What is Asthma
is defined as a disorder characterized by chronic airway inflammation and increased
airway responsiveness resulting in symptoms of wheeze, cough chest tightness and
It is not a uniform disease but rather a dynamic clinical syndrome, which has a number of clinical patterns. Many patients with well-controlled asthma are asymptomatic.
With normal lung function between exacerbations although even these patients have evidence of chronic airway inflammation and hyper responsiveness.
By contrast, in some patients with chronic asthma the asthma progresses leading to irreversible obstruction of the airways.Asthma is a disease of airways that is characterized by increased responsiveness of the tracheobronchial tree to a multiplicity of stimuli.
Asthma is manifested physiologically by a widespread narrowing of the air passages, which may be relieved spontaneously or as a result of therapy, and clinically by paroxysms of dyspnoea, cough and wheezing.
It is an episodic disease, acute exacerbations being interspersed with symptoms free periods. Typically most attacks are short lived, lasting minutes to hours, and after them the patient seems to recover completely clinically.
However there can be a phase in which the patient experiences some degree of airway obstruction daily. This phase can be mild, with or without superimposed severe episodes, or much more serious.
With severe obstruction persisting for days or weeks a condition known as status asthamaticus. In unusual circumstances, acute episodes can terminate fatally.
Prevalence and Etiology:
Asthma is a very common disorder, and it is estimated that 4 5 percent of the population of the United States is affected. Similar figures have been reported from other countries.
Bronchial asthma occurs at all ages but predominantly in early life. About one half of the cases develop before aged 10 and another thirds occur before age 40. In childhood, there is a 2:1 male / female preponderance, which equalizes by age 30.
From an etiologic standpoint, asthma is a heterogeneous disease. It is useful for epidemiologic and clinical purposes to classify asthma by the principal stimuli that incite or are associated with acute episodes.
However, it is important to emphasize that this distinction may often be artificial, and the response of a given sub classification usually can be initiated by more than one type of stimulus. With this reservation in mind, one can describe two broad groups, allergic and idiosyncratic.
Allertic asthma is often associated with a personal and family history of allergic diseases such as rhinitis, urticaria and eczema, positive wheal and flare skin reactions to intradermal injection of extracts or airborne antigens, increased levels of IgE in the serum, and positive response to provocation tests involving the inhalation of specific antigen.
A significant segment of the asthmatic population will present with negative family or personal histories of allergy, negative skin tests, and normal serum levels of IgE and therefore cannot be classified on the basis of defined Immunologic mechanisms.
These we term idiosyncratic. Many of these will develop a typical symptom complex upon contracting an upper respiratory illness. The initial insult may be a little more than a common cold, but after several days the patient begins to develop paroxysms of wheezing and dyspnoea that can last for days to months.
These individuals should not be confused with persons in whom the symptoms of bronchospasm are superimposed on chronic bronchitis or bronchiectasis.
Unfortunately many patients will not clearly fit into either of the preceding categories but will fall into a mixed group with features of each.
general, those patients whose onset of disease is in early life will tend to have
a strong allergic component to their illness, while those who develop their asthma
late tend to be non allergic or to have mixed etiologies.
| Management of Asthma | Cardinal features of Asthma | Importance of immediate assessment of acute severe asthma | Simple Investigation process involved in bronchial asthma | What is pathio-physiological treatment in bronchial asthma | Prevalence in Bronchial Asthma | Symptoms & Clinical features in bronchial asthma |
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