Asthma is a disease of the bronchial tubes, or airways, of the lungs that makes breathing difficult. Symptoms include frequent coughing-especially at night, shortness of breath, wheezing, and chest tightness, pain, or pressure. Asthma attacks can be triggered by infections such as colds or the flu, exercise, cold weather, tobacco smoke, air pollution, allergens, and chemical odors.
Asthma is one of the most common chronic diseases. About one third of those affected are children under age 18. Asthma may occur at any age, although a first attack is more likely to occur before the age of 40.
No one knows exactly what causes asthma, and a cure remains elusive. But in recent years, great strides have been made in developing new treatments so that people with asthma can successfully manage the disease themselves, reducing symptoms and maintaining an active, satisfying life.
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Asthma is a disease of the bronchial tubes, the airways of the lungs. When air is taken into the body through the nose and windpipe, it passes through the bronchial tubes and smaller bronchioles into tiny air sacs, called alveoli, that deliver oxygen to the blood. The air sacs also collect carbon dioxide from the blood, which is then exhaled.
During normal breathing, the bands of muscle that surround the airways are relaxed, and air moves freely. During an asthma episode, or "attack," three main changes stop air from moving easily through the airways:
Bronchospasms, inflammation, and mucus production cause asthma symptoms, which include wheezing, coughing, breathlessness, chest pressure, pain, or tightness. Severe episodes can lead to inability to perform normal activities like walking and talking.
The airways in a person with asthma are very sensitive and react to many "triggers," although doctors don't know exactly why the triggers bring on asthma symptoms. People react differently to the various triggers, and an individual's reaction can vary from episode to episode. One of the most important steps in asthma control is avoiding triggers.
Common asthma triggers include the following:
The number of people with asthma is on the rise, with more than 17 million Americans affected. More than 5 million of those are children. Although the exact causes of asthma are unknown, scientists have identified risk factors that make it more likely that a person will have asthma. They include the following:
Occupational asthma is caused or aggravated by exposure to substances in the workplace. For example, healthcare workers can develop an allergic reaction to latex gloves by breathing in the powdered proteins from the inner lining of the gloves. Workers in the chemical industry who are exposed to substances like ammonia can develop asthma due to irritation.
Exposure to many substances used in industries can cause occupational asthma:
If asthma is caused by occupational exposure, the symptoms usually are worse on workdays and improve when you are at home for any length of time. Symptoms include coughing, wheezing, chest tightness, and shortness of breath. Eye irritation, nasal congestion and a runny nose may also be present.
If you think you have occupational asthma, ask your doctor about a referral to a specialist, most likely an allergist.
Sinusitis is inflammation of the nasal passages around the nose and eyes. These passages are called sinuses. The sinuses warm, filter, and moisten air as we breathe. Symptoms of sinusitis include thick, colored drainage from the nose, coughing, post-nasal drip that may taste bad, headache, and head congestion, as well as a feeling of facial fullness or swelling, tooth pain, and sometimes fever.
Sinusitis and asthma frequently coexist. When present, sinusitis can make asthma harder to treat. Remember that asthma is inflammation of the lungs and sinusitis is inflammation of the nasal passages. Controlling the inflammatory process in the nose can help lead to better control of asthma symptoms.
Treatment of sinusitis includes use of anti-inflammatory nasal sprays (steroid nasal sprays) as well as antihistamine and decongestant medications. If the sinuses become infected, appropriate antibiotic therapy will be prescribed to treat the infection.
It is estimated that more than 75 percent of patients with asthma also experience gastroesophageal reflux disease (GERD), the backward flow of stomach acids into the esophagus. People with asthma are twice as likely to have GERD as people without the condition-and those who have a severe, chronic form that is resistant to treatment are most likely to also have GERD.
When acid enters the lower part of the esophagus, it can produce a burning sensation, or heartburn. If left untreated, GERD can eventually lead to lung damage, esophageal ulcers, and in some instances Barrett's esophagus, a condition that can eventually result in esophageal cancer.
Doctors most often look at GERD as the cause of asthma when the following happen:
Why do GERD and asthma coincide? One possible explanation is that the acid flow causes injury to the lining of the throat, airways, and lungs, making inhalation difficult and causing a persistent cough. Another possibility is that when acid enters the esophagus, a nerve reflex is triggered that causes the airways to narrow in order to prevent more acid from entering. This will cause shortness of breath. One study showed an increase in the rate of GERD in asthma patients treated with medications known as beta-adrenergic bronchodilators. However, further studies must be done before the relationship between GERD and these drugs can be understood.
If you have both asthma and GERD, it is important that you consistently take any asthma medications your doctor has prescribed and that you control your exposure to asthma triggers as much as possible.
To control symptoms of GERD, you should:
Asthma is divided into four types, based on the frequency of symptoms as well as lung-function studies. Your physician will determine the severity of your asthma based on this information. A person's asthma can jump from one classification to another from day to day.
Mild, intermittent asthma
Mild, persistent asthma
Moderate, persistent asthma
Severe, persistent asthma
Though asthma cannot be cured, it can be controlled. Frequent symptoms, trouble sleeping, difficulty completing tasks, and trips to the emergency room can be avoided with preventive steps and appropriate treatment.
Last reviewed on 8/26/08
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