Asthma is an obstructive airway disease that is reversible. It is characterized by hyper-responsiveness of the airways, resulting in chronic inflammation and bronchospasm. Chronic bronchitis and emphysema are other examples of obstructive airway diseases that are reversible. (CH, 2011) Asthma can either be extrinsic, also known as atopic asthma, or intrinsic, which is also called non-atopic asthma. Extrinsic asthma is the more common variety, comprising of about seventy percent of all cases. This type of asthma is actually an allergic response to a stimulus. The stimulus can vary from person to person. The allergic response can have two phases, namely, an acute response and a late response. The acute response occurs immediately and is mediated through sub-epithelial vagal receptors that cause bronchospasm. This results in a narrow airway through which air must pass to reach the terminal alveoli. The resulting obstruction can worsen with the late response. The late response occurs in the next twenty four hours and is mediated by inflammatory cells which release cytokines. These cytokines cause inflammation and also stimulate the production of mucous. (Kumar, Cotran & Robbins, 2005)

The other variety, called intrinsic asthma is caused by viruses, pulmonary infections, inhaled irritants, aspirin, exercise and stress. The underlying pathophysiology regarding airway obstruction is similar. Individuals with extrinsic asthma who already have underlying atopic asthma develop a more sustained and severe attack. (Kumar, Cotran & Robbins, 2005)

Asthma can complicate into status asthmaticus. This condition is characterized by severe paroxysms that remain for days or weeks and are irresponsive to treatment. Patients develop a classic triad of hypercapnea, acidosis and severe hypoxia. (Kumar, Cotran & Robbins, 2005)

Most patients with asthma have a positive family history for asthma or other atopic disorders. This provides evidence to a genetic association of the disease. Other environmental factors...

Aspirin inhibits certain enzymes that decrease inflammation. Certain upper airway infections and cold weather also trigger an asthmatic attack. ("Asthma attack," 2011)
The signs and symptoms of asthma are related to decreased air entry into the terminal airways. This stimulates the hypoxic centers in the brain to increase the work of breathing. Asthmatics, therefore, have to use extra muscles to increase this work. As a patient labors to inspire, the air produces a characteristic whistling sound, called wheezing. The cough reflex is also stimulated to expel the excess mucous produced by the airways. Patients also experience chest tightness and sometimes even chest pain during attacks. These symptoms are characteristic of asthma, especially if they worsen at night. ("Asthma attack," 2011)

Another characteristic feature of asthma is a reduced Forced Expiratory Volume to the Forced Vital Capacity ratio, FEV: FVC. This is measured through a spirometer which is the test of choice for obstructive airway diseases. Obstruction in the airways causes most of the inspired air to be trapped in the lungs, decreasing the expiratory volume. Other tests include challenge tests, such as exercise tests to see the development of airway obstruction. Chest X-ray and igE assays are not routinely indicated. Pulse oximetry is used to check the level of hypoxia. Hypoxia greater than ninety two percent requires regular Arterial Blood Gas monitoring for the development of danger signs. Sometimes, Chest X-rays are needed to rule out other lung pathologies, for example, emphysema or bronchiolitis. If a patient complains of shortness of breath along with fever, a Complete Blood Count (CBC) may also be needed to check for the presence of infection. ("Asthma: Steps in," 2011)

Asthma can be classified upon different grades of severity depending on certain factors. These factors include, frequency of exacerbations, the number of times a patient feels the need to use a short acting…