Asthma is a chronic, inflammatory disease in which the airways become sensitive to allergens (any substance that triggers an allergic reaction). Several things happen to the airways when a person is exposed to certain triggers:
- The lining of the airways becomes swollen and inflamed.
- The muscles that surround the airways tighten.
- The production of mucus is increased, leading to mucus plugs.
All of these factors will cause the airways to narrow, thus making it difficult for air to go in and out of your lungs, causing the symptoms of asthma.
Asthma may resemble other respiratory problems such as emphysema, bronchitis, and lower respiratory infections. It is often under-diagnosed and many people with the disease do not know they have it. Sometimes, the only symptom is a chronic cough, especially at night, or coughing or wheezing that occurs only with exercise. Some people think they have recurrent bronchitis, since respiratory infections usually settle in the chest in a person predisposed to asthma.
The exact cause of asthma is not completely known. It is believed to be partially inherited, but it also involves many other environmental, infectious, and chemical factors. After a person is exposed to a certain trigger, the body releases histamine and other agents that can cause inflammation in the airways. The body also releases other factors that can cause the muscles of the airways to tighten, or become smaller. There is also an increase in mucus production that may clog the airways.
Some persons have exercise-induced asthma, which is caused by varying degrees of exercise. Symptoms can occur during, or shortly after, exercise. Each person has different triggers that cause the asthma to worsen. You should discuss this with your physician.
The changes that occur in asthma are believed to happen in two phases:
- An immediate response to the trigger leads to swelling and narrowing of the airways. This makes it initially difficult to breathe.
- A later response, which can happen four to eight hours after the initial exposure to the allergen, leads to further inflammation of the airways and obstruction of airflow.
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, diet, family history, or many other things.
Different diseases have different risk factors. Although these factors can increase a person's risk, they do not necessarily cause the disease. For example, some people with one or more risk factors never develop cancer, while others develop cancer and have no known risk factors.
Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
Although anyone may have an asthma attack, it most commonly occurs in the following persons:
- children and adolescents ages 5 to17
- adults older than 65
- people living in urban communities
Other factors include the following:
- family history of asthma
- personal medical history of allergies
Children most susceptible to asthma attacks include the following:
- children with a family history of asthma
- children who have allergies
- children who have exposure to secondhand tobacco smoke
Persons with asthma have acute episodes when the air passages in their lungs become narrower, and breathing becomes more difficult. These problems are caused by an over-sensitivity of the lungs and airways.
- The lungs and airways overreact to certain triggers causing:
- the lining of the airways to become inflamed and swollen.
- tightening of the muscles that surround the airways.
- an increased production of mucus.
- Breathing becomes harder and may hurt.
- There may be coughing.
- There may be a wheezing or whistling sound, which is typical of asthma. Wheezing occurs because of the rush of air which moves through the narrowed airways.
To diagnose asthma and distinguish it from other lung disorders, physicians rely on a combination of medical history, physical examination, and laboratory tests, which may include the following:
- spirometry - a spirometer is a device used by your physician that assesses lung function. Spirometry, the evaluation of lung function with a spirometer, is one of the simplest, most common pulmonary function tests and may be necessary for any/all of the following reasons:
- to determine how well the lungs receive, hold, and utilize air
- to monitor a lung disease
- to monitor the effectiveness of treatment
- to determine the severity of a lung disease
- to determine whether the lung disease is restrictive (decreased airflow) or obstructive (disruption of airflow)
- peak flow monitoring (PFM) - a device used to measure the fastest speed in which a person can blow air out of the lungs. During an asthma or other respiratory flare up, the large airways in the lungs slowly begin to narrow. This will slow the speed of air leaving the lungs and can be measured by a PFM. This measurement is very important in evaluating how well or how poorly the disease is being controlled.
- chest x-rays - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- blood tests - to analyze the amount of carbon dioxide and oxygen in the blood.
According to the National Institute for Allergy and Infectious Diseases, the American Academy of Allergy, Asthma, and Immunology, and other organizations, triggers for asthma include the following:
||Respiratory Infections and Sinusitis
- animal protein (dander, urine, oil from skin)
- house dust/dust mites
- certain foods
Infections can cause irritation of the airways, nose, throat, lungs, and sinuses, and worsens asthma.
||Sensitivity to Medications
- strong odors and sprays, such as perfumes, household cleaners, cooking fumes, paints, and varnishes
- chemicals such as coal, chalk dust, or talcum powder
- air pollutants
- changing weather conditions, including changes in temperature, barometric pressure, humidity, and strong winds
- Chemical exposure on the job, such as occupational vapors, dust, gases, or fumes.
Medications such as aspirin and additives such as sulfites, cause up to 20 percent of adult asthmatic attacks as a result of sensitivities or allergies to them. These medications often include:
- other non-steroidal anti-inflammatory medications, such as ibuprofen, indomethacin, naproxen
- sulfites used as preservatives in food and beverage
Before taking any medication, including over-the-counter medications, consult your physician.
Exercise can trigger an asthma attack, often because of the inhaled cool and dry air. Long-term strenuous activities such as long distance running, are most likely to induce asthma, and swimming is the least likely.
GERD, a condition characterized by persistent reflux of stomach acids, is common in individuals with asthma. Symptoms may include heartburn, belching, or spitting up in infants.
||Emotional Anxiety and Nervous Stress
Tobacco smoke, whether directly or passively inhaled, has been shown to worsen asthma.
Wood smoke from wood-burning heating stoves and fireplaces can release irritating chemicals such as sulfur dioxide.
Reactions from stress and anxiety are considered to be more of an effect than a cause. They can cause fatigue, which may affect the immune system and, in turn, increase either asthma symptoms or bring on an attack.
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