Respiratory Diseases
Respiratory Diseases
There are many different types of respiratory diseases that interfere with the vital process of breathing. Respiratory obstructions arising from diseases can occur in the nasal area, the regions of the throat and windpipe (upper respiratory system), or in the bronchial tubes and lungs (lower respiratory system). The common cold and allergic reactions to airborne pollens block the nasal passages by creating nasal inflammation (rhinitis). Viral and bacterial infections of the upper respiratory tract inflame various parts of the airways. These infections lead to fever, irritation, coughing, and phlegm, which is mixture of mucus and pus. Inflammations may occur in the throat (pharynx), tonsils, larynx, and bronchial tubes. Damage to these parts of the respiratory system and to the lungs can also result from the inhalation of tobacco smoke, air pollution caused by smog, and industrial waste products.
With the mid-twentieth-century discovery and use of antibiotics, the two major respiratory killers of the past, tuberculosis and pneumonia, were brought under control. In place of those diseases, lung cancer began to emerge in the 1940s as an epidemic disease among those who are heavy smokers of cigarettes and those who are exposed to some forms of hazardous environmental pollution. Worksite populations exposed to such materials as asbestos, chromium, and radioactive substances were also found to have a higher incidence of lung cancer.
Colds, flu, and allergies
Colds, like flu and allergies, challenge the breathing process. There are no cures for these conditions, but they are usually not life threatening, unlike many other respiratory diseases. Prescription medicines and over-the-counter medications may provide temporary relief of the discomforts associated with colds, flu, and allergies, while asthma, tuberculosis, and other respiratory diseases require long-range medical attention and supervision.
Colds
The entire tubular system for bringing air into the lungs is coated by a moist mucous membrane that helps to clean the air and fight infection. In the case of a cold, the mucous membrane is fighting any one of over 200 viruses. If the immune system is unsuccessful in warding off such a virus, the nasal passages and other parts of the upper respiratory tract become inflamed, swollen, and congested, thus interfering with the breathing process. The body uses the reflex actions of sneezing and coughing to expel mucus, a thick sticky substance that comes from the mucous membranes and other secretions. These secretions come up from the infected areas as phlegm.
Coughing is a reflex action that helps to expel infected mucus or phlegm from the airways of the lungs by causing the diaphragm to contract spasmodically. It is characterized by loud explosive sounds that can often indicate the nature of the discomfort. While coughing is irritating and uncomfortable, losing the ability to cough can be fatal in an illness such as pneumonia, where coughing is essential to break up the mucous and other infected secretions produced by the body in its battle against the disease.
Antibiotics kill bacteria but not viruses; hence they are not effective against cold viruses. The body has to build up its own defense against them. Since there are so many different types of viruses that can cause a cold, no vaccine to protect against the cold has as yet been developed. Though the common cold by itself is not a serious condition, it poses a threat because of the complications that may arise from it, especially for children, who are much more prone to colds than older people. Colds are usually contracted in the winter months, but there are other seasonal conditions that make individuals receptive to colds.
Influenza
other viruses cause different types of influenza, such as swine flu, Asian flu, Hong Kong flu, and Victoria flu. Some of the symptoms of influenza resemble the common cold, but influenza is a more serious condition than a cold. It is a disease of the lungs and is highly contagious. Its symptoms include fever, chills, weakness, and aches. It can be especially dangerous to the elderly, children, and the chronically ill. After World War I (1914–1918), a flu epidemic killed 20 million people throughout the world. Fortunately, there has so far not been a repetition of such a severe strain of flu. Flu vaccines provide only seasonal immunity, and each year new serums have to be developed for the particular strain that appears to be current in that period of time.
Allergic rhinitis
Every season throughout the world, ragweed and pollens from grasses, plants, and trees produce the reactions of sneezing, runny nose, swollen nasal tissue, headaches, blocked sinuses, fever, and watery, irritated eyes in those who are sensitive to these substances.
These are the symptoms of hay fever, which is one of the common allergies. The term hay fever is really a misnomer because the condition is not caused by hay and does not cause fever. Allergic respiratory disturbances may also be provoked by dust particles. Usually, the allergic response is due more to the feces of the dust mite that inhabits the dust particle. The dust mite’s feces are small enough to be inhaled and to create an allergic respiratory response.
Colds and allergic rhinitis both cause the nasal passages and sinuses to become stuffed and clogged with excess mucous. In the case of a cold, a viral infection is responsible for the production of excess mucus. Inhaling steam with an aromatic oil is recommended for the cold. Decongestants are recommended to avoid infection from the excess mucous of the common cold. In seasonal allergic rhinitis, the symptoms result from an exaggerated immune response to what, in principle, is a harmless substance. Histamines released by the mast cells play a major role in an allergic immune response, and it is these chemicals, for the most part, that are responsible for the allergy symptoms.
Treatments
Antihistamines are used to block the body’s production of histamines that cause allergy symptoms. Cold medicines usually contain antihistamines, decongestants, and non-narcotic analgesics like aspirin. Though the antihistamines are not effective against the cold viruses, they do cause drowsiness, and that may help to alleviate the sleeplessness that often accompanies a cold. The analgesics help against the fever and headaches that accompany a cold, while the decongestant temporarily relieves a stuffy nose.
While decongestants can be taken orally, the two most effective ways of taking decongestants are nose drops and nasal sprays. Caution should be taken to prevent what is known as the rebound congestion effect. The decongestant medicine is applied right to the site of the swollen tissues, where it relieves the congestion in minutes by constricting the blood vessels. When decongestants are discontinued after prolonged use, the body may fail to marshal its own constrictive response. The congestion can then become worse than before the medicine was taken. Therefore, it is advisable to use decongestants for only a short period of time.
Bronchial diseases
Asthma, chronic bronchitis, and emphysema are complex illnesses for which there is no simple treatment. Treatments depend on the severity of the conditions. All three conditions are characterized by an involuntary smooth muscle constriction in the walls of the bronchial tubes. When nerve signals from the autonomic nervous system contract the bronchial muscles, the openings of the tubes close to the extent of creating a serious impediment to the patient’s breathing.
Acute bronchitis is a short-term illness that occurs as a result of a viral infection of the bronchi. It is treated with antibiotics and may require attention in a hospital. Chronic bronchitis is a long-term illness that can be caused by such environmental factors as air pollution, tobacco smoke, and other irritants. There is a persistent cough and congestion of the airways.
In emphysema, the air spaces spread out beyond the bronchial tubes. Both chronic bronchitis and emphysema restrict air flow and there is a wheezing sound to the breathing. Unlike asthma, however, these two illnesses are not easily reversible. Airway constriction in the case of bronchitis and emphysema is less severe than in the case of an asthma attack, however.
Asthma is a disorder of the autonomic nervous system. While the cause for the condition is unknown, there is a connection between allergies and asthma in that an allergic reaction can trigger an asthma attack. Nerve messages cause muscle spasms in the lungs that either narrow or close the airway passages. These airways consist of narrow tube-like structures that branch off from the main bronchi and are called bronchioles. It is the extreme contraction of the muscle walls of the bronchioles that is responsible for the asthma attack. These attacks come and go in irregular patterns, and they vary in degree of severity.
Bronchodilators
Bronchodilators are used in the treatment of asthma, chronic bronchitis, and emphysema. A bronchodilator is a medicine used to relax the muscles of the bronchial tubes. It is usually administered as a mist through an inhaler. Some are given orally as a tablet. Administered with an inhaler, they go straight to the lungs for fast action. Since they do not enter the bloodstream, they have few side effects.
Anticholinergic bronchodilators are also taken by inhalation. They take more time to work than the sympathomimetic medicines, but they remain effective for a longer period of time. Their job is more prevention than immediate relief. They work by countering signals from the parasympathetic nervous system to constrict the bronchioles. These signals send their messages to the cholinergic receptors on the muscle wall of the bronchioles. The anticholinergic medicine blocks the receptor. Atropine is an example of an anticholinergic bronchodilator.
Xanthines date back to the ancient world. They have been used as medicines for a number of conditions. Caffeine is a type of xanthine. Theophylline is the active ingredient of the xanthines. They relax smooth muscle and stimulate the heart. They are particularly effective in relaxing the muscle walls of the bronchioles. Taken orally, they act directly on the muscle tissue. It is not certain how the xanthines work, but they seem to prevent mast cells from releasing histamines while inhibiting other enzymatic actions.
Tuberculosis
Tuberculosis is an infectious disease of the lungs caused by bacteria called Mycobacterium tuberculosis. It was one of the major causes of death until the introduction of antibiotics in the 1940s. The bacillus is transmitted by the coughing of an individual who has an advanced case of the disease and infects the lungs of uninfected people who inhale the infected droplets. The disease is also spread through unpasteurized milk, since animals can be infected with the bacteria. The disease is dormant in different parts of the body until it becomes active and attacks the lungs, leading to a chronic infection with such symptoms as fatigue, loss of weight, night fevers and chills, and persistent coughing that brings up sputum-streaked blood. The virulent form of the infection can then spread to other parts of the body. Without treatment the condition is usually fatal.
In the past, well-to-do tubercular patients were often sent to rest homes called sanitoriums, preferably located in a mountain area or desert retreat, so they could enjoy the benefits of clean air. Today, tuberculosis is treated with antituberculous drugs, such as streptomycin, which are taken over a long period of time.
Populations most at risk of contracting TB are people who have certain types of medical conditions or use drugs for medical conditions that weaken the immune system; people in low-income groups; people from poorer countries with high TB rates; people who work in or are residents of long-term care facilities (nursing homes, prisons, hospitals); and people who are very underweight, as well as alcoholics and intravenous drug users.
During the 1990s, the prevalence of TB began to increase in the United States. Those who are poor and homeless are particularly at risk of acquiring TB, as their harsh life and often poor nutrition can impair the fuctioning of their immune system.
Pneumonia
Pneumonia, another life threatening disease, is an infection or inflammation of the lungs caused by bacteria, viruses, mycoplasma (microorganisms that show similarities to both viruses and bacteria), and fungi, as well as such inorganic agents as inhaled dusts or gases. The irritation to the lung tissues from these sources destroys the alveoli (air sacs) of the lung. Blood cells from lung capillaries then fill the alveolar spaces. The affected part of the lung loses its elasticity and can no longer fulfill its vital tasks of supplying the rest of the body with oxygen and eliminating carbon dioxide gas. Symptoms of this disease include pleurisy (chest pain), high fever, chills, severe coughing that brings up small amounts of mucus, sweating, blood in the sputum (pus and mucus), and labored breathing.
Pneumonia infections are divided into two classes: in lobar pneumonia one lobe of the lung is affected, whereas bronchial pneumonia shows up as patches of infection that spread to both lungs. Pneumococcus bacteria are responsible for most bacterial pneumonia. The lobes of the lung become filled with fluid, and the bacterial infection spreads to other parts of the body. There is a vaccine for this type of pneumonia. Viruses cause about half of all the pneumonias. Influenza viruses may invade the lungs, which in this case, do not become filled with fluid. The symptoms of viral pneumonia, which are not as serious as those of bacterial pneumonia and last for shorter periods of time, are similar to those of influenza.
Mycoplasma pneumonia is not as severe as bacterial pneumonia, either. Even if untreated, this type of pneumonia is associated with a low death rate. A more recent type of pneumonia that made its appearance with the AIDS (acquired immune deficiency syndrome) epidemic is pneumocystis carinii pneumonia (PCP). It is caused by a fungus and is often the first sign of illness a person with AIDS experiences. Other less common pneumonias are beginning to appear more frequently and require preventive measures (if possible, early detection and effective treatment). In 1936 pneumonia was the main cause of death in the United States. Since then it has been controlled by antibiotics, but as resistant strains of bacteria have developed, the number of cases has increased. In 1979 pneumonia and influenza combined formed the sixth major cause of death in the United States.
Cancer
As a respiratory disease, lung cancer has now become the leading cause of death from cancer in men. It accounts for the second largest number of cancer deaths in women. Cigarette smoking and air pollution
KEY TERMS
Antibiotics— Drugs that target and kill bacteria, but are ineffective against viruses.
Bonchodilators— Drugs used to dilate the bronchioles.
Bronchiole— The smallest diameter air tubes, branching off of the bronchi, and ending in the alveoli (air sacs).
Carcinoma of the lung— The most common form of lung cancer.
Histamine— A chemical released from cells in the immune system as part of an allergic reaction.
Pneumoconioses— The class of respiratory diseases caused by the inhalation of inorganic chemicals.
Pneumocystis carinii pneumonia— A type of pneumonia occurring in AIDS, which is caused by fungi.
Pulmonary fibrosis— Scarring of the lung tissue from disease or drugs.
Rhinitis— The common condition of upper respiratory tract inflammation occurring in both colds and allergy.
TB skin test— The use of tuberculin, a protein produced by the tuberculosis bacillus, to test for TB.
are considered to be the two main causes of lung cancer. The three types of lung cancer are carcinomas, lymphomas, and sarcomas. The survival rate after five years for carcinomas, which can originate in the trachea, bronchi, or alveoli, is low. Lymphomas originate in the lymph nodes, while sarcomas develop either in the lungs or in other body tissues. Treatment includes the use of chemo-therapy, radiation, and surgery, that is, the removal of the affected parts of the lung.
Miscellaneous disorders
Noncancerous (benign) tumors may occur throughout the respiratory system. Although benign tumors are less serious than malignant ones, they can still cause serious obstructions of the airways and other complications. They may later become malignant.
Different types of drugs like heroin can cause edema (lung fluid). Anticancer drugs can cause pulmonary fibrosis (scar tissue), which will interfere with breathing. There are also children’s diseases like cystic fibrosis, which affects secretion by the glands and results in pulmonary disorders along with other complications. Whooping cough (pertussis), which may lead to pneumonia and respiratory distress syndrome in newborns, especially premature ones, is another example of a children’s disease.
Structural disorders may occur after changes in the shape of respiratory organs take place, following diseases such as pneumonia or tuberculosis or from hereditary causes. There are also a number of diseases caused by the inhalation of dust products from coal mining (black lung disease), sandblasting (silicosis), and manufacturing (asbestosis and berylliosis). These diseases are classified as pneumoconioses. The respiratory tract can also be affected by many diseases in other organs or systems of the body such as the heart, kidneys, and immune system.
Resources
BOOKS
Appel, Melanie. Cystic Fibrosis: It Happened To me. Lanham, MD: Scarecrow Press, 2006.
Hedrick, Hanna L. The Quiet Killer: Emphysema/Chronic Obstructive Pulmonary Disease. Lanham, MD: Scarecrow Press, 2002.
Kepron, Wayne. Cystic Fibrosis: Surviving Childhood, Achieving Adulthood. Tonawanda, NY: Firefly Books, 2004.
Reichman, L.B., and J.H. Tanne. Time Bomb: The Global Epidemic of Multi-Drug Resistant Tuberculosis. New York: McGraw-Hill, 2001.
Wilkins, Robert L., James R. Dexter, and Philip M. Gold. Respiratory Disease: A Case Study Approach to Patient Care. Philadelphia: F.A. Davis Company, 2006.