Introduction
Case studies on different manifestations of asthma highlight the seriousness of the disorder and the need for its treatment with the urgency it deserves. The sudden development of Asthma in initial normal patients and the sudden death in most cases justifies understanding of the pathophysiological mechanisms of the different forms of asthma. The importance of recognizing symptoms of the disease and categorizing them based on the level of seriousness on the prescription of effective treatment cannot be understated. According to the CDC (2011), asthmatic persons can be symptom-free upon the institution of appropriate medical care and mitigation of trigger factors in the environment. However, such is not the case for healthcare sectors worldwide face challenges in providing appropriate diagnostic resources. Consequently, the prevalence rates of diagnosed asthma, clinically treated asthma, and wheezing rose worldwide. According to the CDC (2011), the prevalence rates for persons of all ages in the US rose from 7.3%, representing 20.3 million people in 2001, to 8.2%, representing 24.6 million people in 2009. The prevalence rate among children (persons aged ≤18) was 9.6%, and 7.7% among adults. The figures are above the estimates posited in Huether and McCance (2017), but closely resemble those in Hammer and McPhee (2014). Nevertheless, they corroborate the argument about the rising trend in prevalence rates. The association of asthma with a disability, excessive utilization of health resources, and low quality of life is a cause for concern among all stakeholders. Access to healthcare, appropriate medication, self-management skills, and evidence-based practices for reducing environmental risk factors is founded on effective diagnosis. The purpose of this paper is to describe the pathophysiological mechanisms of chronic asthma and acute asthma exacerbation, the role of age in pathophysiology, diagnosis, and prescription of treatment, and construct mind maps for the management of the two forms of asthma.
The Pathophysiological Mechanisms of Chronic Asthma and Acute Asthma Exacerbation
Asthma is a disorder that causes chronic inflammation of the airways and is characterized airway hyper-responsiveness, episodic and reversible obstruction of airflow, and underlying inflammation. Chronic asthma and acute asthma exacerbation have similarities in their symptoms and basic treatments but differ about severity and duration of the attack. Acute asthma exacerbation refers to a temporary form of asthmatic attack with severe outcomes, while chronic asthma occurs over a prolonged time and may have less severe outcomes (Hammer & McPhee, 2014). The development of asthma starts in childhood upon sensitization to commonly inhaled allergens such as animal dander, house dust mites, cockroaches, fungi, and pollen ( Kudo, Ishigatsubo, & Aoki , 2013). In all types of asthma, T helper type 2 cells (Th2) proliferate following stimulation by the inhaled allergens. The process causes the production and release of Th2 cytokines, and interleukin IL-3, 4, 5, 6, 9, 10, and 13 (Hammer & McPhee, 2014). Allergens involved in the sensitization can be taken up by antigenic processing dendritic cells for presentation to naïve T helper cells. The process causes activation of allergen-specific Th2 cells responsible for the development and progression of asthma. According to Kudo et al. (2014), there is sufficient evidence on the role of Th17 and Th9 in the modulation of asthma disease given their role in the production of cytokines that cause inflammation of the airways and enhance contractility of smooth muscles.
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The Pathophysiological Mechanisms of Acute Asthma Exacerbation
Acute asthma exacerbation occurs when Th2 cytokines and interleukins activate B-lymphocytes (plasma cells) and eosinophils. Plasma cells react by producing antigen-specific IgE with an affinity for mast cells surface. The interaction causes degranulation of mast cell and release of inflammatory mediators that are responsible for vasodilation, mucosal edema, mucus secretion from the mucosal goblet, increased permeability of the capillaries, and obstruction and narrowing of the airways. Simply put, acute asthma exacerbation is triggered by the binding of an inhaled antigen to a mast cell that has undergone IgE. Degranulation of such mast cells following the cross-linking releases histamines, bradykinins, interleukins, prostaglandins, leukotriene, and platelet-activating factor that serve as inflammatory mediators. Dendritic cells are responsible for the detection of the inhaled antigen, signaling the release of interleukin -4 by Th2 and other cells. The interleukins mediate the production of IgE by B cells. Th2 cells can produce IL-5 responsible for stimulation of eosinophils, with the capacity to create copious amounts of protein and eosinophilic cationic protein that are potentially damaging to the respiratory epithelium (Hammer & McPhee, 2014). Various inflammatory cells are responsible for inflammation and obstruction of the airway in acute asthma exacerbation.
The Pathophysiological Mechanisms of Chronic Asthma
According to Hammer and McPhee (2014) chronic asthma is characterized by increased sensitivity to type 2 inflammation and viral infection, bacterial colonization, or impaired lung development. In this type of asthma, dendritic cells, lymphocytes, mast cells eosinophils, T helper two cells, B lymphocytes, neutrophils, and basophils are involved in the promotion of intractable bronchial mucosa inflammation and airways hyper-responsiveness (Hammer & McPhee, 2014) . Symptoms such as airway remodeling manifested by thickening of all compartments of the airway wall can be observed in chronic asthma and have significant impacts on the narrowing of the airways, hence determines chronicity of the disease. The remodeling process is driven by the production of growth factors, TGF-β, TGF-α, and fibroblast growth factor (FGF), by macrophages, epithelial cells, and other inflammatory cells ( Huether & McCance, 2017 ).
Impacts of Age on the Pathophysiology of Asthma
Previous studies demonstrate the high rates of prevalence of asthma in children compared to adults. According to the CDC (2011), children have the highest rates of asthma than any other age group. The findings are corroborated by Huether and McCance (2017) that younger males below the age of 18 years have a high prevalence (10.2%), while females aged over 18 years were also noted to be prone to the disease. There is no literature on the age-based comparison in the development and progression of the two types of asthma. However, the risk factors discussed in Huether and McCance (2017) offer insights into the role of age in the pathophysiology of asthma. Asthma develops early in childhood during sensitization to allergens. The Asthma and Allergy Foundation of America (2018) noted that asthma is a common chronic disease that affects children in the US. The disease is also common among adults over 65 years of age and can have serious health implications if left untreated.
About the pathophysiology of asthma, children are more vulnerable because of the smaller airways compared to adults. The Asthma and Allergy Foundation of America (2018) observed that the small nature of airways in children, any small amount of swelling caused by the reactions triggered by the antigen, viral infection, or constriction could have adverse effects. Viral infections are the main triggers of acute asthma exacerbation in children. Children with acute asthma exacerbation face an increased risk of developing chronic asthma. Childhood exposure to triggers is theorized to alter adaptive immunity and promote the development of factors responsible for atopy (Hammer & McPhee, 2014). On the other hand, the elderly population is the fastest growing population group in the US, which makes it central to in the management of asthma. A significant number of asthmatic adults develop the condition at a young age, but asthma can occur at any age. Adults are at a heightened risk of developing asthma because they are exposed to increased risk factors in their environments of operations. Adults are more vulnerable to smoking, obesity, respiratory infections, allergens, and air pollution that act as triggers of the disease. Older patients with the types of asthma have shown similar symptoms as children, but unlike in young children where the disease can go into remission, asthma in adults can remain potentially serious, progressing into a disabling illness.
Impact of Age on Diagnosis and Treatment of Asthma
Inflammation of the airways is a critical feature in the diagnosis, management, and prevention of asthma (CDC, 2011). However, diagnosis is young children is often difficult because patients are unable to communicate when experiencing the initial problematic symptoms. Also, asthma has symptoms that are closely related to other respiratory illnesses. Close monitoring of children for signs and symptoms of the disease is necessary to ensure prompt treatment and management. Diagnosis of asthma in children is dependent on factors such as family history of the disease or allergies, overall behavior, breathing patterns and changes, responses to foods, and possible observed triggers. Observation of response to treatment may also be used to diagnose asthma in children. Young children can take medications prescribed for older patients in lower doses, but inhalers are preferred because they are easy to administer and are fast acting. Administration of medications in children is done using nebulizers with facemasks, or an inhaler with a facemask. Therefore, formulations of medications such as albuterol for opening airways, and steroids for long-term elimination of symptoms must take into consideration the mode of administration in children.
In older children and adults, pulmonary function tests are routinely done to detect asthma (Asthma and Allergy Foundation of America, 2018). However, diagnosis of asthma in adults presents challenges because the disease symptoms may be masked by symptoms of other present conditions. Asthma in older patients is usually characterized by a productive cough. Symptoms such as wheezing, dyspnea, cough, or intolerance to exercise that are common in children are used to diagnose asthma in adults. Acute asthma attacks in both children and adults require immediate assessment of arterial blood gases and flow rates and the establishment of the trigger (Huether & McCance, 2017). Hypoxemia, alkalosis, and acidosis are evidence of acute asthma attack and the need for mechanical ventilation. Antibiotics must be avoided in the treatment of acute asthma unless the existence of infection in proven. Management of both types of asthma starts by avoidance of allergens and irritants. Extensive education and the use of action plans is recommended and immunotherapy for long-term treatment.
Conclusion
The association of asthma with sudden death in previously undiagnosed cases is a cause for concern. Evidence shows that prevalence rates of chronic and acute asthma are on the rise. Persons aged below 18 years have shown high prevalence rates, though adults over the age of 65 are considered to the most vulnerable. Diagnosis of asthma in children and adult is dependent on observed symptoms, which in some instance, may be due to another present disease. Treatment and management of acute and chronic asthma entail avoiding triggers and allergens, chemotherapy, and immunotherapy. However, the mode of administration of therapies in children and adults vary.
References
Asthma and Allergy Foundation of America. (2018). Asthma in infants and young children. Retrieved from http://asthmaandallergies.org/asthma-allergies/asthma-in-infants-and-young-children/
Centers for Disease Control and Prevention (CDC. (2011). Vital signs: asthma prevalence, disease characteristics, and self-management education: United States, 2001-2009. MMWR. Morbidity and mortality weekly report , 60 (17), 547-552.
Hammer, G. G., & McPhee, S. (2014). Pathophysiology of disease: An introduction to clinical medicine . (7th ed.) New York, NY: McGrawHill Education.
Huether, S. E., & McCance, K. L. (2017). Understanding pathophysiology (6th ed.). St. Louis, MO: Mosby.
Kudo, M., Ishigatsubo, Y., & Aoki, I. (2013). Pathology of asthma. Frontiers in microbiology , 4 , 263.
