Disorders That Obstruct Air Flow
The flow of air from the lungs can be limited or obstructed by a variety of structural changes in the lungs. Chronic obstructive pulmonary disease (COPD), a major cause of disability and death in men, refers to asthma, chronic bronchitis, and emphysema. With COPD the airway obstruction is generally irreversible. With asthma the obstruction is reversible with treatment, although the disease itself may not be cured.
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 constricted (narrowed), very little air passes through to the alveoli, and oxygen levels 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.
Controlling environmental factors that can trigger an asthma attack (see post Triggers of Asthma Attacks) 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 timing of administration. Avoid relying exclusively on short-term rescue medications 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 corticosteroids and antileukotrienes to prevent or reduce the severity of attacks.
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 regularly 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 bronchitis begin to accept the coughing and mucus production as “normal,” especially 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 consider the cough a nuisance rather than a symptom of a medical disorder. However, the chronic inflammation and accumulation of mucus provide an excellent environment for frequent infections. Lung tissue becomes permanently damaged, 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 cardiovascular disease.
Treatment for chronic bronchitis focuses on reducing irritation and inflammation in the bronchial tubes. If you smoke, you must quit immediately. 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 bronchodilator drugs are prescribed as a temporary measure to help open up the airways. 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.
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 disease. If you smoke, you must quit immediately. Your doctor may prescribe bronchodilators to help open your airways. Pulmonary rehabilitation, a comprehensive treatment program that strives to improve the comfort and functioning 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 emphysema, lung transplantation or lung volume reduction surgery (removal of the most damaged portions of the lung) may be performed.