limitation" reflects the heterogeneity of the mechanisms involved in
the physiological abnormalities of asthma.
Airway
hyperresponsiveness - Describes
airways that narrow too easily or too much in response to a provoking stimulus.
In asthma, airways can be hyperresponsive to many different stimuli.
Allergen
- A protein that causes one to have an allergic reaction. Examples include
foods, animal dander and some drugs.
Antibody
- A protein (also called an immunoglobulin) that is manufactured by lymphocytes
(a type of white blood cell) to neutralize an antigen or foreign protein.
Bacteria, viruses and other microorganisms commonly contain many antigens, as do
pollens, dust mites, molds, foods and other substances. Although many types of
antibodies are protective, inappropriate or excessive formation of antibodies
may lead to illness. When the body forms a type of antibody called IgE
(immunoglobulin E), allergic rhinitis, asthma or eczema may result when the
patient is again exposed to the substance, which caused IgE antibody formation
(allergen).
Antigen
- A substance that can trigger an immune response, resulting in production of an
antibody as part of the body's defense against infection and disease. Many
antigens are foreign proteins (those not found naturally in the body). An
allergen is a special type of antigen that causes an IgE antibody response.
Anti-inflammatory
- Inhibiting one or more of the
components of the inflammatory reaction.
Asthma
- The operational definition: Asthma is a chronic inflammatory disorder
in which many cells play a role, in particular mast cells, eosinophils and T
lymphocytes. In susceptible individuals this inflammation causes recurrent
episodes of wheezing, breathlessness, chest tightness and cough particularly at
night and/or in the early morning. These symptoms are usually associated with
widespread but variable airflow limitation that is at least partly reversible
either spontaneously or with treatment. The inflammation also causes an
associated increase in airway responsiveness to a variety of stimuli.
Epidemiological definitions:
Questionnaire definitions are often given in terms of symptoms alone. They
include "wheeze ever" (the least useful data because responses are influenced by
the ability to recall the events) and "diagnosed asthma" (more valuable because
of medical certification). "Current asthma" - defined as symptoms of asthma
within the past year associated with airway hyperresponsiveness, as indicated by
inhalation of histamine or methacholine or by exercise challenge - may be the
most useful epidemiological definition because it describes people with
clinically important asthma.
Asthma is a "disorder" rather than a
"disease." Many factors contribute to airflow limitation in asthma, each related
to the inflammatory process; these factors may vary within and between
individuals. This leads to a marked variability of clinical presentation. This
also leads to the hypothesis that asthma is not a single disease but rather is a
common clinical expression of possibly different pathogenic mechanisms.
Asthma management
- A comprehensive approach to achieving and maintaining control of asthma. It
includes patient education to develop a partnership in management, assessing and
monitoring severity, avoiding or controlling asthma triggers, establishing plans
for medication and management of exacerbations, and regular follow-up care.
Asthma specialist
- Health care professional who has
received specific training in the diagnosis and management of asthma.
Atopy
-The propensity, usually genetic, for
developing IgE-mediated responses to common environmental allergens.
Bronchoconstriction
- Airflow limitation due to
contraction of airway smooth muscle. "Bronchoconstriction" is preferred to the
word "bronchospasm."
Bronchodilator drugs
- A group of drugs that widen the
airways in the lungs.
Causal factors
- Risk factors that sensitize the airways and cause the onset of asthma
symptoms. The most important of these are allergens and chemical sensitizers.
Chronic
- Remains for several years, possibly a
lifetime.
Contributing factors
- Risk factors that either augment the likelihood of asthma developing upon
exposure to a risk factor or may even increase susceptibility to asthma. These
factors include smoking, viral infections, low birthweight and environmental
pollutants.
Controller medications
- Medications taken daily on a long-term basis that are useful in getting
persistent asthma under control and in maintaining control. They include
anti-inflammatory agents and long-acting bronchodilators. Anti-inflammatory
agents, particularly inhaled corticosteroids, are at present the most effective
controller medications. Controller medications are also sometimes called
prophylactic, preventive, regular preventive or maintenance medications.
Corticosteroid drugs
- A group of anti-inflammatory drugs
similar to the natural corticosteroid hormones produced by the adrenal glands.
Among the disorders that often improve with corticosteroid treatment are asthma,
allergic rhinitis, eczema and rheumatoid arthritis.
Cost-of-illness
evaluation - Empiric description of
the economic consequences of illness on individuals or populations.
Disorder versus disease
- Disorder implies a health condition with multiple causative mechanisms;
disease implies a single pathology and etiology.
Economic impact
- Effects of a health condition such as
asthma measured through direct medical care costs of health services for
prevention and treatment; indirect costs in terms of the value of related
morbidity, premature mortality, and productivity loss; and intangible costs
associated with the value of the psychosocial impacts of a condition.
Environmental control
- Removal of risk factors from the environment.
Exacerbate
To aggravate or make worse. "Exacerbate" is preferred to the words "cause,"
"precipitate," "induce" and "incite."
Exacerbation
- Any worsening. Onset can be acute and
sudden, or gradual over several days. A correlation between symptoms and peak
flow is not necessarily found. "Exacerbation" replaces the words "attack" and
"episode."
Extrinsic asthma
- Asthma that is triggered by an allergic reaction, usually something that is
inhaled, or in the environment.
Guided self-management
- Providing patients and their
families with suitable information and training so that the patient can keep
well and adjust treatment according to a medication plan developed with the
health care professional.
Health care
professional - Individual who is
licensed to care for sick people. Among these: physicians, nurses,
nurse-practitioners, physician assistants, therapists, etc.
Histamine
- A chemical present in cells throughout the body that is released during an
allergic or inflammatory reaction. It is responsible for narrowing the bronchi
or airways in the lungs during an asthma exacerbation.
Irritant
- Risk factor or trigger that may cause increased symptoms and/or airflow
limitation.
Immune system
- A collection of cells and proteins that protects the body from potentially
harmful, infectious microorganisms (microscopic life-forms), such as bacteria,
viruses and fungi. The immune system plays a role in the control of cancer and
other diseases but also is the culprit in the phenomena of allergies,
hypersensitivity and the rejection of transplanted organs, tissues and medical
implants.
Immunoglobulins
- Also known as antibodies. Proteins found in blood and in tissue fluids.
Immunoglobulins are produced by cells of the immune system called B-lymphocytes.
Their function is to bind to substances in the body that are recognized as
foreign antigens (often proteins on the surface of bacteria and viruses). This
binding is a crucial event in the destruction of the microorganisms that bear
the antigens. Immunoglobulins also play a central role in allergies when they
bind to antigens that are not necessarily a threat to health and provoke an
inflammatory reaction.
Inflammation
- Inflammation is the redness, swelling, heat and pain in a tissue due to
chemical or physical injury, or to infection. It is a characteristic of allergic
reactions in the nose, lungs and skin.
Intrinsic asthma
- Asthma that has no apparent external
cause.
Lymphocyte
- Any of a group of white blood cells of crucial importance to the adaptive part
of the body's immune system. The adaptive portion of the immune system mounts a
tailor-made defence when dangerous invading organisms penetrate the body's
general defenses.
Mast cell
- These cells play an important role in the body's allergic response. Mast cells
are present in most body tissues, but are particularly numerous in connective
tissue, such as the dermis (innermost layer) of skin, and also are found in the
airways. Following subsequent allergen exposure, the mast cells release
substances such as histamine (a chemical responsible for allergic symptoms) into
the tissue.
Medication plan
- A specific plan, preferably written (or
pictorial for low-literacy populations), to achieve and maintain control of
asthma based on use of controller and reliever medications in a stepwise
approach. A medication plan also includes instructions on how to recognize
worsening of asthma and what actions to take (this part of the medication plan
is often referred to as the "action plan" because it outlines how to start
treatment of an exacerbation and when and how to seek medical care).
Patient education
- The aim of patient education is
"guided self-management." The health care professional provides the patient and
the patient's family with suitable information and training so that the patient
can stay well and adjust treatment according to a medication plan developed with
the health care professional. Effective patient education involves a partnership
between patient and health care professional with frequent revision and
reinforcement. Training includes teaching specific asthma management skills such
as how to take medicine correctly, how to recognize when asthma gets worse, and
what actions to take to achieve and maintain control.
PEF (peak expiratory
flow) home monitoring - Measurement
of PEF on a regular basis at home with a portable peak flow meter. PEF home
monitoring is especially useful in patients over 5 years of age (who have the
ability to use the flow meter) with moderate persistent to severe persistent
asthma.
Prevention
- Primary prevention is preventing development of the condition of asthma.
Secondary prevention is preventing exacerbations of asthma in those who already
have the condition and avoiding deterioration in lung function or death from the
condition.
Reliever medications
- Short-acting bronchodilating medications that act quickly to relieve airflow
limitation and its accompanying acute symptoms such as cough, chest tightness
and wheezing. Relievers are also sometimes called quick relief medicine or
rescue medicine.
Risk factor
- An agent that when present increases the probability of disorder expression.
There are two types of risk factors:
- Risk
factors involved in the development of the condition of asthma. For example,
a risk factor for the onset of asthma can be inherited, such as atopy.
Alternatively, a risk factor can be due to environmental exposure. See
"causal factors" and "contributing factors."
- Risk
factors that cause asthma exacerbations in individuals who already have the
condition. These are also called triggers (for example, dust; mites;
exercise; cold, dry air).
Social impact
- Effects of a health condition on social functioning. In asthma, social impacts
include impaired child development and education as well as disruption and loss
of adult employment and productivity.
Stepwise approach
- The number (type) and frequency of medications are increased with increasing
severity of symptoms. The aim is to accomplish the goals of therapy with the
least possible medication.
Theophylline
- Theophylline is a bronchodilator drug, given by mouth, that widens the airways
to the lung.
Trigger
- A risk factor that causes exacerbations of
asthma; a stimulus that causes an increase in asthma symptoms and/or airflow
limitation.
Zone system
- An asthma management system based on
specified levels of symptoms and PEF that helps patients monitor their disease,
identify the earliest possible signs that the day-to-day control of asthma is
deteriorating, and act quickly to regain control. Typically, the system mimics a
traffic light, with green (all clear), yellow (caution) and red (danger) zones.
A patient management plan based on a zone system describes medications,
environmental control measures and contact with a health care professional for
each zone.
Adapted from the Global Initiative for
Asthma, National Heart, Lung and Blood Institute, National Institutes of Health
and The World Health Organization (1995) and The American College of Allergy,
Asthma & Immunology (1996).
© Copyright 1997 American
Medical Association
Other pages in this
section:
Asthma
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