Glossary of Asthma
Many terms are used to describe asthma and asthma management. This chapter attempts to simplify the technical language by selecting key words that reflect our current understanding of asthma. Included in this glossary are those words that need to be defined precisely so that their meaning may be clearly understood and not.
Acute - Brief period (days to weeks).
Airflow limitation - A prolonged forced expiratory time (i.e.,longer than 4 seconds)."Airflow limitation" replaces 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.
Anti-inflammatory - Inhibiting one or more of the components of the inflammatory reaction.
Working definition: Asthma is a chronic inflammatory disorder in which many cells play a role, in particular mast cells, eosinophils, and T Lymphocytes.In susceptible indeviduals 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 “ever wheeze” - occurance of wheeze during any time of life (the least useful data because of medical certification). “Doctor diagnosed asthma” - certified as asthmatic by a medical practitioner (more valuable because of medical certification) “Current asthma” - 3 attacks of asthma within the past year associated with clinical features of hyperresponsiveness to multiple stimuli.
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 followup care.
Atopy - The propensity, usually genetic, for developing lgE-mediated responses to common environmental allergens.
Brittle asthma - Patients with asthma who present with a wide variation of peak expiratory flow rate (PEFR) despite high dose of inhaled steroid. They are of two types.
Type-I : Characterised by wide PEFR variability (> 40% Diurnal variation for > 50% of the time over a period of at least 150 days) despite considerable medical therapy including a dose of inhaled steroids of at least 1500 mcg of Beclomethasone or equivalent.
Type-II : Characterised by sudden acute attacks occuring in less than 3 hours without an obvious trigger on a background of apparent normal airway function or well controlled asthma.
Bronchoconstriction - Airflow limitation due to contraction of airway smooth muscle. “Bronchoconstriction” replaces the word “bronchospasm.”
Causal factors - Risk factors that sensitize the airways and cause the onset of asthma. The most important of these factors are allergens.
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, small size at birth, and environmental pollutants.
Disorder versus disease - Disorder implies a health condition with multiple 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 (caution) - Removal of risk factors from the environment.
Exacerbate - To aggravate or make asthma worse. “Exacerbate” replaces the words “cause,” “precipitate,” “induce,” and “incite.”
Exacerbation - Any worsening of asthma. Onset can be acute and sudden, o4r gradual over serval days. A correlation between symptoms and peak flow is not necessarily found. “Exacerbation” replaces the words “attack” and “episode.”
Guided self-management - Providing the patient and his or her family 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 in care for sick people, e.g. specialist doctors, physicians, nurses, health educator.
Irritant - Risk factor or trigger that may cause increased symptoms and/or airflow limitation via a neural pathway.
Medication plan - A specific plan, preferably written (or pictorial for low-literacy populations), to achieve and maintain control of asthma based on use of preventer and reliever medications in a stepwise approach. A medication plan also includes instructions on how to recorgnize 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.
PEFR (Peak Expiratory Flow Rate) home monitoring - Measurement of PEFR on a regular basis at home with a portable peak flow meter. PEFR home monitoring is especially useful to patients over 5 years of age with moderate persistent to severe persistent asthma.
PEFR variability - diurnal variation in peak flow expressed as the formula.
Diurnal variability = (Highest PEFR - Lowest PEFR ) x 100/ Highest PEFR
Calculations of PEFR daily variability provide a reasonable index of asthma stability and severity.
Preventer medications - Medications taken daily on a long-term basis that are useful in getting persistent asthma under control and in maintaining control. They are anti-inflammatory agents e.g. cromones, corticosteroids. Anti-inflammatory agents, particularly inhaled corticosteroids, are at present the most effective preventer medications.
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. Protector medications - Long acting bronchodilators, e.g. slow releasing Aminophylline, sustain releasing Salbutamol, are known as protectors. 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: 1. 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.” 2. Risk factors that cause asthma exacerbations in individuals who already have the condition. These are also called triggers.
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. The aim is to accomplish the goals of therapy with the least possible medication.
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 deterorating, and act quickly to regain control. A management plan based on a zone system is developed for a patient that describes medications, environmental control measures and contact with the health care professional for each zone.
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