Asthma is a chronic inflammation of the airways causing swelling and narrowing. This leads to breathing difficulty. This narrowing of airways almost often can be totally or partially reversed with treatments.
The airways (bronchial tubes) that are chronically inflamed sometimes become over sensitive to allergens or irritants. The airways may remain in a state of heightened sensitivity. This is called "Bronchial Hyperreactivity". Asthmatics and allergic individuals(without apparent asthma) have a greater degree of bronchial hyperractivity than non-asthmatic and nonallergic people. In sensitive individuals, the bronchial tubes are more likely to swell and constrict when exposed allergens, tobacco smoke, or exercise. Asthma affects people differently. Each individual is unique in their degree of reactivity to environmental triggers.
Asthma is a problem world wide with an estimated 300 million affected individuals. Asthma is now one of the mos common chronic illnesses in children,affecting one in ever 15. There are about 5,000 deaths annually from asthma in the U.S. and about 500 deaths per year in Canada.
Asthma narrows of the breathing airways,which obstructs the normal movement of air in and out of the lungs.It involves only the bronchial tubes and does not affect the air sacs or the lung tissue.The narrowing is caused by three major changes namely inflammation,bronchospasm,and hyperreactivity.
Inflammation is the most important factor causing narrowing of the bronchial tubes. The bronchial tubes become red, irritated, and swollen.The inflammation occurs in response to an allergen or irritant. The inflamed tissues produce an excess amount of "sticky" mucus into the tubes,which can clump together and form "plugs" that can obstruct the smaller airways,causing tissue damage. These damaged cells are shed into the airways, thereby narrowing them.
Bronchospasm is the tightening of the smooth muscles around the bronchial tubes during an attack of asthma. This causes the airway to narrow further. Chemical mediators and nerves in the bronchial tubes cause the nuscles to contract.
In asthmatic patients, the chronically inflamed and constricted airways become highly sensitive to allergens, irritantts, and infections, especially viral. Exposure to these may result in progressively more inflammation and narrowing.
These three factors combined result in difficulty with breathing out.Consequently the air has to be forcefully exhaled to overcome the narrowing, thereby causing the typical "wheezing" sound.
The key to managing asthma is the prevention and treatment of airway inflammmation.
Asthma symptoms may be initiated or worsened by many agents. All asthmatics do not react to the same tiggers. Also, the effect of each trigger on the lungs varies from one individual to another. Generally, the severity of asthma depends on the number of agents activating the symptoms and the sensitivity of the lungs to them. Most of these triggers can also worsen nasal or eye symptoms.
Triggers can be Allergens or Non-allergens that are mostly irritants.Common Asthma Triggers are Allergens like pollens from flowers (usually seasonal), insects, pets, mites, molds, certain types of food, latex etc. Around 80% childern and 50% adults with asthma have allergies too. Irritants may include viral colds, bronchitis, sinusitis, drugs, tobacco smoke,smog, weather changes diesel fumes, paint, detergents, deodorants, chemicals, perfumes, night-time, exercise, dust,metals, laughing, crying, yelling and hormonal factors.
Symptoms of asthma may vary from individual to individual and in any individual from time to time. Many of the symptoms can be subtle and similar to those seen in other conditions. The major recognized symptoms are :
Prolonged attacks of asthma that do not respond to treatment are a medical emergency. These severe attacks require immediate emergency care. Extremely severe attacks may clog the tubes to such an extent that the lack of air in and out of your lungs fails to produce wheezing or coughing, which could lead to respiratory failure and death.