Research Findings for Asthma - Case Study Example

Research findings for asthma Introduction Asthma is a chronic inflammatory immunological disease affecting the lungs and causes difficulty in breathing. It is a form of hypersensitivity in which the bronchioles in the lungs are narrowed by inflammation and spasm of the lining of the airway wall. During normal breathing, air is taken in through the nose and mouth and goes down the windpipe, through the airways, and into the air sacs. When we exhale, air is expelled from the lungs in the reverse order. During an asthma attack, the muscles around the airways tighten, making the opening in the airways smaller. The lining of the airways swells from inflammation, which causes an increase in mucus that blocks the airways. Because its more difficult to breathe out than to breathe in, more air is retained in the air sacs in the lungs with each breath. Someone having an asthma attack may feel as though he or she is breathing through a narrow straw or, in the case of a severe attack, may even have the feeling of near suffocation. The changes that take place in the lungs of asthmatic persons make the airways hyper-reactive to many different types of stimuli that dont affect healthy lungs. In an asthma attack, the muscle tissue in the walls of bronchi goes into spasm, and the cells lining the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi to become narrowed (broncho-constriction). As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it. Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscle to contract and stimulate mucus formation. These substances, which include histamine and a group of chemicals called leukotrines, also bring white blood cells into the area, which is a key part of the inflammatory response. Many patients with asthma are prone to react to such "foreign" substances as pollen, house dust mites, or animal dander, these are also called allergens. Signs & Symptoms An asthma attack is characterized by difficulty in breathing, periodic attacks of wheezing, shortness of breath, and a tight feeling in the chest. A cough producing sticky mucus is symptomatic. The symptoms often appear to be caused by the bodys reaction to a trigger such as an allergen (commonly pollen, house dust, and animal dander), certain drugs, an irritant (such as cigarette smoke or workplace chemicals), exercise, or emotional stress. These triggers can cause the asthmatics lungs to release chemicals that create inflammation of the bronchial lining, constriction, and bronchial spasms. If the effect on the bronchi becomes severe enough to impede exhalation, carbon dioxide can build up in the lungs and lead to unconsciousness and death (Health-cares.net, 2005). Asthma attacks may occur at anytime, but there are risk factors that can trigger an attack. Medically, asthma is a name assigned to a group of symptoms that typically include shortness of breath, wheezing, coughing, and chest tightness. Symptoms can occur in various combinations (one, several, or all) and may range from mild to severe. Symptoms are usually intermittent, perhaps happening only on rare occasions but may occur seasonally or monthly, weekly, or even daily. In the most severe cases, symptoms are present continuously. Asthmatic symptoms are usually quite variable; someone with asthma may go for periods of time without symptoms, and then suddenly have severe episodes for days at a time. The most common symptom recognized by both physicians and patients is wheezing. Wheezing is a whistling or rumbling sound that comes from the chest expiration. It may be very loud or barely audible. With mild asthma, symptoms occur no more than twice a week (with nighttime attacks no more than twice a month). The attacks don’t last long, and they are alleviated quickly with medication. There are no symptoms between attacks. With moderate asthma, symptoms occur almost every day and require an inhaler almost every time an attack occurs for symptom relief. With severe asthma, symptoms are present most of the day every day. They restrict activity, and they have often necessitated a hospital stay. Asthma usually begins in childhood or adolescence, but it also may first appear during adult years. While the symptoms may be similar, certain important aspects of asthma are different in children and adults. Children born to families with a history of allergies or asthma are more likely to have asthma. Children who live in urban areas, where there is a higher incidence of air pollution, or live in a home that has high levels of dust mites or cigarette smoke, are also at a higher risk for asthma. Infants born prematurely or who suffer lung damage shortly after birth are also more likely to have asthma (Health-cares.net, 2005). Types of Asthma Asthma is sometimes classified in various ways. Types of asthma include child-onset asthma, adult-onset asthma, exercise-induced asthma, cough-variant asthma, occupational asthma, nocturnal asthma. Asthma can actually start at any age and in a wide variety of situations. Asthma in childhood is often due to genetic reasons. When these children are exposed to house-dust mites, animal proteins, fungi, or other potential allergens, they produce a type of antibody that is intended to engulf and destroy the foreign materials. This has the effect of making the airway cells sensitive to particular materials. Further exposure can lead rapidly to an asthmatic response. Adult-onset asthma develops after age 20. It is less common than asthma in children, and studies point out that it affects more women than men. Between 30 percent and 50 percent of all adult cases are associated with allergies, but often allergic exposures dont seem to be the most important, driving factors. This nonallergic adult-onset asthma is sometimes called "intrinsic." Many adults who are not allergic do have such conditions as sinusitis or nasal polyps, or they may be sensitive to aspirin and related drugs. Another major source of adult asthma is exposure at work to animal products, certain forms of plastic, wood dust, or metals. Shortness of breath and/or wheezing occurring after strenuous exercise is called exercise-induced asthma. Although this phenomenon happens in up to 80% of people with recognized asthma, it frequently takes place as an isolated event without any other symptoms of asthma at any other time. Exercise-induced asthma involves symptoms that occur about 5-20 minutes after beginning an exercise that involves breathing through the mouth. Sports and games that require continuous activity or that are played in cold weather (for example, long-distance running, hockey, soccer, and cross-country skiing) are the most likely to trigger an asthma attack. Other physical exertions that can trigger an attack include laughing, crying, and hyperventilating. Cough variant asthma causes great difficulty for the physician to accurately diagnose the true underlying cause of the cough as being asthma because it can be easily confused with other conditions, such as chronic bronchitis and post nasal drip due to hay fever or sinus disease. Coughing can occur during day or night. Nighttime coughing is most disruptive, interfering with sleep. Occupational asthma occurs in response to a trigger in the workplace. Triggers include contaminants in the air, such as smoke, chemicals, vapors (gases), fumes, dust, or other particles; respiratory infections, such as colds and flu (viruses); allergens in the air, such as molds, animal dander, and pollen; extremes of temperature or humidity; and emotional excitement or stress. In occupational asthma, the trigger is a substance or condition in the workplace that causes asthma symptoms. Most of these substances and conditions are very common and are not normally considered hazardous. Although these substances and conditions can be encountered in almost any workplace, occupational asthma is most common in workers in the following industries and jobs. In most people with occupational asthma, the symptoms appear a short time after beginning work and subside after leaving work. Nocturnal asthma occurs between midnight and 8 am. It is triggered by allergens in the home such as dust and pet dander or is caused by sinus conditions. Nocturnal or nighttime asthma may occur without any daytime symptoms recognized by the patient. This is called "nocturnal asthma." The patient may have wheezing or short breath when lying down or may not notice these symptoms until awoken by them in the middle of the night, usually between 2 and 4am. Nocturnal asthma may occur only once in a while or frequently during the week. Nighttime symptoms may also be a common problem in people who have daytime asthma as well, but then its true nature is more readily recognized. The cause (or causes) of this phenomenon is unknown, although many possibilities are under investigation. While the majority of patients respond to regular inhaled glucocorticoid (steroid) therapy, some are steroid resistant. Airway inflammation and immune activation plays an important role in chronic asthma. One of the major mechanisms by which glucocorticoids act in asthma is by reducing airway inflammation and immune activation. However, patients with steroid resistant asthma have higher levels of immune activation in their airways than do patients with steroid sensitive (SS) asthma. Furthermore, glucocorticoids do not reduce the eosinophilia or T cell activation found in steroid resistant asthmatics. This persistent immune activation is associated with high levels of IL-2, IL-4 and IL-5 in the airways of these patients (Health-cares.net, 2005). Factors Influencing Asthma Researchers have identified a number of factors that may increase your chances of developing asthma. Some of the common factors are living in a large urban area, especially the inner city, which may increase exposure to many environmental pollutants, exposure to secondhand smoke or passive smoking, exposure to occupational triggers, such as chemicals used in farming and hairdressing, and in paint, steel, plastics, and electronics manufacturing, having one or both parents with asthma, respiratory infections in childhood, low birth weight, obesity and conditions such as gastroesophageal reflux disease (GERD) (MFMER, 2004). Dietary Factors Certain aspects of the diet that have been discussed in relation to an increased risk of asthma have included a low intake of vitamins C and E. Other diets associated with increased risk of asthma are diets low in vegetables, milk, fibre and calcium. A diet high in fat intake has been suggested to be related to increased risk of diagnosis of asthma. The specific type of fat may also be of relevance, for instance high consumption of oily fish was found to be associated with reduced risk of asthma in children (IEH, 2004). Environmental Triggers of Asthma An environmental pollutant may affect asthma severity in ways such that the pollutant might act as an inciter or trigger, leading to an asthma attack in an individual with hyperresponsive airways. These pollutants can exacerbate preexisting airway inflammation, leading to increased airway hyperresponsiveness, which may persist after cessation of exposure. The pollutants might also augment or modify immune responses to inhaled antigens or intensify the impact of other pollutants in the respiratory tract. Indoor Air Pollution The primary indoor air pollutants associated with asthma exacerbation include biologic allergens, such as those derived from dust mites, cockroaches, and animal dander. The allergen-containing secretions dry on fur, bedding, and clothes and become airborne. The results from The Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994, evaluated children from the age of 2 months to 5 years in the United States. Within this group, approximately 38% of the children surveyed were exposed to ETS in the home, and 23.8% had been exposed to Environmental Tobacco Smoke (ETS) by maternal smoking during pregnancy. Exposure to ETS was associated with three or more episodes of wheezing among children 2 months to 2 years old, and it was associated with asthma among children 2 months to 5 years old. In homes where 20 or more cigarettes were smoked daily, the adjusted odds ratio for asthma was 2.1 for children 2 months to 5 years old. Besides improperly used or malfunctioning heating devices is a major source of combustion pollutants in the indoor environment. Pollutants such as gas ranges especially if used for home heating, improperly vented fireplaces, inefficient or malfunctioning furnaces, wood or coal stoves, unvented or improperly vented kerosene or gas space heaters etc. acts as trigger asthmatic attack. The combustion products from these heating devices include carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter, and SO2. Outdoor Air Pollution For the last several decades, high levels of outdoor air pollution have been associated with short-term increases in asthma morbidity and mortality. For people with asthma, SO2, sulfuric acid aerosols, and NO2 can exacerbate respiratory symptoms in the short term. Exposure to motor traffic emissions can have a significant effect on respiratory function in children and adults. Six pollutants O3, SO2, NO2, CO, lead, and PM10 and PM2.5 [particulate matter ≤ 10 or 2.5 micrometers in aerodynamic diameter, respectively] play a major role as trigger for asthma attack. As an airborne irritant, O3 (ozone) exerts much of its effect on the trachea and bronchi. Because of its high solubility, SO2 irritates primarily the upper airway. The nasal mucosa effectively removes most inspired SO2 during breathing at rest, but deep penetration to the lung mucosa can occur during moderate exercise. SO2 is the only regulated outdoor air pollutant that has a dose-response association with bronchoconstriction. The amount of SO2-induced bronchoconstriction is dependent on the level of preexisting hyperresponsiveness, so a person without asthma can tolerate a higher concentration of SO2 before developing symptoms. Most NO2 health effects are believed to be due to long-term low level outdoor exposure, in contrast to O3 , which causes immediate health effects. Research demonstrated decreased lung function in people with asthma who are exposed to NO2 concentrations above 0.3 ppm. Although NO2 is capable of increasing bronchial responsiveness, no consistent evidence exists to suggest that increasing ambient levels contribute to asthma exacerbations. Particulate matter is a mixture of solid particles and liquid droplets. PM10 is the respirable portion of particulate matter that results in lower airway exposure. PM2.5 is referred to as "fine-particle pollution." Ambient hazardous air pollutants including aldehydes; metals; isocynates; and allergens including soy dust, grain dust from harbor ports, and pollen have been shown to cause asthma among occupationally exposed adults (ATSDR, 2005). Social and Geographical Factors Studies have shown that the prevalence of asthma is not consistently related to socioeconomic status, but a few studies have shown that severe asthma may be more frequent in the poorer groups of society. Asthma mortality is higher in the poor, in Hispanics and black subjects in the USA, and in Britain in those in social classes IV and V or without access to a car (Tauleria and Rona, 1999). Rates of asthma varied markedly with the childs sex; boys had twice the rate of asthma as girls. In addition, the factors associated with asthma varied with the childs sex. For boys, wheeze during infancy, early eczema, and parental asthma were all significant risk factors; for girls, the only risk factor was early eczema. Proportional hazards modeling of the data failed to show any significant associations between the development of asthma and a large range of other social and familial factors including breast-feeding, parental smoking habits, pets in the childs family, stress in the family, or family social background. It was concluded that asthma in early childhood appeared to be inherited to some extent, its age of expression was related to the childs sex, and it had a complex interaction with other forms of allergic disease (Horwood, et.al. 1985). A two-year study on asthma among approximately 4300 school children in the New York City area revealed that overall, in the age group 13–17 years, the asthma prevalence among males is found to be slightly higher than that of females. When comparing rates of asthma incidence among various racial groups, Blacks and Hispanics are found to have higher asthma rates than whites or Asians. Besides, this study also revealed a high asthma occurrence among the economically backward class (Rob, 2003). Further studies need to be conducted in order to study the geographical factors that influence asthmatic attacks or the prevalence of asthma in particular regions. Conclusion Asthma is a chronic condition that usually requires continuous medical care. Medication therapies are designed to minimize the airway inflammation component of asthma as well as to treat airway narrowing. Patients with moderate to severe asthma have to take long-term medication daily (for example, anti-inflammatory drugs) to control the underlying inflammation and prevent symptoms and attacks. If symptoms occur, short-term medications (inhaled short-acting beta2-agonists) are used to relieve them. Medication is not the only way to control asthma. Environmental control measures are also important to avoid or eliminate factors that induce or trigger asthma flare-ups. Allergy test results can help individual become aware of and avoid their personal asthma triggers. Although asthma symptoms may be mild for most people, failure to use appropriate drugs or comply with treatment, coupled with an under-recognition of the severity of the problem, can lead to unnecessary deaths, most of which occur outside hospital. References Health-cares.net, (2005). All about asthma. [online]. Available from: [Accessed 4 January 2006]. Mayo Foundation for Medical Education and Research (MFMER) (2004). Asthma. [online]. Available from: [Accessed 4 January 2006]. IEH (2004) A Review of Potential Causative Factors for Asthma (Web Report W16), Leicester, UK, MRC Institute for Environment and Health, [online]. Available from: [Accessed 6 January 2006]. Agency for Toxic Substances and Disease Registry (ATSDR), (2005) Environmental Triggers of Asthma-Environmental Factors, Sources and Pollutants [online]. Available from: [Accessed 6 January 2006]. E Duran-Tauleria, R J Rona, (1999). Geographical and socioeconomic variation in the prevalence of asthma symptoms in English and Scottish children. Thorax 1999; 54:476-481 ( June ) [online]. Available from: [Accessed 6 January 2006]. Horwood, LJ, Fergusson DM and Shannon FT, (1985) Social and familial factors in the development of early childhood asthma. Official Journal of the American Academy of Pediatrics. Volume 75, Issue 5, pp. 859-868. [online]. Available from: [Accessed 6 January 2006]. Rob, MA, (2003). Applications of Geographical Information Systems in Understanding Spatial Distribution of Asthma. Informing Science Journal, Volume 6: 89-99. [online]. Available from: [Accessed 6 January 2006]. Read More