The Pathophysiology

and Management of Asthma

1. Introduction

Even though scientists have since time immemorial engaged in research aimed at eliminating all diseases from the face of the earth, the fact is that this objective is far from being met. Asthma is one of the major medical conditions believed to affect a large proportion of the people in society, both children and adults. Researchers have made it clear that despite the disease presenting in varying patterns in different people, most of these patterns are related to a particular condition. Information from quite a number of studies suggests the possibility of there existing different lung conditions that can lead to the development of asthma. Acquiring general knowledge with reference to the possible triggers as well as the most effective preventative measures is important for those presenting with asthmatic symptoms. This knowledge as stated by Goroll and Mulley (2009) empowers not only sufferers but also other people as far as taking active role in their health is concerned.

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There are numerous myths that have been produced with regard to the causes, prevention and treatment of asthma. Some of these myths are highly misguiding and can potentially aggravate asthmatic symptoms (Lieberman 1999). It is important to enlighten the people concerning the possible measures that can be taken to prevent development of asthma together with reducing the risk of triggering asthmatic symptoms among victims (Platts-Mills 1999). Research has revealed that there are some medical conditions that present with symptoms similar to those of asthma (Lugogo & MacIntyre 2008). In such cases it is important to enquire of the medical history of the patient in order to deal with the underlying causes rather than dealing with asthmatic symptoms only.

1.1 What is Asthma

Asthma is one of the most devastating conditions affecting the respiratory system. This implies that people suffering from this disease are subjected to breathing difficulties every time they are exposed to trigger factors (Adams 2006). When persons presenting with asthma come into contact with substances that irritates their respiratory system, the muscles around their respiratory tract tighten making their airways to become narrower (Levy, Weller & Hilton 2006). There also occurs an increased secretion of sticky mucus, an aspect that makes it hard for one to breathe normally. There are different types of asthma, these include: Asthma triggered by common environmental substances such as smoke and dust, work-aggravated asthma and occupational asthma. Work-aggravated asthma is a pre-existing asthma worsened by presence of fumes and dust particles at the place of work. Occupational asthma, on the other hand, is the type of asthma that occurs as a result of exposure to certain substances at work. Some nurses for instance may develop occupational asthma as a result of exposure to latex (Lieberman 1999).

1.1.1 History of our understanding of asthma

Medical history of asthma dates back to hundreds of years (Braman 2006). Management of asthma remains a major challenge not only to the patient but also to healthcare professionals. Studies have revealed that asthma cannot be cured (Lugogo & MacIntyre 2008). Health practitioners advise people presenting with asthma to stay away from potential triggers of asthmatic symptoms (Levy, Weller & Hilton 2006). Avoidance of possible triggers has been recognized as one of the best ways through which this disease can be managed (Langenfeld, Bonaiuto & Edmonds 2006).

1.2 Epidemiology of asthma

The risk of developing this disease is higher among children who are exposed to trigger factors such as cigarette smoke and also among children who are born with low birth weight (Platts-Mills 1999). It has also been revealed that African American children have a higher risk of developing asthma as compared to their counterparts from other communities. Children who are born in economically unstable families are also believed to have a higher risk of developing asthma. This is because their families do not have the financial capacity to provide them with the much needed medical care (Brown 2003). Children who are born of parents presenting with asthmatic traits are at a higher risk of developing full blown asthma as compared to children who are born of parents who do not have asthmatic traits (Behera, 2005). Research has shown that overweight adults are at a higher risk of developing asthma as compared to normal weight adults (Lugogo & MacIntyre 2008).

1.2.1 Prevalence of asthma

Research has revealed that cases of asthma have been increasing gradually over the years (Levy, Weller & Hilton 2006). The large number of asthma cases among children in the United Kingdom, the United States and other westernized countries can be attributed to changes in the nature of exposures to a variety of factors in the fetal and also in early childhood period (Peacock 2000). Research has revealed that these changes can have a significant influence on the development of the immune system (Peacock 2000). It has also been shown that in persons who are genetically predisposed, alterations in the immune system may lead to an increase in allergic response to foreign matter.

1.2.1.1 Worldwide

It is estimated that there are over 300 million people suffering from asthma all over the world. Approximately 13% of this population is made of sufferers from the United Kingdom. Even though this disease affects people of all ages, the proportion of children presenting with asthmatic symptoms is far much higher as compared to other age brackets (Braman 2006). In the United Kingdom, for instance, it is estimated that there are over 6 million children suffering from asthma. It is estimated that 7% of the entire United Kingdom adult populace suffers from asthma. Asthma is believed to result in global deaths of more than 250, 000 people yearly. Almost 4, 200 cases of deaths occurring in the United Kingdom yearly are believed to occur as a result of asthma and its associated complications (Peacock 2000).

1.2.1.2 Australia

It is estimated that about 10% of the entire population, over two million people, in Australia suffer from asthma. This figure in accordance with international standards shows that asthma prevalence in Australia is high. The risk of developing asthma is much higher among young boys as compared to girls (Barnes, Peter & Godfrey 2000). This is due to the smaller size of young boy’s airways as compared to that of young girls. As a consequence, the risk of wheezing and developing respiratory infections is higher among boys. The trend is, however, believed to revert during adulthood. Indigenous Australians form the largest group of people presenting with asthma as compared to other groups.

2. Pathophysiology and pathology

Research has revealed that there are three main physiological changes that occur as asthma progresses (Kaliner 2003). One of these changes is increased secretion of mucus. Besides clogging the airways, this mucus is believed to impact heavily on an asthmatic person’s breathing. It has also been revealed that in asthmatic conditions the respiratory tract becomes inflamed and swollen. Trigger factors result in swelling of the lungs and respiratory sinuses making it hard for one to breath. Respiratory muscles also tighten thereby resulting in constriction of the airways. In fatal asthmatic conditions, the respiratory tract becomes clogged with tenacious blocks of exudates and mucus in addition to cellular components (Kaliner 2003)

The surface epithelium of the airways becomes weaker and the epithelial reticular basement membrane thickens. These two aspects are believed to compromise on secreting eosinophils and activated T-lymphocytes (Kaliner 2003).

2.1 Physiology of Respiration

The principal function of the respiratory system is exchange of gases. The main gases whose exchange takes place in the respiratory system are carbon dioxide and oxygen. Gaseous exchange involves removal of carbon dioxide from blood and introduction of oxygen to blood. Whereas oxygen is essential for purposes of normal body metabolism, carbon dioxide, which is a waste product of metabolism, can be harmful to the body. The fact that only a small amount of carbon dioxide get into the body through gaseous exchange implies that a large proportion of carbon dioxide released through exhalation is created in the body (Kaliner 2003).

2.1.1 Mechanism of respiration and gas exchanges

The mechanism of respiration is subdivided into two major groups: internal respiration, which is mainly involved in intracellular metabolic processes and external respiration which provides an explanation to the entire process of gaseous exchange between the cells of the body and the external environment. The respiratory cavity and the rib cage are made up of muscles that work in coordination to aid in breathing. Whereas contraction of the diaphragm and external intercostals muscles assist in inspiration, relaxation of the diaphragm and external intercostals muscles assist in exhalation (Saini 2010). The lumen of various respiratory tracts is maintained in an open position to make it possible for free movement of air. Exchange of gases occurs between the walls of the alveoli and small blood vessels. Whereas oxygen diffuses from the alveoli to blood, carbon dioxide diffuses from blood into the alveoli. Saini (2010) makes it clear that carbon dioxide is excreted from the body through the respiratory tract while oxygen is circulated to various body organs through blood. The exchange of carbon dioxide and oxygen between body tissues and blood occurs across the thinnest capillaries.

2.2 Pathophysiology

2.2.1 Aetiology of asthma

Allergies are some of the main potential trigger factors for development of full blown asthma. Almost 90% of the people presenting with asthma are believed to have allergies. Research has revealed that almost 25% of the people presenting with hay fever, also referred to as allergic rhinitis, develop asthma later on (Rees, Kanabar & Pattani 2010). Antibody reactions to certain allergens have been shown to result in inflammation of the airways. There are a variety of outdoor allergens that have been identified as potential triggers for asthmatic conditions.

Tobacco smoke, for instance, is believed to expose a large percentage of people to a higher risk of developing asthma (Koenig & Chesla 2004). It is important to note that tobacco smoke does not only expose people to the risk of asthma, but it also increases their risk of death due to infections in the respiratory system and also due to intense wheezing (Lugogo & MacIntyre 2008).

2.2.1.1 Environmental causes

Some poisonous gases such as sulfur dioxide and nitrogen oxide together with air pollution, for instance, have been shown to trigger asthmatic symptoms (Spear 2002). During periods when air pollution is at its highest level, recorded cases of asthma increase drastically (Yeatts 2006). High level of humidity at home as well as in health facilities increases the risk of developing asthmatic symptoms. Drastic changes in weather have also been shown to have a negative impact on persons presenting with asthma (Yeatts 2006). Cold air, for instance, has been shown to result in congestion of the airways, constriction of the bronchus as well as increased secretion in conjunction with decreased rate of mucocilliary clearance (Spear 2002). Besides aggravating asthmatic symptoms, smoking results in a tremendous deterioration in lung function (Goroll & Mulley 2009). Cigarette smoking is believed to alter the inflammatory response in asthma thereby resulting in reduced response to inhaled corticosteroids. Exposure to second hand smoke has also been shown to negatively impact on the health of asthma patients (Murphy 2007).

2.2.1.2 Genetic causes

Genetic factors are believed to be the major predisposing factors to the development of asthma. More than one hundred genes are related to asthma (Clark 2011). A large number of these genes have been shown to play a major role not only in altering the immune system but also in triggering inflammation. Gene-environment interactions are also presumed to play a part in the development of asthma (Barnes et al 2008).

Behera (2005) makes it clear that excessive consumption of antibiotics is also believed to increase the risk of developing asthma. Some antibiotics usually work through modifying the gut and the respiratory flora. This modification disrupts the immune system modulators and aggravates the risk of developing asthma (Platts-Mills 1999).

2.2.1.3 Exercise causes

Even though exercise is not a real cause of asthma it is believed to poses the capacity to trigger asthmatic symptoms even in persons who have do not have a history of this disease. Asthmatic conditions that are induced by exercise are more severe and highly sensitive to environmental changes as compared to other types of asthmas (Clark 2011).

2.2.2 Airway Inflammation

Inflammation of the respiratory passages is one of the main symptoms of asthma. This inflammation is usually triggered by allergens or exercise which result in an asthmatic attack.

2.2.3 Intermittent Airflow Obstruction

A variety of asthmatic symptoms usually occur as a result of sporadic reversible episodes of obstruction of airflow. These symptoms are manifested clinically by coughing, wheezing, dyspnea and tightness of chest.

2.2.4 Bronchial Hyper-responsiveness

Bronchial hyper responsiveness is usually triggered by contraction of small airways also referred to as bronchioles. Bronchial challenge test is the main test carried out to determine presence of bronchial hyper responsiveness. This test easily triggers bronchospasm in persons with asthma (Levy Weller & Hilton 2006).

2.3 Common Types of Asthma

Health care professionals have classified asthma into four major groups in order to provide maximum care for people presenting with this disease. These groups include: Mild intermittent and mild persistent asthma, moderate persistent asthma and severe persistent asthma

2.3.1 Comparison between severe, moderate and mild asthma

Mild intermittent asthma characterized by at least no more than two attacks per week. The other group is mild persistent asthma characterized by more than two attacks per week. Sometimes these attacks are so severe that they interfere with the normal functioning of a person. Moderate persistent asthma, on the other hand, is characterized by day and nighttime attacks. The attacks occur more than two times every week. Severe persistent asthma is characterized by frequent attacks that occur during the day and also at night.

3. Management of Asthma

Despite asthma being incurable, health care professionals have outlined some strategies that can greatly assist in the management of asthma. Treatment, as stated by Parker-Oliver (2005), is usually regulated in accordance with the severity in which it presents. Even though it is argued that treatment strategies and goals should be negotiated with the patient, it is important to note that all objectives should be projected towards minimizing the impact of asthmatic symptoms as well as reducing dependence on reliever medicines (EMIS 2012). Asthma management should project towards reduction of the inflammatory states associated with this condition through environmental regulatory strategies in conjunction with the early utilization of disease modifying agents instead of focusing on symptomatic treatment alone (Crockett 2003). A personalized treatment plan should be created and modified regularly in order to meet the health needs of a person (Smith & Suero 2009). The most effective management strategies for asthma include identification of potential trigger factors and staying away from them (Gershwin & Klingelhofer 2001). In case avoidance of trigger factors does not yield positive results, it is always advisable for people presenting with asthma to seek specialized care (Buckley, 2000).

Medical treatments are dependent on the severity of asthmatic attacks as well as the frequency of these attacks (DIANE Publishing Company 1996).

3.1 Diagnosis of asthma

Diagnosis of asthma is carried out on the basis of medical history of a person and his or her family, physical examination and test results.

3.1.2 Workup/laboratory results

Physical exams are also used in diagnosis of asthma. During these tests the treating health practitioner listens to the breathing of a person in addition to looking for possible signs of asthma and allergy. Extreme difficulties in breathing, wheezing and swollen nasal passages are some of the signs that prove presence of asthma.

3.1.3 Differential diagnosis

Before starting major treatment for this disease healthcare practitioners carry out a variety of tests to determine that it is actually asthma. A variety of conditions that present with symptoms similar to those of asthma are misdiagnosed as asthma. Even though some conditions may be allergic and present with symptoms such as wheezing and difficulties in breathing they may asthma in actual sense (Levy Weller & Hilton 2006).

3.1.1 Signs and symptoms

Irritation and infection of the airways are some of the main factors that trigger asthmatic attacks. These attacks may occur all of a sudden or may develop slowly over a period of time. People suffering from asthma present with quite a number of symptoms some of which include: Wheezing, tightness of the chest, coughing, breathlessness and difficulty in speaking (Szefler & Leung 2001). Wheezing has been recognized as the most common asthmatic symptom. It is important to note that effective treatment of asthma should focus on potential causes rather than on symptoms (Rees, Kanabar & Pattani 2010).

3.2 Pre-hospital management

3.2.1 Primary and secondary survey

Pre-hospital management of asthma is beneficial since it helps ensure tat the patient is maintained in a stable condition before being given specialized care. Pre-hospital management involves assessment of the patient’s respiratory quality and effort in addition to his or her rate of blood oxygenation. Inhaled beta-agonists are widely used as first choice medications in prehospital management. Patients should never be released by emergency personnel before being transported to a medical facility for specialized treatment (Delbridge, Domeier & Key 2003).

3.3 Medical Management

3.3.1 Lifestyle modification

Besides drugs, modification of one’s lifestyle has also been recognized as an effective way in the management of asthma. Asthmatic patients re advised to keep away from second hand smoke in addition to strenuous activities that act to trigger asthmatic symptoms.

3.3. 2 Fast and long Medications therapy

Bronchodilators are the commonly used types of medication in the management of asthma. It is however important to note that these medications only provide short term relief and are not meant to provide total cure for asthma. Other medications used in conjunction with bronchodilators for those presenting with frequent asthmatic attacks include low dose inhaled glucocorticoids, mast cell stabilizers and luekotriene antagonists (Clark 2011). Glucocorticoids are inhaled to reduce cases of inflammation in the airways. Even though glucocorticoids do not result in complete cure for this disease, they repress the chronic inflammation of airways through inhibiting cytokines formation (National Health Call Centre Network Limited 2012).

3.3.3 Complementary medicine

Complementary medicine has also been made use of by some people in the management of asthma. Approximately 50% of those presenting with asthma utilize some form of unconventional therapy to manage this disease even though there is little evidence regarding the effectiveness of these therapies (Gershwin & Klingelhofer 2001). Research with respect to complementary treatment modalities such as respiratory therapeutic tactics, chiropractic strategies and psychotherapeutic modalities in addition to osteopathic therapies have not found sufficient facts to support their use in the management of asthma (Barnes et al 2008).

3.4 Prevention of Asthma

Reduction of exposure to trigger factors such as cigarette smoke and poisonous gases have been recognized as some of the most effective ways of minimizing cases of asthma attack (Parker-Oliver 2005). Environmental interventions have been recognized as some of the ways through which asthmatic attacks can be reduced. Exposure to a wide range of environmental factors has been shown to not only trigger asthmatic symptoms, but to also intensify the condition (Cicutto 2006). Carrying out tests to determine the types of aeroallergens in a particular area is an important strategy in the management of asthma (NHS 2012). These tests help in reducing exposure to allergens an aspect that has been shown to significantly reduce the need for drugs in addition to improving asthma control. People suffering from asthma should be totally discouraged from smoking (NHS 2012).

3.4.1 Swimming

Swimming has been recognized as one of the most beneficial exercises for persons suffering from asthma. While swimming people breathe in air just above the surface of the water, which is usually warmer and humid as compared to air elsewhere. Swimming is believed to increase lung volume in addition to helping develop excellent breathing techniques (Clark 2011).

3.4.2 Patient education

The principle objective of asthma management, according to Balter (2009), is achievement of a near normal life free totally from symptoms for those presenting with this disease. The other objective of asthma management is prevention of possible development of permanent lung damage as well as abnormal functioning of the lungs (DIANE Publishing Company 1996). Asthma education is essential since it equips patients with the capacity to successfully manage their condition between doctor visits (Balter 2009).

3.4.3 Future management prospects

Progress in management of asthma will require extensive research on the natural history of severe cases of this disease, pharmacogenetics, and pathogenesis and to a larger extent continuing development of novel drugs to meet the needs that are currently unmet (Rees, Kanabar & Pattani 2010).

4. Conclusion

4.1 Summary

Even though there is no cure for asthma, quite a number of treatment strategies have been identified that can assist in effective control of this disease. Despite there being no evidence as far as the most effective asthma prevention strategies are concerned, reduction of exposure to trigger factors such as cigarette smoke and poisonous gases have been recognized as some of the most effective ways of minimizing asthma attacks. Good management of asthma has high potential of significantly improving the lives of patients. The risk of developing this disease is higher among children who are exposed to trigger factors such as cigarette smoke and also among adults who are overweight.

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