Asthma - Etiology, Clinical Findings, Signs and Symptoms - Research Paper Example

Asthma al Affiliation Background: Asthma is an inflammatory disease of the airways that causes narrowing of the airways causing to obstruction of airflow leading to symptoms such as wheezing, dyspnoea, chest tightness and coughing. Asthma affects the quality of life of the patients and is and is an economic burden to the families due to medical expenses and hospitalisations. Asthma is prevalent in westernised environments as compared to rural areas. Aims and objectives: To identify ways in which asthma can be caused, its pathophysiology, prognosis, epidemiology, signs and symptoms, diagnosis, treatment, prevention and management. Proper management of the disease will enable patients live a better quality of life with fewer hospitalisations. Keywords: Asthma, allergens, inflammation, wheezing Introduction Asthma is an episodic and chronic inflammatory disease of the small airways of the lungs, characterised by intermittent airway narrowing and airflow obstruction that leads to symptoms of recurrent episodes of wheezing and shortness of breath, chest tightness and coughing particularly at night and early in the morning. (Goyal & Agrawal, 2013) It causes a heavy economic burden on patients, their families and the healthcare system. It is a burden to low-income earners due to medical and drug costs. Asthma patients experience missed school or work days, medical expenses and even premature death therefore influencing their quality of life. Knowledge about the disease and its predisposing causes for development would help researchers to better target future therapies. (Bollmeier, 2013) Pathophysiology Asthma is a complex syndrome characterised by airway hyper-responsiveness and is caused by a multicellular inflammatory reaction that leads to airway obstruction. Inflammatory and cellular infiltration of the airways is by recruitment and activation of mast cells, macrophages, antigen presenting dendritic cells, neutrophils, eosinophils and T lymphocytes. The major role in the activation of the immune system that leads to the release of many mediators such as interleukins and granulocyte macrophage colony stimulating factor is by type 2 T helper cells. Cells and tissues in asthmatics are prone to inflammatory reactions against normally harmless substances. This inflammation can cause swelling, mucous production leading to airway narrowing. Air narrowing leads to asthma triggering symptoms. Exposure to substances that trigger reactions on the airways lead to production of IgE antibodies that help release of inflammatory mediators such as histamine and leukotrienes. These mediators cause the airway of the smooth muscles to contract. Some mediators activate B lymphocytes to produce immunoglobulin E (IgE) while others are related to eosinophilic bronchitis, neutrophilic infiltration of the airway and a pauci-granulocytopenic type of inflammation. This persistent inflammation results in airway remodelling which includes increased deposition of extracellular proteins, smooth muscle hypertrophy and hyperplasia and increased goblet cells. This leads to the epithelium being fragile and thin and the epithelial basement membrane thickens. There would be increased mucus production and endothelial leakage which leads to mucosal oedema. Mediator induced abnormalities in the parasympathetic and non-cholinergic nervous system may lead to increased bronchial hyper responsiveness. (Al-Moamary, et al., 2012) In places with extremely clean household environments and fewer circulating infectious diseases have higher incidences and prevalence of asthma meaning the immune system is not challenged. The developing immune system shifts the balance between equal parts of T-helper (Th) cells type 1 and type 2. The lack of exposure bacteria shifts the immune system toward a Th 2 cell mediated immunity. The shift favours the development of allergic disorders including asthma because Th 2 cells produce interleukins that contribute to atopy through immunoglobulin E production. Etiology Atopy and environmental triggers are general etiologic factors that predispose a person to asthma. A rural lifestyle is consistently associated with a low prevalence of asthma. Exposure to farm animals and drinking of unpasteurised milk is protective in farmers’ children. In urban environment presence of pets in the house and large family sizes are protective in children reared in an urban environment. Allergies and sensitivities underlie many cases of asthma. An allergy is an appropriate immune response against an innocuous compound. A wide variety of environmental allergens can cause an asthma attack including food allergies. Chronic, low level inflammatory reactions triggered by an immune response to food particles may set the stage for airway inflammation. Those with asthma will produce high levels of IgE antibodies to the particular foods. Exposure to allergens such as pollens and dust, inhalation of tobacco smoke, the presence of air pollution and obesity can trigger or predispose a person to asthma. Indoor allergens include mould, dust mites, animal dander and cockroaches. Pets maybe allergenic unless if the child has no family history of allergic diseases. Both active smoking and exposure to second hand smoke are triggers of asthma symptoms. The onset of paediatric respiratory illness may begin during foetal development. Exposure to tobacco smoke early in life diminishes airway function and decreases lung growth. Those reductions cause changes in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and maximal mid expiratory flow. Infant wheezing is linked to maternal smoking. Exposure to high levels of air pollution such as nitrogen dioxide, ozone, particulate matter generated by industry and vehicle traffic triggers exacerbations. (Bollmeier, 2013) A variety of common viral infections acquired during infancy and early childhood appear to increase the risk of childhood wheezing episodes that may eventually lead to asthma. Respiratory tract infections such as viral URI illnesses, sinusitis, bronchitis and medical problems such as GERD, depression and rhinitis are common asthma triggers. Occupations commonly associated with asthma include woodworking, detergent manufacturing, some health care professions, baking flour and paint. Some medications including non-steroidal anti-inflammatory drugs, certain aspirin and ACE inhibitors can trigger an asthma attack in some people. (Kesterson, et al., 2010) Epidemiology Many studies investigating the prevalence of asthma in various countries have focused on children below 15 years of age or adults above 18 years. The most common form of the disease is atopic asthma and is predominant in the western world. Asthma affects one cild in 7 in some society and approximately 15 million individuals worldwide. Clinical findings The natural history of wheeze is dependent on age at first presentation. The earlier the onset of wheeze, the better the prognosis. Most children who present before two years become asymptomatic by mid childhood. Co-existent atopy is a risk factor for persistence of wheeze independent of age presentation. In pre-pubertal children male sex is a risk factor for asthma while female sex is a risk factor for the persistence of asthma in the transition from childhood to adulthood. Frequent or severe episodes of wheezing in childhood are associated with recurrent wheezing that persists into adolescence. (Scottish Intercollegiate Guidelines Network, 2012) Prognosis Current asthma prevalence is higher in children than adults indicating that children with asthma may outgrow their disease. The prognosis for asthma occurring in infancy or childhood is good and in most of them the symptoms would resolve at puberty. Non-smoking individuals with asthma have good prognosis despite some reduction of lung function in those with severe symptoms. In very severe asthma more than 50% of the patients develop irreversible obstructions, whereas the prognosis of lung function in the great majority of children and adults with asthma is quite favourable. (Lange, 2013) The clinical manifestations of diagnosed childhood asthma may change over time due to changes in diagnostic practices, risk factor patterns and lifestyle, necessitating repeated monitoring of remission rates and predictive factors. (Andersson, et al., 2013) The prognosis of asthma is challenging because no absolute indicators are available. The presence of risk factors is used to predict the persistence of childhood asthma into adulthood. (Bollmeier, 2013) Signs and symptoms Asthmatic symptoms include recurrent episodes of wheezing, chest tightness, shortness of breath (dyspnoea), and coughing. These symptoms are not always present at the same time and are not diagnostic. However recurrent symptoms especially those provoked by exogenous factors would suggest asthma. Asthma would be indicated by nocturnal cough, exercise induced cough or wheezing. Onset of symptoms after exposure to airborne allergens or other stimuli would indicate asthma. History of respiratory tract infections with lingering cough and conditions associated with asthma such as atopic dermatitis and rhinitis are symptoms of asthma. Multiple symptoms of asthma reflects uncontrolled disease and can be a sign of more severe asthma. Care of the patients relies on the symptoms. Signs that would indicate asthma include evidence of bronchial obstruction, wheezing, prolonged expiration, at least partially reversible airway obstruction. Atopy would be indicated by swollen and discoulored nasal mucosa, clear nasal discharge, partial nasal airway obstruction, erythematous conjunctiva, palpebral cobblestonning and tearing. The skin will have signs of atopic dermatitis. (Kesterson, et al., 2010) Diagnosis The criteria for diagnosis of asthma are not reliably understood and effectively applied. The disease is often under diagnosed or diagnosed inaccurately. The symptoms of asthma, that is, cough, wheezing, dyspnoea and chest tightness may not always be present and may not be diagnostic but if they are recurrent especially when provoked by exogenous factors would be a possibility of asthma. Recurrent or prolonged isolated cough without any discernible cause is consistent with asthma. Diagnosis in children under 4 years especially is wheezing, cough and difficulty in breathing in infants. Therefore a young child who has had more than two episodes of asthma symptoms in a year should be treated for asthma and the response to the treatment monitored. Parental history of asthma, presence of atopic dermatitis, sensitization to aeroallergens or foods, presence of greater than or equal to 4 percent of blood eosinophilia would help in diagnosis. (Kesterson, et al., 2010) The initial clinical assessment of diagnosis of asthma is based on identifying a characteristic pattern of episodic respiratory symptoms and signs. If the patient experiences frequent and recurrent wheezing, coughing, difficulty in breathing and chest tightness, are worse at night or early in the morning and occur in response to exercise or exposure to pets, cold or with emotions increase probability of asthma. Conventional lung function testing is possible on patients above five years of age. This includes measures of airway obstruction, reversibility with bronchodilators and airway hyper-responsiveness. (Scottish Intercollegiate Guidelines Network, 2012) Spirometry is used to detect airflow obstruction, assess severity, and demonstrate significant reversibility. It may help to identify other differential diagnoses such as large airway obstruction. However, normal spirometry does not rule out the diagnosis of asthma. Serial peak expiratory flow (PEF) is helpful in asthma diagnosis and follow up. Inhaled corticosteroids and bronchodilator may be useful in confirming diagnosis. Chest X-ray is only recommended when diagnosis is in doubt. Peripheral eosinophilia and elevated IgE level are supportive of the diagnosis. To identify allergens which the patient is sensitive to is done by skin testing and radioallergosorbent test therefore in helping strategy for avoiding allergy exposure. (Al-Moamary, et al., 2012) Alternative diagnoses to consider in children include large airways which may be characterised by foreign body, vocal cord dysfunction, vascular ring, laryngeal web, laryngotracheomalacia, tracheal stenosis, bronchostenosis, enlarged lymph nodes and tumour. In adults, the diagnoses would include heart failure, chronic obstructive pulmonary disease, pulmonary embolism, tumor, GERD and Eosinophilic infiltration of the lung. (Kesterson, et al., 2010) Treatment Asthma is controlled pharmacologically in a stepwise fashion depending on severity of symptoms to achieve and maintain control of the disease. Asthma medications used to treat acute symptoms of an asthma attack are called quick relief medications while long term control medications are used to prevent further exacerbations. The goal of the treatment is to optimise long term control so that quick relief medications which have many side effects may be minimised or eliminated. Relievers are medications that act quickly to reverse bronchoconstriction and relieve symptoms. Inhaled corticosteroids are the most effective anti-inflammatory medications for the treatment of asthma. They reduce symptoms, improve on the quality of life, improve lung function, control airway inflammation, reduce frequency severity of the exacerbation and reduce asthma mortality. However, adverse effects can occur and include oropharyngeal candidiasis and dysphonia. Metered dose inhalers may help reduce these effects. Mouth washing after inhalation may help reduce oral candidiasis. When long acting B2-agonists that is formoterol and salmeterol should be used together with inhaled corticosteroids to improve on the symptoms. There is decreased nocturnal asthma, improved lung function, decreased use of rescue rapid onset inhaled B2 agonists, reduced number of exacerbation and more clinical control of asthma. Fixed combination inhalers are available in the form of fluticasone and salmeterol or budesonide and formoterol and are more considered by patients. They provide longer protection to prevent exercise induced bronchospasm. Their side effects include tachycardia, tremor, headaches, muscle cramps and hypokalemia. Leukotriene modifiers reduce airway inflammation and improve asthma symptoms and lung function but less consistent effect on exacerbations. Theophylline is a weak bronchodilator with anti-inflammatory properties and provide benefits as add on therapy in patients who do not achieve control with inhaled corticosteroids alone. Anti-IgE use is indicated for patients of 12 years and above with severe allergic asthma uncontrolled on high dose inhaled corticosteroids and other controllers who have an IgE level in the appropriate therapeutic range. (Al-Moamary, et al., 2012) When ketamine is administered in asthmatic patients it has been proven it acts a bronchodilator and helps relieve wheezing. Ketamine not only protects against precipitation of asthma in asymptomatic group but alleviates bronchospasm in patients with distress prior to induction of anaesthesia. Ketamine may also be useful in treatment of bronchospasm during mechanical ventilation. Ketamine can also be used safely for post-operative analgesia in asthmatic patients. Ketamine is a versatile and inexpensive drug and has been found to obviate the need for mechanical ventilation. (Goyal & Agrawal, 2013) Management of asthma Identification of patients at high risk of exacerbation can improve asthma outcomes and decrease costs by leading to improved asthma care. Better quality of care of asthma for a particular population can be assessed by survey data and administrative data. In patients with severe attacks of asthma, the rate of endotracheal intubation reduced after introduction of non-invasive ventilation without worsening the prognosis of the disease. (Murase, et al., 2010) Some patients’ ability to perceive the severity of their symptoms is poor resulting in treatment delay. Patients should be educated on an overview of the mechanism, triggers, signs, medications, metered dose inhaler use, indicated monitor peak expiratory meter flow rates use and how to self-medicate in case of acute exacerbation. Patients can prevent exacerbation by adhering to controller drug regimens and avoiding known triggers. (Bollmeier, 2013) Self-management is fundamental to successful therapy. Patients with severe asthma and whose perception of their symptom is poor should measure PEFR at home, compare it to their personal best peak flow and modify therapy or seek help as indicated. (Kesterson, et al., 2010) A continuous process with periodical assessment of asthma control combined with adjustment to pharmacotherapy based on the level of control. It is recommended to use asthma pharmacotherapy in a stepwise approach with the ultimate goal of achieving optimal control with minimal amount of medications and dosage. Compliance to and proper use of the prescribed medications and their devices is recommended to be addressed before any modification treatment plan. It is recommended to be provided to patients and their caregivers and includes medications, their doses and technique. Action plan would include information for patient and caregiver on how to recognise worsening of asthma symptoms and advices of treatment modification in these situations. Eliminating exposure to allergens, viral infection, pollution and drugs would help control asthma and reduces medication needs. (Al-Moamary, et al., 2012) Indoor allergens should be removed for instance, washing bedding in hot water and encasing pillows. Removal of animals to which the patient is allergic from the patient’s environment is important. Conclusion Asthma is a disease that affects the normal activity of patients and cause of mortality in some people. Therefore it is important to ensure proper diagnosis, identification of the triggers, effective treatment and management of the disease. Asthma therapies aim to reduce inflammation and improve airway function. Controlling asthma symptoms at rest and during exercise, attaining normal lung function and minimising adverse drug reactions, preventing exacerbations, attaining normal activity levels including exercise and preventing unscheduled office visits, emergency visits and hospitalisations improve the quality of life of the patient. References Al-Moamary, M. S., Alhaider, S. A., Al-Hajjaj, M. S., Al-Ghobain, M. O., Idrees, M. M., Zeitouni, M. O., . . . Alorainy, H. S. (2012). The Saudi iniatiative for asthma - 2012 update: Guidelines for the diagnosis and management of asthma in adults and children. Annals of Thoracic Medicine, 175-204. Andersson, M., Hedman, L., Bjerg, A., Forsberg, B., Lundback, B., & Ronmark, E. (2013). Remission and Persistence of Asthma followed from 7 to 19 years of age. AmericanAcademy of Pediatrics. Bollmeier, S. G. (2013). New Tharapies in Asthma. ACSAP : Pulmonary and Preventive Care, 1-31. Goyal, S., & Agrawal, A. (2013). 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