___________________________________________________________ Asthma: Diagnosis and Management
Isocyanate One of the most powerful asthmagens is isocyanate. “Instant foam” kits sold for do-it-yourself insulation can provoke asthma in those who were previously not asthmatic. This is due to two different substances that are mixed to create the polyurethane foam, one of which is unreacted isocyanate. The combination of these substances results in the release of isocyanate at poten- tially harmful levels[ [8; 48]. The most common incidences of isocyanate asthma occur in patients who have high exposures in their occupation. The National Institute for Occupational Safety and Health has published an alert regarding the risks to U.S. workers exposed to diisocyanate [54]. Although IgE antibodies against isocyanate may be detected by a RAST, this test is positive in only a minority of cases of isocyanate asthma. Occupational Asthmagens Any job may present a worker with some environmental hazards. For a patient with asthma, this risk is heightened as a result of the many harmful agents that may be released into the environment and inhaled into the lungs. Some of the most potent irritants are hard metal dusts, such as silica, asbestos, and talc, used in mining and refineries. Fumes from fluorocarbon propellants and oxide of such metals as copper, zinc, manganese, and iron are also on a long list of agents that provoke lung diseases and disorders, including asthma. Other work-related agents that can cause asthma include animal proteins, enzymes, wheat flour, and certain reactive chemicals [8; 55]. Since the healthcare industry has required personnel to wear protective gloves, more healthcare professionals have discov- ered that latex allergies trigger airway sensitivity. Healthcare providers who have known sensitivities should also be aware of contact with irritants such as disinfectants, formaldehyde, sulfathiazole, chloramine, and psyllium [8; 55]. Office workers in insulated office buildings with central air conditioning systems may never find the source of their symptoms; fewer than 40% of those who feel sick on the job ever discover exactly which pollutant to avoid. Common office triggers include paper dust, perfumes or colognes, industrial cleaners, and mold. Additional and ongoing research contin- ues to provide information about irritants and occupational asthma [8; 55]. Viruses Many consider upper respiratory tract infection or rhinoviruses to be the most important (and for many patients, the most significant) asthma trigger other than allergy. Viral infections such as these, also referred to as “the common cold,” are known to cause complications for many (30% to 40%) patients with asthma. For those without asthma, these infections are usually single nuisances characterized by spontaneously resolving symptoms typically lasting about 7 to 10 days. Symptoms include nasal congestion and drip, postnasal drainage, sore throat, edematous glands, and at times, fatigue. In some instances, the lower respiratory tract may also be involved, and individuals without asthma can develop bronchitis with cough; these symptoms can be confused with allergic reactions
in atopic patients. There are more than 200 viruses capable of causing what is generally recognized as a cold. It may be worth noting that colds, especially versions produced by RSV, are often the event that precipitates the onset of asthma in children and adults. In fact, these infections not only often precipitate acute events, but they seem to alter the immune system response to initiate the development of allergy or asthma [8; 47; 56]. Asthma episodes that are the result of viruses may be severe and sudden in onset; lower respiratory tract symptoms of cough- ing, wheezing, and shortness of breath can occur within 24 hours after the onset of upper respiratory tract viral symptoms, such as nasal congestion. Occasionally, wheezing may occur without any premonitory upper respiratory tract warning, so the patient with asthma should be alert to the earliest onset of chest symptoms as well as the premonitory upper respira- tory tract symptoms that usually precede them. It is known that early treatment, especially with oral corticosteroids, may prevent the often serious asthmatic consequences of a viral infection. It is imperative, therefore, that patients are able to recognize early warning signals. Vaccination for typical respira- tory viruses, such as influenza, measles, varicella (chicken pox), and pertussis, should be considered as a preventive measure, especially in children. The CDC Advisory Committee on Immunization Practices and GINA recommend that people with asthma receive either the Moderna or Pfizer-BioNTech COVID-19 vaccine series [8; 57]. Weather Some patients with asthma will indicate that they are able to predict weather because they notice their symptoms worsen or disappear with fluctuating barometric pressures and sudden, extreme temperature shifts. Symptoms such as chest tighten- ing and excess mucus production may warn of high humidity, thunderstorms, snowstorms, or freezing temperatures [8; 47; 48]. Cold air, which usually does not limit airflow with other lung diseases, is a major trigger for many individuals with asthma. Bronchial muscles constrict in cool, dry air, and muscles may not relax until temperatures rise. Even ingesting cold foods or drinks can cause muscle constriction. Exercise during cold weather increases the risk of bronchial constriction by forcing inhalation of cold air [8; 47; 48]. Diet An anti-asthma diet is generally neither an avoidance diet nor a diagnostic diet, but rather a health-promoting diet, designed to protect against asthma and asthma symptoms. However, if specific food allergies or triggers are identified, they should be avoided as much as possible. Patients with asthma with food sen- sitivities and/or those who care for them should be made aware of potentially allergenic-specific food ingredients (Append ix). Because overweight and obesity have been linked to an increased risk for asthma, some patients may benefit from weight loss and limiting their calorie intake to lose weight.
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