Pathophysiology Of Emphysema

This essay will describe the pathophysiology of emphysema and the effect it had on a specific patient that I have chosen for this assignment. It will accomplish this by referring to the patients presenting symptoms and diagnosis and then by examining the changes that occur in the airways of an individual suffering from this chronic disease. The essay will continue by exploring the aims of treatment and how they may control the symptoms relating to the specific patient chosen. It will consider the relevant guidelines to treatment options in order to demonstrate evidence based practice.

Emphysema is chest condition that falls under the umbrella term of chronic obstructive pulmonary disease (COPD). This term also includes chronic bronchitis and asthma. Shahab, Jarvis, Britton and West (2006) suggest that COPD is a major contributor to global mortality and morbidity and its worldwide prevalence is likely to increase further. They continue by suggesting that it is well established that smoking is the single most important cause of COPD, increasing the risk of developing and dying from this condition by a factor of thirteen. COPD is characterised by airflow obstruction and is usually progressive, not fully reversible, and does not change markedly over several months. Sharafkaneh, Hanania and Kim (2008) suggest that an imbalance between protease and antiprotease activity in the lung is proposed as the major mechanism resulting in emphysema. Patients with emphysema complain of breathlessness, particularly on exertion, cough, chest tightness and often a reduction in their quality of life. This essay will explore the changes that occur in the lungs of a patient with emphysema and how these changes transpire.

The National Institute for Health and Clinical Excellence (NICE 2010) state that an estimated three million people in the UK have COPD. They also suggest that out of this figure only nine hundred thousand of these cases are confirmed, the remainder are people that have not yet presented with symptoms to their doctor. Exacerbation of COPD requiring hospital admission places a great burden on NHS resources. Davies (2009) suggests that costs directly related to caring for patients with COPD are over £500 million annually.

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Background of patient.http://faculty.washington.edu/alexbert/MEDEX/Spring/Spirometry.jpghttp://www.ispub.com/ispub/ijtm/volume_1_number_1_66/strongyloides_induced_respiratory_failure_6/strongy1a.jpg

To maintain patient confidentiality and for the purpose of this essay, the patient will be referred to as Janet. Janet is a 57 year old married woman. She has a history of smoking since the age of 15 and this equates to 42 pack years. She has worked in an office for her whole working life and enjoys walking. She attended the surgery as she was finding walking her dogs increasingly more difficult and was experiencing breathlessness on exertion. Janet’s weight was stable and she had not experienced any haemoptysis. Her baseline blood pressure and pulse where within normal limits and her body mass index (BMI) was in a healthy range. A full blood count (FBC) identified that Janet was not anaemic nor did she have polycythaemia which represents an abnormally high red blood cell count with a haematocrit greater than fifty percent. Janet’s peripheral oxygen saturation using a pulse oximeter was shown to be ninety four percent on air.

Chest x-ray showing hyperinflation – mdguy available at medpreponline.com

Pulmonary Function Tests – Medex Objectives 2003On examining Janet’s computerised records it was noted that she did not expectorate much sputum and she had only been prescribed one course of antibiotics for a chest infection in the past three years. Janet had been sent for a chest x-ray on her second visit to the surgery which had revealed hyperinflation of the lungs. Janet was subsequently referred for lung function tests at the local hospital where an obstructive pattern was identified. Spirometry is the test performed to demonstrate airflow obstruction however NICE (2010) state that airflow obstruction alone cannot be used as a diagnosis of COPD; it should only be used in conjunction with the patient demonstrating symptoms such as breathlessness or cough. A comprehensive history taking is very important as this can often identify COPD unaided. Janet was symptomatic and therefore was diagnosed with moderate COPD. Her spirometry showed she had a forced expiratory volume in the first second (FEV1) of 55% of her predicted value and a FEV1/forced vital capacity (FVC) ratio of less than 0.7. Predicted values for patients are predicted according to their height, gender, age and ethnic origin. The severity of airflow obstruction is graded according to the FEV1 reading. The updated NICE 2010 guidelines for COPD have reviewed the severity scales which mean that Janet’s spirometry readings fall into the moderate category. Janet’s degree of breathlessness was discussed and she graded herself as a level 3 on the Medical Research Council (MRC) dyspnoea score (Fletcher 1960). Emphysema often results in the patient having an increased residual lung volume which in due to air trapping; an inability to expel all the air from the lungs.

Aetiology and pathophysiology

Human lungs are the functional structure of the respiratory system. To understand Janet’s condition it is useful to look at how the normal respiratory system works. Its function is to supply the body with oxygen and to remove carbon dioxide (Marieb, 2004). Breathing is the movement of gases between the atmosphere and the lungs. For this to occur, there needs to be a system of open airways and pressure changes resulting from the action of the respiratory muscles in changing the volume of the chest cage. The diaphragm is the principal muscle of inspiration, assisted by the external intercostal muscles. The sternocleidomastoid and scalene muscles elevate the ribs and act as accessory muscles for inspiration. Expiration is aided by the elastic recoil of the respiratory muscles that were stretched during inspiration. Pulmonary gas exchange is conventionally divided into three processes: (1) ventilation or the flow of gases into and out of the alveoli of the lungs, (2) perfusion or flow of blood in the adjacent pulmonary capillaries, and (3) diffusion or transfer of gases between the alveoli and the pulmonary capillaries (Porth 2010). In addition to their gaseous exchange function, the lungs deactivate vasoactive substances such as bradykinin, convert Angiotensin 1 to Angiotensin 2 and serve as a reservoir for blood storage.

COPD is characterised by an intense inflammatory process in the airways, parenchyma and pulmonary vasculature (Sinden and Stockley 2010). The lung inflammatory response is characterised by increased number of neutrophils, macrophages and T lymphocytes. The accumulation of inflammatory components contributes to the lung injury in these patients. The mobilization of inflammatory cells to the lungs leads to the release of potentially destructive mediators including proteases and cytokines, which directly contribute to the remodelling and destruction of tissues. Truder, McGrath and Neptune (2003) believe that a delicate balance between protease and antiprotease activity is required for proper lung maintenance. Sharafkaneh, Hanania and Kim (2008) suggest that derangements of this balance results in destruction and inappropriate repair of lungs. They also suggest that macrophages are activated by tobacco smoke and recruit neutrophils and lymphocytes leading to elastolysis and emphysema. Similarly tobacco smoke activates airway epithelium to trigger airway remodelling. Both of these processes result in airflow obstruction.

http://www.scielo.br/img/revistas/mioc/v100s1/a27fig02.jpg

In addition to inflammation, oxidative stress caused by tobacco smoke inhalation plays a significant role in generating emphysema. Therefore Janet’s long history of smoking will have ultimately resulted in loss of elasticity to her lungs, retention of air in the lungs due to hyperinflation, expansion of the rib cage and flattening of the diaphragm. When the diaphragm is flattened, the muscles of the rib cage and abdomen take over the bulk of the work which is a less efficient and more tiring way of breathing.

The alveoli are the terminal air spaces of the respiratory tract and the sites of gaseous exchange between the air and the blood. Each alveolus is a cup-shaped sac with thin walls and each structure is separated by alveolar septa. A single network of capillaries occupies most of the septa, so blood is exposed to air on both sides. There are approximately three hundred million alveoli in the human lungs.

Emphysema jpg available at www.moondragon.orgEmphysema is characterized by a loss of lung elasticity and enlargement of the distal air spaces to the terminal bronchioles, with destruction of the alveolar walls and capillary beds. Several adjacent alveoli may rupture forming one large air sac that has a reduced ability to exchange oxygen and carbon dioxide. There is progressive destruction of the alveoli and the surrounding lung tissues as air is trapped in the damaged alveoli. This causes them to stretch which leads to hyperinflation and a reduced inability to exhale.http://www.moondragon.org/images/emphysema.jpg

Smoking tobacco is a well established cause of COPD (Shahab et al 2006). The Department of Health (2010) indicate that tobacco is the leading cause of preventable death and of health inequalities. They also state that in 2008, more than 80,000 premature deaths in England were caused by smoking. Callum (2008) suggests that the current level of tobacco use is estimated to cost the NHS around £2.7 billion every year. Cigarette smoke contains a range of toxic products and these have to be dealt with by the body. When cigarette smoke is inhaled into the lungs the cilia that normally sweep irritants out of the airways become paralyzed. The irritants therefore remain in the lungs infiltrating the alveoli where the damage process begins. Other causes of emphysema can be an inherited condition called alpha1 antitrypsin deficiency, an antiprotease enzyme that protects the lungs from injury. This accounts for approximately one percent of all cases of COPD. Occupation risks such as coal mining can also be a cause of COPD as the irritants inhaled act as the instigators of the disease process.

Interventions and treatments

Smoking cessation advice would be the most important intervention for Janet. Smoking cessation has been shown to be the most significant intervention to slow the rate of decline of lung function (Fletcher and Peto 1977). http://www.biomedcentral.com/content/figures/1471-2458-7-332-2-l.jpg The use of the Fletcher and Peto graph that demonstrates decline in lung function and the benefit of stopping smoking could be utilised in the process of addressing Janet’s smoking habit. The use of a smoking addiction calculator such as the Fagerstrom (1978) test was used to determine the extent Janet was addicted to nicotine. Parkes, Greenhalgh, Griffin and Dent (2008) found that informing a patient of their lung age appears to encourage higher levels of successful smoking cessation and Janet was surprised by her lung age of seventy seven. The damage to Janet’s lungs could not be repaired however the rate of disease progression could be reduced by her stopping smoking. Janet was referred to a specialist stopping smoking service in order to achieve a higher success rate. Encouraging patients with COPD to stop smoking is one of the most important components of their management. All COPD patients still smoking, regardless of age, should be encouraged to stop, and offered help to do so, at every opportunity (NICE 2010). Gruffydd-Jones (2006) recommends that all patients with any chronic lung condition should have an annual influenza vaccination and a “one-off” pneumococcal vaccination unless contraindicated. This is beneficial in reducing the risk of severe lung infections precipitating potentially fatal exacerbations of COPD.

Bronchodilators such as Salbutamol are frequently used as first line treatment for COPD. Treatment objectives include relieving symptoms such as dyspnoea and cough, slowing the accelerated decline in lung function, decreasing exacerbations, and improving quality of life. The NICE (2010) guideline for COPD recommends beginning treatment with bronchodilators. NICE are the guidelines used predominantly in primary care and will be used as guidance for treatment options in this assignment.

In theory, bronchodilators, which act directly on the airways, should have limited benefit in emphysema. However, Diaz, Bruns, Ezzie, Marchetti and Thomashow (2008) claim that in clinical practice many patients with emphysema, benefit from bronchodilator therapy. Pellegrino, Antonelli and Mondino (2010) agree that it is clinically justified to use short acting bronchodilators (SABA) in patients with emphysema.

The pharmacology of beta-2 receptorsSalbutamol is a beta-2 agonist. These bind to the beta-2 receptors on the smooth muscle of the trachea to the level of the terminal bronchioles. Binding of the beta-2 agonists to the beta-2 receptors activates a receptor associated G protein that in turn activates adenyl cyclase. This then converts adenosine triphosphate (ATP) to cyclic 3’5′-adenosine monophosphate (c-AMP), which then activates protein kinase A. The activated protein A prevents phosphorylation of the myosin light chain as well as activation of the Na+/Ca2+ exchange pump. This results in a fall in intracellular calcium and leads to smooth muscle relaxation, as less calcium is available for the calcium-dependent myosin-actin interaction required for smooth muscle contraction (Barnes 1995). Black, Oliver and Roth (2009) suggest that short acting beta-2 agonists can mediate further physiological responses to include the stimulation of beta-2 receptors on mast cells, leading to the suppression of inflammatory mediator release and the inhibition of extracellular matrix (ECM) protein release from airway fibroblasts.http://www.uky.edu/~mtp/adrenergic_pics/Beta2Effect.jpg

Janet was commenced on Salbutamol one hundred micrograms, two puffs as required and was reviewed after a four week period where it was identified that Janet remained breathless particularly on exertion and therefore her symptoms had not been improved upon. Following the NICE (2010) guidelines for COPD it was agreed with Janet to add in a long acting bronchodilator (LABA). She was commenced on Salmeterol twenty five micrograms two puffs twice a day. Diaz, Bruns, Ezzie, Marchetti and Thomashow (2008) claim that long acting bronchodilators such as Salmeterol have an affinity for the beta-2 receptor that is approximately one hundred times higher than that of short acting bronchodilators such as Salbutamol. The duration of action of Salmeterol is around twelve hours and hence only needs to be taken twice daily often helping with concordance. The benefits of LABAs are to improve respiratory symptoms, airflow, quality of life, rate of exacerbations and exercise tolerance. Patients with emphysema typically have a greater degree of hyperinflation than others with COPD and bronchodilators have been shown to improve hyperinflation at rest and during exercise.

As Janet rated herself as level three on the MRC dyspnoea scale, NICE (2010) recommend that the patient be referred for pulmonary rehabilitation. Pulmonary rehabilitation is defined as a multidisciplinary programme of care for patients with chronic respiratory impairment that is individually tailored and designed to optimise each patient’s physical and social performance and autonomy (NICE 2010). The rehabilitation process should incorporate a programme of physical training, disease education, and nutritional, psychological and behavioural intervention. The aims of pulmonary rehabilitation are to increase a person’s exercise tolerance and give support and advice which may include smoking cessation. It incorporates people with COPD who have undergone additional training to act as “buddies” to fellow sufferers. Many patients look upon pulmonary rehabilitation as a social occasion and this aspect helps to improve their quality of life.

Discussion.

This essay has examined the case of Janet who presented at primary care with dyspnoea on exertion. Janet has a history of smoking and following a chest x-ray and lung function tests, she was diagnosed with having COPD. Due to the nature of her symptoms and hyperinflation demonstrated on x-ray, it was concluded that Janet had emphysema which falls under the umbrella term of COPD along with chronic bronchitis and asthma. The rest of Janet’s history was unremarkable and her observations and blood tests were found to be normal.

COPD is characterised by airflow obstruction and is usually progressive, not fully reversible, and does not change markedly over several months. Patients with COPD often present in primary care with symptoms such as shortness of breath on exertion, cough or excessive sputum production. Usually the patient will already have damage to their lungs when they present with symptoms. The symptoms of COPD are extremely subjective and do not correspond to the FEV1 reading. For instance, two people could be seen with exactly the same reading of FEV1, but one patient would have very few symptoms and perhaps only need occasional use of a short acting bronchodilator whereas the other patient could be using two or more inhalers. Airway obstruction is diagnosed using spirometry and an FEV1 of <80% of predicted is classed as abnormal. The degree of severity in airway obstruction is calculated using the result of the FEV1. Janet’s FEV1 was 55% of her predicted value and using the NICE (2010) guidelines for COPD, this represents moderate airflow obstruction.

Smoking has been found to be the leading cause of COPD (DoH 2010). Therefore Janet’s long history of cigarette smoking has caused the damage in her lungs leading to inflammation and airway remodelling. Emphysema is characterised by the destruction of the alveolar walls and capillaries and loss of lung elasticity. This results in hyperinflation of the lungs caused by air trapping which for Janet means she has to use greater effort to exhale the air from her lungs. Often people with emphysema used “pursed lip” breathing which makes it easier for them to exhale. Hyperinflation of the lungs may lead to the chest shape changing to what is known as “barrel chest”. This represents an enlargement of the lungs and can be shown on x-ray.

The inflammatory response in this disease process is characterised by increased number of neutrophils, macrophages and T lymphocytes. The accumulation of inflammatory components contributes to the lung injury in these patients. The mobilization of inflammatory cells to the lungs leads to the release of potentially destructive mediators including proteases and cytokines, which directly contribute to the remodelling and destruction of tissues. The resulting damage to the alveoli affects the efficiency of the gaseous exchange which is reflected in Janet’s dyspnoea.

Smoking cessation is the most important intervention for Janet as although she cannot repair the damage already inflicted to her lungs, she can slow down any potential further damage. The use of specialist smoking cessation services has been shown to be beneficial to all patients with COPD and is recommended on the NICE (2010) guidelines. Janet was referred to her local group and has reduced her nicotine intake although she has not fully stopped as yet.

Bronchodilators have been shown to benefit patients with emphysema (Diaz, Bruns, Ezzie, Marchetti and Thomashow 2008). Janet was prescribed Salbutamol on an as needed basis however, despite using it at least four times a day, she remained short of breath. Janet agreed to the addition of a long acting bronchodilator Salmeterol twice daily and she found that this controlled her symptoms more effectively. Bronchodilators work by binding to the receptors that affect smooth muscle contraction; they work by initiating a chemical process that leads to smooth muscle relaxation.

Janet was referred for pulmonary rehabilitation. She attended this twice a week for six weeks and found it beneficial to her exercise tolerance but also her overall well being and quality of life. It has hopefully given her the knowledge into the condition of emphysema to allow her to improve her lifestyle and slow down the disease process.

The use of national guidelines has been found to be helpful in assisting treatment options for patients suffering from COPD.

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