Asthma Pathophysiology, Treatment, and Community Management

Pathophysiology of Asthma

Asthma is a complex chronic inflammatory disease involving several inflammatory cells, more than a hundred distinct mediators of inflammation, and various inflammatory outcomes — including plasma exudation, bronchoconstriction, activation of sensory nerves, and hypersecretion of mucus. Mast cells contribute immensely to the mediation of acute asthma symptoms; T-helper 2 cells, eosinophils, and macrophages, on the other hand, cause airway hyperresponsiveness by inducing chronic inflammation. An increasing number of researchers have recognized that structural airway cells — including smooth muscle and epithelial cells — are a major source of inflammatory mediators. Asthma involves several such mediators, including growth factors, peptide and lipid mediators, chemokines, and cytokines. Chemokines play a crucial role in the selective recruitment of inflammatory cells from circulation, while cytokines coordinate chronic inflammation, which may cause structural airway modifications such as angiogenesis, sub-epithelial fibrosis, mucus hyperplasia, and airway smooth muscle hyperplasia and hypertrophy (Zaoutis, n.d.).

Patients experiencing persistent or worsening respiratory distress during asthma episodes require hospitalization, as do patients who need essential continuous asthma treatment that cannot be consistently carried out following discharge. Chronic or increasing asthma symptoms despite bronchodilator treatment are termed status asthmaticus. The goals of hospitalization are described from several perspectives: controlling status asthmaticus; stabilizing and improving asthma-related respiratory symptoms through appropriate respiratory support escalation or de-escalation; monitoring and medication; investigating and managing asthma comorbidities or triggers; and planning for patient discharge. A patient's asthma history should be reviewed, and post-discharge home-care plans for both acute exacerbation episodes and long-term maintenance should be recommended, with alterations made when required. Both patients and their families are required to receive asthma education. Patients should also meet with the subspecialty or primary medical team to discuss appropriate follow-up after discharge (Zaoutis, n.d.).

Standards of Practice for Asthma Management

Clinical practice guidelines set by the National Asthma Control Initiative provide a solid foundation for standards of practice. There are four general components involved in these standards: measuring and monitoring, patient education, control of environmental factors, and pharmacologic therapy. The first component is the assessment and monitoring of asthma in individuals. According to the guidelines, "the functions of assessment and monitoring are closely linked to the concepts of severity, control, and responsiveness to treatment" (National Heart, Lung, and Blood Institute, 2007). The severity of an individual's expressed asthmatic symptoms serves as a baseline for future treatments and control measures. Severity often needs to be measured before treatment can be decided upon, and may require the patient to pause control therapy temporarily in order to assess the true level of asthma, since severity is frequently masked by ongoing control therapies. Tests for severity include "spirometry, especially forced expiratory volume in 1 second (FEV1) expressed as a percent of the predicted value or as a proportion of the forced vital capacity (FVC), or FEV1/FVC" (National Heart, Lung, and Blood Institute, 2007).

It is critical for healthcare professionals to understand true severity in order to identify potential risk factors and mitigate them with appropriate long-term control care. This leads to the concept of control factors in standard asthma practice. The guidelines suggest that control relates to "the degree to which manifestations of asthma — symptoms, functional impairments, and risks of untoward events — are minimized and the goals of therapy are met" (National Heart, Lung, and Blood Institute, 2007). Physicians and healthcare professionals consistently monitor control factors in order to gauge the success and efficiency of particular treatments within an individual's care regimen. Additionally, the monitoring standard of care includes assessing responsiveness — how well a particular patient responds to treatments. Like control monitoring, this must be actively and consistently tracked in order to detect any potential failures before they become major risk factors.

The next standard of practice, following diagnosis and monitoring, is patient education. Within standard care practices, it is critical for healthcare professionals to evaluate how well a patient can manage asthma independently, in order to create the most tailored approach to asthma management. "Successful management of asthma requires that the patient or patient's caregiver have a fundamental understanding of and skills for following the therapeutic recommendations, including pharmacotherapy and measures to control factors that contribute to asthma severity" (National Heart, Lung, and Blood Institute, 2007). Physicians must assess each individual patient's capacity to understand their asthma and manage it appropriately before establishing a care regimen. When patients are unable to understand the scope and severity of their condition — as is often the case for very young children or older adults — it is critical that the healthcare team work with caregivers to educate them so they can manage asthma symptoms and controls on the patient's behalf. The Education for a Partnership in Asthma Care framework provides a detailed assessment tool for evaluating patient capability and educating patients or caregivers accordingly.

Finally, there is the component of controlling environmental factors. Physicians and healthcare professionals are required to help mitigate potential environmental factors that may worsen a patient's asthmatic severity. This often requires allergy testing and lifestyle counseling on how to avoid activities or environmental stimuli that would trigger an asthma attack. Exposure to particular allergens — such as pet dander and pollen — and other irritants — such as tobacco smoke and industrial pollution — all contribute to the severity of a patient's asthma. Physicians must help patients evaluate their lifestyles in order to reduce exposure to these environmental factors as a means of better controlling asthma symptoms and severity.

Pharmacological Treatments

There are a number of pharmacological treatments recommended by the accepted standards of care. "The current concept of asthma therapy is based on a stepwise approach, depending on disease severity, and the aim is to reduce the symptoms that result from airway obstruction and inflammation, to prevent exacerbations, and to maintain normal lung functioning" (Rabe & Schmidt, 2001). Beta2-adrenoceptor agonists and glucocorticoids are commonly used in modern practice and are often considered among the more effective drugs for treating inflamed airways in the lungs. Treatment regimens also include a second line of theophylline, leukotriene receptor antagonists, and anticholinergics to augment beta2 treatments (Rabe & Schmidt, 2001). Newer treatments gaining favor include inhaled steroids, "primarily with long-acting beta2-adrenoceptor agonists" (Rabe & Schmidt, 2001). Asthma is a serious condition, but one that can be controlled by following the standard practices established by leading asthma researchers and advocates. By utilizing such control methods, individuals with asthma "can stay active, sleep through the night, and avoid having their lives disrupted by asthma attacks" (National Heart, Lung, and Blood Institute, 2007).

Magnesium sulfate was recommended for use after one hour of treating both mild and life-threatening asthma, administered over a period of more than 20 minutes. The drug is administered infrequently (Vincent, 2014). Magnesium sulfate has been shown to inhibit the contraction of smooth muscle, decrease the release of histamine in mast cells, and prevent the release of acetylcholine. Studies conducted in both children and adults show varying levels of improvement in patients with severe airflow limitation who are unresponsive to conventional treatment using beta agonists, corticosteroids, and anticholinergic medications (Rowe & Camargo, 2008).

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