Asthma

18 May

Asthma
Asthma affects the lining of the bronchi and the bronchioles. These airways become inflamed and produce extra mucus. Smooth muscle tissue in the airways contracts, narrowing the passageways even further. Common symptoms of asthma include wheezing (a faint whistling noise that occurs with each breath), shortness of breath, chest tightness (feeling as if someone is squeezing your chest), and coughing. Signs of an asthma emergency include extreme difficulty breathing, bluish tinge (cyanosis) to the lips and face, severe anxiety, rapid pulse, and sweating.

People who do not manage their asthma carefully often miss work, frequently require treatment in hospital emergency departments, or may die of a severe attack. During acute (sudden) attacks, the airways become significantly con- stricted (narrowed), very little air passes through to the alveoli, and oxygen lev- els in the blood decrease. Without an adequate supply of oxygen, tissues in the body begin to die. However, the risks can be significantly reduced with careful management of the disease.

Triggers of Asthma Attacks
S
pecific  substances,  conditions,  and  circum- stances can bring on an asthma attack in a per-
son who has asthma. An important strategy for controlling your asthma is to know and to avoid your specific triggers:

•   allergens—such as pollen, mold, animal dander (dead skin flakes) from household pets, and dust mite and cockroach droppings

• pollutants—such as tobacco smoke, wood smoke, smog, ozone, chemical fumes, dust, hair spray, perfume, and other sprays

•   foods and food additives—such as beer, wine, shrimp, milk, eggs, nuts, soy, wheat, dried fruit, and processed foods

•   weather  changes—such  as  cold  air,  strong winds, and sudden changes in barometric pres- sure or humidity

•   medications—such as aspirin, ibuprofen, and beta-blockers

•   physical exertion

•   viral infection or sinus infection

•   gastroesophageal reflux disease (see page 262)

•   anxiety

Controlling environmental factors that can trigger an asthma attack (see box on previous page) is only one step toward successful asthma management. Work closely with your doctor to establish an ongoing program to control your asthma. You will need to monitor your lung function daily with a peak flow meter (a device that measures the speed at which air can be forced from the lungs). This will help determine your response to treatment. Your physician also will check your lung function regularly with a device called a spirometer, which measures how much and how quickly air can be expelled after a deep breath, to monitor your condition and assess your response to treatment.

Medications used to treat asthma vary according to the individual and the tim- ing of administration. Avoid relying exclusively on short-term rescue medica- tions such as inhaled bronchodilators, which temporarily open up the bronchial tubes to increase air flow. Instead, work with your doctor to develop a long-term treatment plan that includes anti-inflammatory medications such as cortico- steroids and antileukotrienes to prevent or reduce the severity of attacks.

Chronic Bronchitis

Bronchitis is inflammation of the lining of the bronchial tubes. The inflammation results in the production of extra mucus, which causes the person to cough reg- ularly to clear the airways. Acute (short-term) bronchitis often occurs along with a severe cold (usually with a fever) and clears up completely on its own.

Chronic (long-term) bronchitis lasts for months but often goes unnoticed because of its gradual development. With chronic bronchitis, a mucus-producing cough lasts weeks after a cold apparently has cleared up. The coughing episodes become longer and longer after each subsequent cold. People with chronic bron- chitis begin to accept the coughing and mucus production as “normal,” espe- cially if they smoke. Usually the cough is worse in the morning and in cold, damp weather.

People with chronic bronchitis often do not seek treatment because they con- sider the cough a nuisance rather than a symptom of a medical disorder. How- ever, the chronic inflammation and accumulation of mucus provide an excellent environment for frequent infections. Lung tissue becomes permanently dam- aged, air flow is obstructed, and the reduced ability of the lungs to exchange gases forces the heart to work harder, increasing the person’s risk for cardiovas- cular disease.

Treatment for chronic bronchitis focuses on reducing irritation and inflam- mation in the bronchial tubes. If you smoke, you must quit immediately (see page 107). If you work at a job that exposes you to irritating dust or fumes, you need to use protective equipment such as masks and respirators. You should avoid exposure to people with colds or the flu, and you need to have a flu shot each year at the beginning of the flu season (usually in October).

Your doctor will prescribe antibiotics if you have an active infection in your

lungs, which may help but will not eliminate your cough. Sometimes bron- chodilator drugs are prescribed as a temporary measure to help open up the air- ways. Corticosteroid medications also may be prescribed to reduce airway inflammation. Your doctor will discuss other treatment options with you, depending on the degree to which chronic bronchitis has affected your lungs and other body systems.

Emphysema

Unlike asthma and bronchitis, emphysema affects the air sacs (alveoli) rather than the airways. Like chronic bronchitis, emphysema develops gradually and therefore occurs mainly in adults over age 45. Often the two conditions occur together. Emphysema is more common in men than in women. Except in rare cases that result from a genetic disorder, emphysema usually develops after many years of smoking.

Chemicals in tobacco smoke cause cells in the lungs to produce too much of one protease (elastase) and too little of another protease (elastase inhibitor). (Protease, elastase, and elastase inhibitor are enzymes.) This imbalance damages the elastic tissue in the walls of the alveoli and the tiny bronchioles that lead to each alveolar sac. As a result, the overall surface area of the alveoli is reduced and the alveolar walls become thickened, which limits gas exchange (the exchange of carbon dioxide for oxygen). This reduces the amount of oxygen that the lungs transfer to the bloodstream, which can lead to heart and kidney failure. As more and more alveoli and bronchioles collapse and as the lungs lose their elasticity, breathing becomes labored, causing shortness of breath, and exhaling, in particular, becomes increasingly difficult.

Because the damage to lung tissue is permanent, treatment for emphysema focuses on providing relief of symptoms and preventing progression of the dis- ease. If you smoke, you must quit immediately (see page 107). Your doctor may prescribe bronchodilators to help open your airways. Pulmonary rehabilitation, a comprehensive treatment program that strives to improve the comfort and func- tioning of a person with a chronic lung disease, can be helpful for some people. Other people may benefit by using supplemental oxygen supplied through a portable tank or a machine called a concentrator. For advanced cases of emphy- sema, lung transplantation or lung volume reduction surgery (removal of the most damaged portions of the lung) may be performed.

Lung Cancer

Changes in the structure of some of the many types of cells that make up the lungs may begin almost immediately upon exposure to carcinogens (cancer- causing substances). Some of the thousands of chemicals contained in tobacco smoke—both inhaled directly and released into the air through secondhand smoke—are known respiratory carcinogens. Substances such as radon, asbestos, arsenic, uranium, and certain petroleum products also can cause lung cancer.

Regular exposure to any of these substances can damage individual cells in the lungs, causing them to multiply into an abnormal mass of cells called a tumor. The tumor can be benign, which means that it will not spread to other parts of the body and usually will not grow back if it is removed. If the tumor is malignant, however, it can invade and destroy sur-

rounding tissue and may spread to other parts of the body through the bloodstream, causing new tumors (called metastases) to form in other tis- sues. And because all blood flows through the lungs, cancer that begins elsewhere in the body may spread to the lungs.

A tumor in one of the bronchi can irritate the lining of the airway and cause a persistent cough, which may cause the tumor to bleed. As it grows, the  tumor  may  block  the  airway, resulting in repeated bouts of pneumonia or other respiratory infections. A tumor located in the outer part of a lung may not produce any symptoms until it is large enough to press against the chest wall and cause pain. If you experience any of the warning signs of lung cancer (see box), see your doctor as soon as possible.

Tests for lung cancer include a chest X ray, a microscopic examination of mucus expelled from your lungs, and a computed tomography (CT) scan

or magnetic resonance imaging (MRI) of your chest. If something resembling a tumor is seen on an X ray or a scan, your doctor may perform a bronchoscopy (see “Diagnostic Procedures,” page 256) and a biopsy (removal of a small piece of tissue from the suspected tumor for examination under a microscope). Depending on the results, other tests and procedures may be performed to iden- tify the type of cancer and the extent to which it has spread.

Two major types of cancer begin in the lungs. Non-small cell lung cancer gen- erally grows and spreads slowly. This form of cancer accounts for about three fourths  of  all  cases  of  lung  cancer. The  non-small  cell  cancers  include squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. The less common small cell lung cancer (sometimes called oat cell cancer) grows quickly and is more likely to spread to other parts of the body, such as the lymph nodes, brain, liver, and bones.

Treatment of lung cancer depends on the type of cancer cell involved, the size and location of the primary (or first) tumor, and the size and location of any

secondary tumors (tumors that have spread from the primary tumor to another part of the body). Treatment options include surgical removal of the lung tumor, use of anticancer drugs (chemotherapy), use of radiation (radiation therapy), use of lasers (photodynamic therapy), or a combination of these treatments.

Although treatment is improving, the outlook for lung cancer is generally poor. If you smoke or are exposed to any known carcinogens, you should imme- diately take steps to prevent lung cancer.

Warning Signs of Lung Cancer
If you smoke or are regularly exposed to tobacco smoke or other airborne carcino- gens (cancer-causing substances), you are at significant risk for developing lung cancer. Contact your physician immediately if you experience any of the following symptoms:

•   persistent cough

•   chest pain

•   unexplained weight loss

•   loss of appetite

•   shortness of breath, wheezing, or hoarseness

•   coughing up blood or bloody mucus

•   persistent fever

•   recurrent respiratory infections such as pneumonia or bronchitis

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