See Bronchodilator.

An emergency is an unforeseen condition, or set of circumstances, that requires prompt action. A true medical emergency is usually one in which the patient’s life is threatened and the patient needs im­mediate medical" attention. This definition implies that the medical condition is of very recent onset or that it is perhaps part of a chronic illness that has suddenly become more severe. Because it is sometimes difficult for either the patient or the physician to know whether the illness is immediately life-threatening, any similar con­dition that resulted in death should be considered life-threatening. This chapter deals mainly with such emergencies, as well as with serious but nonfatal, acute conditions. Allergic emergencies are those associated with the classic allergy diseases asthma, hay fever, hives, and eczema, as well as allergic reactions to foreign matter, whether the matter is ingested, injected, inhaled, or absorbed by the skin. Although allergic diseases usually involve an immunological mechanism, some conditions closely re­semble an allergic condition in which immunological causes may not have been demonstrated. These will also be discussed when appro­priate.

Foreign substances are those that are not a natural, integral part of the body, that cause allergic reactions resulting in emergencies, or that produce fairly severe reactions. They are generally not danger­ous —that is, they are not poisons, pathogenic organisms (such as viruses or bacteria), or radiation. These foreign, generally innocuous, substances are called, collectively, allergens. They may be inhaled, ingested, injected, or absorbed by the skin. They usually contain proteins that are medium-sized in molecular weight. Almost in- variably, prior contact with either the identical agent or a closely related agent must occur before the allergic reaction is triggered. Allergens that cause allergic reactions may be classified accord­ing to their sources, and are found in Table 3.1. Some of the drugs listed—for example, aspirin and the dyes used in x-ray studies—are not, strictly speaking, allergens, since a true immunological mecha­nism has not been found. The drugs are included both for traditional reasons and because they so closely reproduce reactions to true allergens.

Rejection is the destruction of transplanted foreign tissues or cells by hypersensitivity reactions of the recipient; also called a graft rejection. There are several types of graft, depending on the species involved, and several patterns of graft rejection.

A reaction of any sort after an allergy shot probably means that the dosage is too high and that it should be reduced. Seek the advice of the allergist who is providing you with the injections.

The actual cause, or causes, of asthma is not known. To develop asthma, it is probably necessary for a person to be predisposed ge­netically, and to be exposed to such environmental factors as infec­tions or to allergens such as house dust and mold. Some people develop a condition similar to asthma after a viral infection. When the infection clears, the patient’s airways continue to be irritated. Thus one important difference between an asthmatic and a person in normal health is the persistence of bronchial obstruction after an infection. The viral theory, then, is one possible explanation for the development of asthma. From a practical point of view, al­though the physician does not necessarily know the cause of the asthma, he or she can prescribe treatment that takes into account many of the causative factors. The human body must constantly try to overcome those forces that would lead to continuous bronchial obstruction. Its success is obvious, since the asthmatic does not wheeze or experience tightness all of the time. Asthma is characterized by periods of ups and downs. It is also true that relatively mild bronchial obstruction which may not be apparent to the patient will show up in breathing tests in a doctor’s office. If many stimuli are responsible for a given amount of broncho-constriction in a patient, the elimination of one or more stimuli might result in sufficient improvement for the patient to be aware of the improvement. A patient may mistakenly perceive a cause-and-effect relationship between an environmental stimulus and the bronchial obstruction that seems to result from it. Many stimuli are more important in caus­ing an attack when the patient is about to wheeze than when the patient is relatively symptom-free. Misunderstanding of this relation­ship has led to some current myths about asthma. One example, is the woman who develops asthma at the time of her husband’s death. She forgets how run-down she was and about the infection she acquired earlier. Her asthma might inappropriately be called psychogenic. An­other example is the man. who develops asthma during the Christmas season and who is convinced that the Christmas tree was the cause. He overlooks the upper respiratory infection and other problems that occurred simultaneously. Still another example is the man who ascribes his asthma to his mother-in-law. He develops symptoms in her house but overlooks the possibility that her cat is responsible. The physician familiar with the body mechanisms that provoke wheezing is in the best position to help the patient understand these mechanisms. The patient should also keep in mind that asthma itself is not a simple illness, that approaches used by different physicians may vary. The interested reader should note the following points. 1. Patients differ with respect to the causes of attacks. In some cases, infections seem to play a major role; in others, stimulants such as strong odors, exercise, laughing, or cold air are important. In still other patients, a truly allergic reaction may be the most im­portant factor. 2. Patients differ with respect to the location of the major areas of obstruction. Some seem to have obstruction primarily in their large breathing tubes, whereas others have it mainly in their small breathing tubes; others have obstruction in both. The collapsibility of bronchial tubes also varies, and this can affect breathing tests. Some patients trap too much air and thus overexpand their lungs. 3. Patients differ in how much the obstruction in their airways can be reversed. The concept of reversibility has already been mentioned. The most common test of reversibility is the patient’s reaction to an aerosolized bronchodilator such as Isuprel Misto-meter or Bronkosol. Some people require prolonged, around-the-clock therapy, which often includes daily or every-other-day ster­oid therapy before normal breathing is regained. Despite much medication, many improve their bronchial airway obstruction but never return to a normal state. Patients with obstructive airways disease who show no evidence of reversibility even after the most rigorous therapy program known may suffer from a serious con­dition such as emphysema. These patients, however, do not have asthma. 4. People differ in their response to various medications. Some are "responders" to many of the medications used in the treatment of asthma, and some are "nonresponders." 5. People also differ as to the amount of medication necessary to produce the desired effect. It may take eight times longer for one person to eliminate theophylline (the most common antiasthmatic medication) from the body than it does for another. Thus the dose necessary for controlling asthma symptoms may vary significantly from one person to another. Indications of Asthma A patient who is examined between attacks may appear normal. Usually, though, wheezing caused by forced expiration is detectable in the chest. During a severe attack, the patient may use both belly and neck muscles to breathe. The chest may expand, the person may turn blue and lose fluid through sweating, and the heart may begin to beat rapidly (although this is sometimes caused by the medication used to treat asthma attacks). The absence of wheezing during a se­vere attack could actually be a bad sign, indicating that the bronchial tubes have filled with mucus. In the next few pages we discuss some factors that contribute to the onset of asthma. Hereditary Although genetic factors are important, they should not be over­emphasized. The absence of a family history of allergy does not mean that someone cannot have an allergy. By the same token, a family history of allergy does not mean that the patient cannot have a non-allergic cause for his asthma. People inherit at least two important components that do not necessarily come from the same genes: the immunologic responses involving antibodies responsible for an aller­gic reaction, and organ hyperreactivity, or "twitchy lung." Inheritance becomes even more complicated when other possible genetic factors are considered, such as the number and location of the cells that re­lease asthma-triggering substances. Even the blood supply to these cells is suspect. Immunologic The immune system of the human body is extremely complex. Four types of immune reactions have been studied and described, two of which may be responsible for some common allergic problems. When a foreign substance enters the body, the body’s response is to manu­facture a defensive substance called an antibody. The antibody has a shape similar to that of the foreign substance; this enables the anti­body to attach itself to the substance, much as two pieces of a jigsaw puzzle fit together, and deactivate it. Some antibodies are protective, while others contribute to adverse reactions such as sneezing and wheezing. The antibody known as immunoglobulin E is associated with most immediate allergic reactions, for example, those associated with hay fever and asthma. A Type I reaction occurs when an allergic foreign substance combines with immunoglobulin E. Wheezing may also accompany the interaction between a foreign substance such as mold and immunoglobulin G (which is usually protective). This type of antibody causes a Type III reaction. Immunologic processes that work through certain blood cells of the body, causing a Type IV reaction, may contribute to the reactions mentioned above; but just how this type of interaction works has not yet been determined. As knowledge of these immunologic reactions increases, physicians will be better able to characterize allergic diseases and treat them. Physiological ^^* Tests of breathing are called pulmonary function tests. They mea­sure the capacity of the lungs to stretch, the volume of air that flows through them, the extent of obstruction to airflow, and the distribu­tion of air in the chest. Tests can be administered that compare the supply of blood with the supply of air in
the lungs, and measure a patient’s response to various medications so that the patient can be given the most effective medication. In attempting to diagnose reversible lung disease, several types of bronchodilators, and even corticosteroids, may have to be tried. If the patient still does not respond, a diagnosis of irreversible lung dis­ease is reached. Psychological Over a period of a few years, some hospitalized asthmatic patients were asked to fill out a questionnaire listing the symptoms they expe­rienced during an asthma attack. Seventy-seven symptoms were recorded and divided into five symptom categories. Patients experi­encing much panic and fear during an asthma attack needed to be on high doses of the most potent medications. They also requested more medication from their doctors even though their pulmonary function tests revealed little change. This high panic-fever response may ac­tually contribute to patients’ personal view of themselves as invalids, and therefore as being more vulnerable to an asthma attack. Such pa­tients may also overmedicate, thus becoming more susceptible to side effects that could otherwise be avoided. On the other hand, patients with a low panic-fear response requested medication infrequently even when they needed treatment. Like other groups of patients with chronic illnesses, asthmatic pa­tients develop various ways of coping with their asthma. When they believe they must yield to the disease, they often do so, with the result that they make their condition worse. This is often true of children who find that they get more attention from their parents and families when they are ill. Some patients respond to suggestion; others do not. A suggestible patient might experience tightness in the chest just at the thought of contact with a cat or a dog. Even an artificial rose can induce tight­ness if the stimulus is a reminder of a previous bronchoconstriction. By identifying this group of asthma patients, physicians can prescribe treatment programs that minimize the power of suggestion during an asthma attack. Biochemical Biochemical factors are difficult to understand, and new theories are constantly being proposed. The body contains specialized cells that have attachment sites on their surface with which chemicals inter­act. These sites, called receptors, are divided into three main groups: alpha adrenergic, beta adrenergic, and cholinergic. The interaction of these receptors corresponds to changes in cyclic adenosine mono­phosphate (cyclic AMP). Formation of cyclic AMP causes a favor­able response, since the formation is related to bronchodilation and prevention of the release of chemicals within the cells involved in bronchoconstriction. Another substance—cyclic guanosine mono­phosphate (cyclic GMP)—is thought to have the opposite effect: contributing to bronchoconstriction. The influence of the cholinergic receptor is exerted through cyclic GMP. Researchers and physicians believe that cigarette smoke, automobile fumes, and strong odors con­tribute to the interaction of these substances. The medications commonly used in treating asthma are thought to work through cyclic AMP and cyclic GMP biochemical pathways. Epinephrine, isoproterenol, metaproterenol, and terbutaline stimulate cyclic AMP formation and cause bronchodilation. Theophylline in­hibits cyclic AMP breakdown, producing the same net effect. Pheno-tolamine sometimes causes bronchodilation by increasing cyclic AMP. Through another mechanism, such substances as atropine block cyclic GMP levels and produce bronchodilation. Corticosteroids seem to affect beta adrenergic receptors as one of their modes of action. A recent theory of asthma suggests that an antibody is directed against the beta adrenergic receptor. Hormonal Although hormonal factors are probably important, data explain­ing their exact role are insufficient. Among some women, asthmatic symptoms have been found to worsen during menstrual periods or during pregnancy. Other patients may develop a severe worsening of their asthma, along with a hyperactive thyroid; improvement is possible only after the thyroid condition is treated. Clinical Although, historically, the most common complaint of the asth­matic patient is tightness in the chest, other common symptoms of asthma are cough, wheezing, and shortness of breath, followed by symptom-free periods’. Among some people, a persistent chronic cough, especially at night, or shortness of breath, with a heavy pro­duction of sputum, are the main symptoms. Wheezing is a sound made by a rapid flow of air through the airways. As is true of a musical instrument, sound is produced only when the airflow is sufficient. The lungs of some patients may be too tight for them to wheeze; in these people, mucus plugs block the flow of air through the bronchial tubes. An asthmatic usually has hyperinflated lungs, which means air is trapped and cannot be expelled during normal expiration. When the lung is in this expanded condition, the patient must work harder to breathe and thus tires more easily. Diagnosis of Asthma A diagnosis of asthma is indicated when a patient has a history of wheezing after exposure to specific environmental substances or respiratory infections and is suffering from generalized obstruction of the air passages. Although many physicians place great emphasis on family his­tories, these histories are not invariably important. Lack of history neither proves nor disproves that the patient has asthma. On the other hand, a previous history of eczema, hay fever, nasal polyps, or sinus­itis should alert the physician to the possibility of asthma. Chest X-Rays and EKGs A chest x-ray may appear either normal or overinflated, with the diaphragm pushed down. An electrocardiogram (EKG) is usually normal. During a severe attack, right-sided heart strain or enlargement may occur. Skin Tests Skin tests are used to distinguish a group of asthmatics who have allergies. Such tests alone, however, do not make possible a diagnosis of asthma. Bionchial Inhalation Challenge Bronchial inhalation challenges with antigens might also help de­fine an immunoglobulin-mediated cause for the asthma. A positive bronchial inhalation challenge to methacholine (a substance similar to acetylcholine) or histamine may help confirm a -diagnosis that is unclear, such as might result in a patient with only a chronic cough.

{not egg-free)

In medium-size saucepan, melt shortening over low heat; in it, saute green pepper and onion for about 5 minutes. Stir in rice flour; cook, stirring, for about 1 minute. Add water and cook, stirring constantly until mixture thickens. Stir in salt, lemon juice, and tuna. Add egg yolks and blend well. In a large bowl, beat egg whites until stiff but not dry. Care­fully fold in tuna mixture, then pour into ungreased 1 1/2 -quart casserole

See Hypersensitivity Pneumonitis.

Contact dermatitis is a type of reaction in which local areas of the skin become inflamed upon contact with certain substances. The area of skin itches, turns red, and may break out in papules, or blisters. In time, the lesions thicken and crack, and the skin changes color. Usually, a well-defined border develops between the affected area and the normal skin. The causative agent may act as an irritant or as a sensitizer, inducing delayed allergic reactions. Delayed contact allergy is not mediated by allergic antibodies, as it is in hay fever; instead, the allergy is produced by certain sensitized cells (lymphocytes) in response to an antigen, the substance that causes the irritation. The antigens responsible for contact allergy are usually small (in terms of molecular weight) chemicals that must first combine with local proteins before becoming antigens. Poison ivy, metals, cosmetics, and drags are common causative agents. Poison ivy belongs to the plant family Anacardiaseae and is the most common cause of contact allergy. The material that causes the reaction is an oil resin called urushiol, found in the sap of the plant. Skin reactions vary in severity from mild lesions to severe lesions that require treatment using steroids (cortisone). In highly sensitive persons who have come in contact with poison ivy, immuno­therapy has been tried; but the treatment has not yet been demon­strated as effective. Other members of the poison ivy family are eastern poison oak, western poison oak, and poison sumac. Among metals, nickel, mercury, and chromates are common sen­sitizers. Most commercial metals are contaminated by other metals, particularly nickel. For example, it is common for someone sensitive to nickel who comes in contact with a chrome-plated object to ‘have a skin reaction. The incidence of contact allergy to cosmetics is low. Probably the most common allergic reaction to cosmetics is to the chemical para-phenylenediamine, a basic ingredient in oxidation-type permanent hair dyes. Sun-screening lotions, perfumes, and lipsticks are among the cosmetics frequently associated with contact allergy. Among drags, by far the most common skin sensitizer is the anti­biotic neomycin, which is used as an antibiotic cream. Penicillin and antihistaminic creams are also frequent causes of contact allergy. Ethylenediamine, a chemical often used as a stabilizer in many topi­cal drags, is a potent sensitizer and is the cause of numerous reactions to topically administered medications.