Asthma is a chronic, inflammatory lung disease involving recurrent breathing problems. The characteristics of asthma are three airway problems:
Asthma may resemble other respiratory problems, such as emphysema, bronchitis, and lower respiratory infections. It is underdiagnosed--many people with the disease do not know they have it. Sometimes the only symptom is a chronic cough, especially at night, chest tightness, noisy breathing, or wheezing. Some people think they have recurrent bronchitis, since respiratory infections usually settle in the chest in a person predisposed to asthma.
The basic cause of the lung abnormality in asthma is not yet known, although health care professionals have established that it is a special type of inflammation of the airway that leads to:
- Constriction and irritability of airway muscles
- Mucus production
- Swelling in the airways
It is important to know that asthma is not caused by emotional factors as commonly believed years ago. Emotional anxiety and nervous stress can, however, directly affect your immune and respiratory systems and increase asthma symptoms or aggravate an attack. These reactions are considered to be more of an effect than a cause.
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.
The number of people in the U.S. who have asthma is rising. Although the exact cause is unknown, several theories have been proposed as to why. One of the most common is the "hygiene hypothesis," which suggests that living in too clean an environment prevents exposure to germs that stimulate the immune system. Scientists believe that an underutilized immune system may overreact to lesser irritants, inappropriately triggering the release of histamine and other inflammatory substances in the lungs.
Other researchers believe that a variety of factors may be contributing. These include rising obesity rates and increased use of antibiotics.
Although anyone may have an asthma attack, it most commonly occurs in:
- Children and adolescents ages 5 to 17 years
- People living in urban communities
Other factors include:
- 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
- Infants and other young children who develop a respiratory infection also tend to have wheezing
- Children who have allergies
- Children who are exposed to tobacco smoke
People with asthma have acute episodes when the air passages in their lungs get narrower, and breathing becomes more difficult. These problems are caused by an oversensitivity of the lungs and airways.
- Lungs and airways overreact to certain triggers and become inflamed and clogged.
- 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:
- Muscles that surround the airways tighten, the inner lining of the airways swells and pushes inward.
- Membranes that line the airways secrete extra mucus.
- The mucus can form plugs that further block the air passages.
- The rush of air through the narrowed airways produces the wheezing sounds.
To diagnose asthma and distinguish it from other lung disorders, doctors rely on a combination of medical history, physical examination, and laboratory tests, which may include:
- Spirometry. A spirometer is a device used by your doctor that assesses lung function. Spirometry is the evaluation of lung function with a spirometer. The test is performed by blowing as hard as possible into a tube connected to a small machine (a spirometer) that measures the amount of air breathed out and in as well as the speed it is breathed out. This is one of the simplest, most common pulmonary function tests and may be necessary for any or 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. To use a peak flow meter, a person takes a deep breath in and then blows as hard and fast as possible into a mouthpiece. 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-ray. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- Blood tests. Tests to analyze the amount of carbon dioxide and oxygen in the blood.
- Allergy tests
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