Asthma is a common disorder that primarily involves the airways. Traditionally, asthma has been considered a disorder of airway smooth muscle mediators and anatomic elements of the airway mucosa. In recent years, the roles of immune mediators, such as leukotrienes, prostaglandins, and platelet-activating factor, and the more traditionally considered roles of histamine and other bronchoconstrictors have been increasingly understood. Although the causes of asthma are separated into allergic and nonallergic ones, considerable crossover is observed in the features of both types of asthma, and treatment varies little between them. While asthma has been considered a disorder of the airways, a number of conditions have a presentation similar to that of bronchial asthma. These conditions originate, often silently, in organ systems other than the lungs, and they either provoke airway responses equivalent to those found in asthma or mimic the clinical findings of asthma. Body
Bronchial Asthma is a chronic condition involving the respiratory system in which the airways occasionally constrict, become inflamed, and are lined with excessive amounts of mucus, often in response to one or more triggers. This disease is caused by increased responsiveness of the tracheobronchial tree to various stimuli. The result is paroxysmal constriction of the bronchial airways. Bronchial asthma is the more correct name for the common form of asthma. The term 'bronchial' is used to differentiate it from 'cardiac' asthma, which is a separate condition that is caused by the heart failure. These episodes may be triggered by such things as exposure to an environmental stimulant such as an allergen, environmental tobacco smoke, cold or warm air, perfume, pet dander, moist air, exercise or exertion, or emotional stress. In children, the most common triggers are viral illnesses such as those that cause the common cold. This airway narrowing causes symptoms such as wheezing, shortness of breath, chest tightness, and coughing. The airway constriction responds to bronchodilators. Between episodes, most patients feel well but can have mild symptoms and they may remain short of breath after exercise for longer periods of time than the unaffected individual. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of drugs and environmental changes. Epidemiology
Undoubtedly, asthma is a very common condition and currently, according to Asthma UK. •5.2 million people in the UK receive treatment for asthma: 1 in 10 children and 1 in 12 adults. •It is the commonest chronic medical condition in children. •There are 4.1 million GP consultations for asthma per year. •The cost of asthma to the NHS runs at about a billion pounds per year. •Internationally, the UK is one of the highest ranking countries in terms of asthma prevalence, hospital admissions and mortality. •Peak prevalence occurs between 5 and 15, and falls thereafter until 55 to 64 years old when it starts to rise again. •Gender differences - there is a male preponderance in childhood with a reversal in early adulthood. •Certain trends in the prevalence of asthma seem apparent over time, but their interpretation is difficult, given methodological difficulties (variation in methods of data collection and classification) as well as cultural artefact from changes in the way patients describe respiratory symptoms and the 'ease' with which doctors apply the diagnosis. •Asthma diagnoses have become much more common since the 1950s, with childhood prevalence increased by two to three times. The trend in childhood prevalence appears to have flattened or even fallen recently whilst it remains plateaued in adults. •Incidence (based on new asthma diagnoses from the GP) has risen in all ages to a plateau in the 1990s and subsequently fallen. •Hospital admission rates rose from the 1960s to the late 1980s and are now...