It is very highly prevalent disease in the United Kingdom. According to statistics, the current number of patients in the United Kingdom is 5.1 million. This number has increased from the previous study. About 8% adults and 13% children are affected, and this increased trend has been postulated to be due to a combination of genetic, environmental, and population growth factors. There is a number of emergency hospital admission and death due to this disease (SIGN and BTS 2009).
Asthma is heterogeneous in terms of aetiology. Atopy is a common cause, and genetic factors are involved in transmission of these atopic traits. Some environmental factors which the individual may be exposed in the domestic or occupational environments may also trigger asthma. These are viruses, allergens, dust mites and others. These also contribute to asthma trigger and continuance of the disease. The most important risk factor is allergic diathesis or atopy. In many cases, no such links have been described (Satta, 2000).
Asthma leads to subacute inflammation of the airways. The persistent nature of this inflammation leads to oedema of mucous membranes. With inflammation, the inflammatory cells infiltrate the mucosa. This also leads to increased congestion in the blood vessels due to slowing of circulation. With the external triggering agent, the inflammatory cells accumulated in the mucosal epithelium which release inflammatory mediators leading to amplification of the basic inflammatory process, which culminates into an intense and immediate inflammatory reaction leading to constriction of airways, vascular congestion, oedema, increased mucus production, and inability expectorate due to impaired mucociliary transport. These events are followed by a chronic inflammatory stage giving the disease a characteristic acute, chronic, and acute-on-chronic picture (Nici et al, 2006).
Cough, dyspnoea, and wheezing are the main symptoms. Typically, in most cases, all these three symptoms are encountered. The cough is nonproductive. The dyspnoea is associated with generalised constriction of the airways, which leads to an associated sense of constriction while breathing. The airway resistance increases leading to harsh breath sounds that can be heart without any hearing aids. In the phases of both inspiration and exhalation, wheezing is prominently heard. Moreover there is difficulty in passive air passage in expiration. With a prolonged expiration, air is trapped, and this increases the drive of breathing due to hypercapnia and hypoxemia. These in turn lead to tachypnoea, systolic hypertension or mild grade, and a compensatory tachycardia. With air trapping, the lungs keep on gathering air, are inflated, and the thoracic diameter increases anteroposteriorly. With the impairment of pulmonary function, the breathing is laborious despite which the patient becomes hypoxaemic (MacNee, 2008).
For assessment, the physical exertion is assessed, and the amount is less than that required to produce asthma symptoms. This is usually equivalent to relative work rate of 75% of age-predicted maximal heart rate.
A pre-prescription assessment must include a detailed history and clinical assessment. The history of medications, inhalation