About asthma
A person with asthma experiences inflammation of the bronchial tubes, even when symptoms are not present. This causes a narrowing of the airways and an increased sensitivity to allergens or other stimuli. Exposure to these triggers often produces symptoms such as coughing, wheezing and an inability to breathe normally (shortness of breath).
Asthma primarily affects the bronchi, the large passageways that allow air to
During an asthma attack, exposure to an allergen or other stimuli (such as exercise or cold air) causes mast cells in the tissue of an asthmatic’s air passages to react by producing histamine, leukotrienes and other chemicals. These chemicals cause the following chain reactions:
- The smooth muscle of the bronchi goes into bronchospasm and tightens, constricting the airways.
- The tissues lining the airways – which are often inflamed in asthmatics – become further inflamed, further narrowing the airways.
- The inflamed tissues produce excess mucus that fills and obstructs the airways.
The combination of smooth–muscle constriction, tissue inflammation and
mucus secretion significantly narrows the diameter of the airway, a process known as bronchoconstriction. When this happens, air is trapped in the lungs, forcing the individual to expend great effort to move air in and out.
Because airways are narrowed during an asthma attack, a person may experience chest tightness, coughing, wheezing and shortness of breath. In severe cases, where breathing becomes very difficult and low blood oxygen levels occur, asthma attacks can be fatal. About 5,000 deaths each year are attributed to asthma, according to the American Academy of Allergy, Asthma and Immunology (AAAAI).
Low blood oxygen levels can also be dangerous during pregnancy. Since a fetus depends on oxygen in the mother’s blood, uncontrolled asthma during pregnancy can lead to low birth weight and other complications
Someone suffering through an asthma attack may appear to be gasping for breath. But in fact, it is easier to breathe in during an asthma attack than it is to breathe out. As more air flows in, it becomes trapped in the lungs, which become overinflated. Asthmatics continue to try to push this ever–increasing amount of inhaled air out of their lungs and through a narrowed airway, usually with limited success.
According to the National Heart, Lung and Blood Institute, approximately 20 million people have been diagnosed with asthma, and 9 million of these patients are children. Asthma affects people of all ages. However, it often develops in childhood. The condition is more common in boys during childhood, but after puberty, more women have the condition.
Although asthma affects people of all races, African Americans are more likely to be hospitalized and die from the disease, when compared to Caucasians.
Types and differences of asthma
Asthma affects people in different ways and to various degrees. There are four levels of severity used to classify different types of asthma:
- Mild intermittent. Symptoms appear up to two days a week and two nights a month.
- Mild persistent. Symptoms appear more than two nights a month and more than twice a week, but not more than once in a single day.
- Moderate persistent. Symptoms occur every day and more than one night a week.
- Severe persistent. Symptoms occur continuously throughout the day and frequently at night.
Asthma is most commonly triggered by allergens, such as dander, pollens, dust and molds. But other stimuli also can trigger asthma symptoms or a full–blown asthma attack. Forms of asthma triggered by factors other than allergens include:
- Exercise-induced asthma (EIA). Asthma that occurs during vigorous physical activity. The condition usually manifests itself a few minutes after a person begins exercise. EIA afflicts a large percentage of asthmatics, and also can occur in individuals who usually have no other asthma symptoms.
- NSAID–sensitive asthma. Severe asthma attacks that occur as a result of taking nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin and ibuprofen. People with this condition should consult a physician, who may recommend an alternative pain reliever, such as one that contains acetaminophen.
- Nocturnal asthma. Asthma symptoms that manifest themselves primarily at night. It tends to occur between midnight and 8 a.m. and seems to be especially prevalent around 4 a.m. Triggers include:
- Typical allergens, such as dust and dander
- Airway secretions, such as mucus caused by sinusitis or postnasal drip
- Sleep apnea (abrupt halting of breathing), which may trigger reflexes that spark an asthma attack
- Lower levels of certain body chemicals, such as epinephrine and steroids
- Adult–onset asthma. Asthma that makes its first appearance in an adult after age 20. It is more common in women than in men.
- Occupational asthma. Asthma that is triggered by conditions in the workplace. The main triggers for occupational asthma are airborne contaminants or allergens and extremes in temperature or humidity levels. It is most likely to occur among those who work with animals or animal–based products and in industries such as food service (especially bakery), chemicals, electronics, gardening, metalworking, painting, printing, plastics, rubber and textiles.
Fortunately, there are medications and other strategies that can reverse the airway–narrowing process, allowing air to flow in and out of the body more easily.
- Mucous glands. These glands normally produce the proper amount of mucus to lubricate the airways. However, during an asthma attack they produce too much mucus, flooding and blocking the airways.
- Inflammatory cells. These cells (including mast cells, lymphocytes and eosinophils) trigger inflammation in response to something the body perceives as a threat, such as allergens or irritants. The inflammation, in turn, allows for more blood to flow to the area, carrying cells to fight the threat. This is a natural system designed to protect body tissue, such as the lining of the bronchial tubes (mucosa). However, during an asthma attack, the tissues remain inflamed for extended periods of time.
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