Asthma is defined as a chronic respiratory disease characterised by episodes of acute airflow obstruction, increased mucous production, bronchial hypersensitivity and airway inflammation caused by a cascade of conditions and interactions. Each of the mentioned interactions is influenced to a great extent by the internal physiologic environment and external factors. The wheezing and shortness of breath experienced by an individual during an asthmatic attack are a result of physiologic interactions. The attacks are triggered by airway irritants such as cigarette smoke, allergens, and environmental pollutants. (Clark 2011, p.15-16).
History of Asthma:
The history of asthma is as old as antiquity. This statement can be justified by the fact that prescriptions for asthmatic patients written in hieroglyphics were found in the Egyptian Ebers Papyrus which was discovered in the 1870s. Such prescriptions included formulations of inhalations which contained mixtures of herbs intended to be heated on a brick in order to generate fumes which were to be inhaled by the patient. The Greek word azein means “-to breathe hard-” and the word asthma is derived from azein. Therefore, the literal meaning of asthma is a condition characterized by difficult breathing. (Clark 2011, p.1-2).
Asthma is a chronic respiratory disease and its severity ranges from severe occasional symptoms to persistent symptoms. It is one of the most common chronic diseases of children with a global prevalence of about 5%. The incidence rates of asthma can be as high as 20% in developed countries. The disease is more in developed countries than in developing countries. Recent statistics show that the incidence rate of asthma is steadily increasing both in developed and developing countries. The development of new treatment and management strategies has unfortunately had no significant effect on reducing the mortality rates associated with asthma. (Gershwin & Albertson 2008, p.232). The prevalence of asthma in the United States of America in 2009 was 8.2% that is 24.6 million individuals. A survey of patient subgroups revealed that the prevalence of asthma was more common in females compared to males. Furthermore, the National Health Statistics Reports 2005-2009 (Atkinson, Moorman & Xiang Liu 2011) reveal a higher prevalence of asthma in children, individuals of non-Hispanic Black and Puerto Rican race or ethnicity, and persons with a family income below the average poverty line. A higher prevalence was also observed in individuals residing in Northeast and Midwestern regions. Due to asthma, a total of 10.5 million school days and 14.2 million work days were missed in 2008 alone. The 2007 statistics reveal that a total of 1.75 million visits to emergency departments were related to asthma. Moreover, the 2007 statistics reveal that 456,000 asthma related hospitalisations were reported. (Akinbami, Moorman, & Liu 2011, pg.1). Etiology: The etiology of asthma is difficult to define because it is a heterogeneous disease governed by genetic and environmental factors. The non specific hyperirritability of the tracheobronchial tree is the most common underlying characteristic of asthmatic diathesis. Asthma is divided into two major types on clinical basis: allergic (extrinsic) and idiosyncratic (intrinsic). The development of allergic asthma is mediated by genetic factors due to which the individual’s susceptibility to precipitating factors and extracts of airborne antigens is increased. The major characteristic of allergic asthma is high serum level of immunoglobulin E (IgE). In 25 to 30% of all allergic asthma cases, the immunologic mechanisms are casually related, whereas in 33% of cases the immunologic mechanisms are contributory. An asthmatic attack is precipitated by agents that stimulate the receptors present on the surfaces of tracheobronchial receptors. Cholinergic mediation is responsible for the development of intraoperative