In patients of bronchial asthma the chemical mediators released due to allergen-antibody interaction, leads to narrowing of airways. A chronic inflammatory disease of the airways that causes periodic "attacks" of coughing, wheezing, shortness of breath, and chest tightness. Thus these patients suffer attacks of breathlessness. A wheezing sound appear due to the rush of air through narrowed airways. At the same time, a troublesome cough can also develop. Asthma may be allergic or non allergic. In patients of allergic asthma or in allergic rhinitis, environmental allergens, when inhaled precipitate symptoms.
Asthma is considered to be caused by a combination of genetic and environmental factors. Its diagnosis is usually based on the pattern of symptoms, response to therapy over time and spirometry. It is clinically classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic) where atopy refers to a predisposition toward developing type 1 hypersensitivity reactions.
Signs and symptoms of Asthma
Asthma is characterized by recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing, Sputum may be produced from the lung by coughing but is often hard to bring up. During recovery from an attack, it may appear pus-like due to high levels of white blood cells called eosinophils. Symptoms are usually worse at night and in the early morning or in response to exercise or cold air. Some people with asthma rarely experience symptoms, usually in response to triggers, whereas others may have marked and persistent symptoms.
- Air pollution
- Food additives
- Strong perfumes
- Cigarette smoke
- Some medicines eg: aspirin
- Respiratory infections
- Changes in temperature and humidity
- Psychological influences eg: extremes of emotion
- Workplace irritants eg: paint and varnish fumes, flour, wood dust.